diff options
48 files changed, 364 insertions, 1400 deletions
diff --git a/arch/alpha/include/asm/mutex.h b/arch/alpha/include/asm/mutex.h deleted file mode 100644 index 458c1f7fbc18..000000000000 --- a/arch/alpha/include/asm/mutex.h +++ /dev/null @@ -1,9 +0,0 @@ -/* - * Pull in the generic implementation for the mutex fastpath. - * - * TODO: implement optimized primitives instead, or leave the generic - * implementation in place, or pick the atomic_xchg() based generic - * implementation. (see asm-generic/mutex-xchg.h for details) - */ - -#include <asm-generic/mutex-dec.h> diff --git a/arch/arc/include/asm/mutex.h b/arch/arc/include/asm/mutex.h deleted file mode 100644 index a2f88ff9f506..000000000000 --- a/arch/arc/include/asm/mutex.h +++ /dev/null @@ -1,18 +0,0 @@ -/* - * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation. - */ - -/* - * xchg() based mutex fast path maintains a state of 0 or 1, as opposed to - * atomic dec based which can "count" any number of lock contenders. - * This ideally needs to be fixed in core, but for now switching to dec ver. - */ -#if defined(CONFIG_SMP) && (CONFIG_NR_CPUS > 2) -#include <asm-generic/mutex-dec.h> -#else -#include <asm-generic/mutex-xchg.h> -#endif diff --git a/arch/arm/include/asm/mutex.h b/arch/arm/include/asm/mutex.h deleted file mode 100644 index 87c044910fe0..000000000000 --- a/arch/arm/include/asm/mutex.h +++ /dev/null @@ -1,21 +0,0 @@ -/* - * arch/arm/include/asm/mutex.h - * - * ARM optimized mutex locking primitives - * - * Please look into asm-generic/mutex-xchg.h for a formal definition. - */ -#ifndef _ASM_MUTEX_H -#define _ASM_MUTEX_H -/* - * On pre-ARMv6 hardware this results in a swp-based implementation, - * which is the most efficient. For ARMv6+, we have exclusive memory - * accessors and use atomic_dec to avoid the extra xchg operations - * on the locking slowpaths. - */ -#if __LINUX_ARM_ARCH__ < 6 -#include <asm-generic/mutex-xchg.h> -#else -#include <asm-generic/mutex-dec.h> -#endif -#endif /* _ASM_MUTEX_H */ diff --git a/arch/arm64/include/asm/Kbuild b/arch/arm64/include/asm/Kbuild index 44e1d7f10add..b4ab238a59ec 100644 --- a/arch/arm64/include/asm/Kbuild +++ b/arch/arm64/include/asm/Kbuild @@ -24,7 +24,6 @@ generic-y += mm-arch-hooks.h generic-y += mman.h generic-y += msgbuf.h generic-y += msi.h -generic-y += mutex.h generic-y += poll.h generic-y += preempt.h generic-y += resource.h diff --git a/arch/avr32/include/asm/mutex.h b/arch/avr32/include/asm/mutex.h deleted file mode 100644 index 458c1f7fbc18..000000000000 --- a/arch/avr32/include/asm/mutex.h +++ /dev/null @@ -1,9 +0,0 @@ -/* - * Pull in the generic implementation for the mutex fastpath. - * - * TODO: implement optimized primitives instead, or leave the generic - * implementation in place, or pick the atomic_xchg() based generic - * implementation. (see asm-generic/mutex-xchg.h for details) - */ - -#include <asm-generic/mutex-dec.h> diff --git a/arch/blackfin/include/asm/Kbuild b/arch/blackfin/include/asm/Kbuild index 91d49c0a3118..2fb67b59d188 100644 --- a/arch/blackfin/include/asm/Kbuild +++ b/arch/blackfin/include/asm/Kbuild @@ -24,7 +24,6 @@ generic-y += mcs_spinlock.h generic-y += mm-arch-hooks.h generic-y += mman.h generic-y += msgbuf.h -generic-y += mutex.h generic-y += param.h generic-y += percpu.h generic-y += pgalloc.h diff --git a/arch/c6x/include/asm/mutex.h b/arch/c6x/include/asm/mutex.h deleted file mode 100644 index 7a7248e0462d..000000000000 --- a/arch/c6x/include/asm/mutex.h +++ /dev/null @@ -1,6 +0,0 @@ -#ifndef _ASM_C6X_MUTEX_H -#define _ASM_C6X_MUTEX_H - -#include <asm-generic/mutex-null.h> - -#endif /* _ASM_C6X_MUTEX_H */ diff --git a/arch/cris/include/asm/mutex.h b/arch/cris/include/asm/mutex.h deleted file mode 100644 index 458c1f7fbc18..000000000000 --- a/arch/cris/include/asm/mutex.h +++ /dev/null @@ -1,9 +0,0 @@ -/* - * Pull in the generic implementation for the mutex fastpath. - * - * TODO: implement optimized primitives instead, or leave the generic - * implementation in place, or pick the atomic_xchg() based generic - * implementation. (see asm-generic/mutex-xchg.h for details) - */ - -#include <asm-generic/mutex-dec.h> diff --git a/arch/frv/include/asm/mutex.h b/arch/frv/include/asm/mutex.h deleted file mode 100644 index 458c1f7fbc18..000000000000 --- a/arch/frv/include/asm/mutex.h +++ /dev/null @@ -1,9 +0,0 @@ -/* - * Pull in the generic implementation for the mutex fastpath. - * - * TODO: implement optimized primitives instead, or leave the generic - * implementation in place, or pick the atomic_xchg() based generic - * implementation. (see asm-generic/mutex-xchg.h for details) - */ - -#include <asm-generic/mutex-dec.h> diff --git a/arch/h8300/include/asm/mutex.h b/arch/h8300/include/asm/mutex.h deleted file mode 100644 index 458c1f7fbc18..000000000000 --- a/arch/h8300/include/asm/mutex.h +++ /dev/null @@ -1,9 +0,0 @@ -/* - * Pull in the generic implementation for the mutex fastpath. - * - * TODO: implement optimized primitives instead, or leave the generic - * implementation in place, or pick the atomic_xchg() based generic - * implementation. (see asm-generic/mutex-xchg.h for details) - */ - -#include <asm-generic/mutex-dec.h> diff --git a/arch/hexagon/include/asm/mutex.h b/arch/hexagon/include/asm/mutex.h deleted file mode 100644 index 58b52de1bc22..000000000000 --- a/arch/hexagon/include/asm/mutex.h +++ /dev/null @@ -1,8 +0,0 @@ -/* - * Pull in the generic implementation for the mutex fastpath. - * - * TODO: implement optimized primitives instead, or leave the generic - * implementation in place, or pick the atomic_xchg() based generic - * implementation. (see asm-generic/mutex-xchg.h for details) - */ -#include <asm-generic/mutex-xchg.h> diff --git a/arch/ia64/include/asm/mutex.h b/arch/ia64/include/asm/mutex.h deleted file mode 100644 index 28cb819e0ff9..000000000000 --- a/arch/ia64/include/asm/mutex.h +++ /dev/null @@ -1,90 +0,0 @@ -/* - * ia64 implementation of the mutex fastpath. - * - * Copyright (C) 2006 Ken Chen <kenneth.w.chen@intel.com> - * - */ - -#ifndef _ASM_MUTEX_H -#define _ASM_MUTEX_H - -/** - * __mutex_fastpath_lock - try to take the lock by moving the count - * from 1 to a 0 value - * @count: pointer of type atomic_t - * @fail_fn: function to call if the original value was not 1 - * - * Change the count from 1 to a value lower than 1, and call <fail_fn> if - * it wasn't 1 originally. This function MUST leave the value lower than - * 1 even when the "1" assertion wasn't true. - */ -static inline void -__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *)) -{ - if (unlikely(ia64_fetchadd4_acq(count, -1) != 1)) - fail_fn(count); -} - -/** - * __mutex_fastpath_lock_retval - try to take the lock by moving the count - * from 1 to a 0 value - * @count: pointer of type atomic_t - * - * Change the count from 1 to a value lower than 1. This function returns 0 - * if the fastpath succeeds, or -1 otherwise. - */ -static inline int -__mutex_fastpath_lock_retval(atomic_t *count) -{ - if (unlikely(ia64_fetchadd4_acq(count, -1) != 1)) - return -1; - return 0; -} - -/** - * __mutex_fastpath_unlock - try to promote the count from 0 to 1 - * @count: pointer of type atomic_t - * @fail_fn: function to call if the original value was not 0 - * - * Try to promote the count from 0 to 1. If it wasn't 0, call <fail_fn>. - * In the failure case, this function is allowed to either set the value to - * 1, or to set it to a value lower than 1. - * - * If the implementation sets it to a value of lower than 1, then the - * __mutex_slowpath_needs_to_unlock() macro needs to return 1, it needs - * to return 0 otherwise. - */ -static inline void -__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *)) -{ - int ret = ia64_fetchadd4_rel(count, 1); - if (unlikely(ret < 0)) - fail_fn(count); -} - -#define __mutex_slowpath_needs_to_unlock() 1 - -/** - * __mutex_fastpath_trylock - try to acquire the mutex, without waiting - * - * @count: pointer of type atomic_t - * @fail_fn: fallback function - * - * Change the count from 1 to a value lower than 1, and return 0 (failure) - * if it wasn't 1 originally, or return 1 (success) otherwise. This function - * MUST leave the value lower than 1 even when the "1" assertion wasn't true. - * Additionally, if the value was < 0 originally, this function must not leave - * it to 0 on failure. - * - * If the architecture has no effective trylock variant, it should call the - * <fail_fn> spinlock-based trylock variant unconditionally. - */ -static inline int -__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *)) -{ - if (atomic_read(count) == 1 && cmpxchg_acq(count, 1, 0) == 1) - return 1; - return 0; -} - -#endif diff --git a/arch/m32r/include/asm/mutex.h b/arch/m32r/include/asm/mutex.h deleted file mode 100644 index 458c1f7fbc18..000000000000 --- a/arch/m32r/include/asm/mutex.h +++ /dev/null @@ -1,9 +0,0 @@ -/* - * Pull in the generic implementation for the mutex fastpath. - * - * TODO: implement optimized primitives instead, or leave the generic - * implementation in place, or pick the atomic_xchg() based generic - * implementation. (see asm-generic/mutex-xchg.h for details) - */ - -#include <asm-generic/mutex-dec.h> diff --git a/arch/m68k/include/asm/Kbuild b/arch/m68k/include/asm/Kbuild index eb85bd9c6180..1f2e5d31cb24 100644 --- a/arch/m68k/include/asm/Kbuild +++ b/arch/m68k/include/asm/Kbuild @@ -20,7 +20,6 @@ generic-y += local64.h generic-y += mcs_spinlock.h generic-y += mm-arch-hooks.h generic-y += mman.h -generic-y += mutex.h generic-y += percpu.h generic-y += preempt.h generic-y += resource.h diff --git a/arch/metag/include/asm/Kbuild b/arch/metag/include/asm/Kbuild index 29acb89daaaa..167150c701d1 100644 --- a/arch/metag/include/asm/Kbuild +++ b/arch/metag/include/asm/Kbuild @@ -27,7 +27,6 @@ generic-y += local64.h generic-y += mcs_spinlock.h generic-y += mm-arch-hooks.h generic-y += msgbuf.h -generic-y += mutex.h generic-y += param.h generic-y += pci.h generic-y += percpu.h diff --git a/arch/microblaze/include/asm/mutex.h b/arch/microblaze/include/asm/mutex.h deleted file mode 100644 index ff6101aa2c71..000000000000 --- a/arch/microblaze/include/asm/mutex.h +++ /dev/null @@ -1 +0,0 @@ -#include <asm-generic/mutex-dec.h> diff --git a/arch/mips/include/asm/Kbuild b/arch/mips/include/asm/Kbuild index 9740066cc631..3269b742a75e 100644 --- a/arch/mips/include/asm/Kbuild +++ b/arch/mips/include/asm/Kbuild @@ -9,7 +9,6 @@ generic-y += irq_work.h generic-y += local64.h generic-y += mcs_spinlock.h generic-y += mm-arch-hooks.h -generic-y += mutex.h generic-y += parport.h generic-y += percpu.h generic-y += preempt.h diff --git a/arch/mn10300/include/asm/mutex.h b/arch/mn10300/include/asm/mutex.h deleted file mode 100644 index 84f5490c6fb4..000000000000 --- a/arch/mn10300/include/asm/mutex.h +++ /dev/null @@ -1,16 +0,0 @@ -/* MN10300 Mutex fastpath - * - * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. - * Written by David Howells (dhowells@redhat.com) - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public Licence - * as published by the Free Software Foundation; either version - * 2 of the Licence, or (at your option) any later version. - * - * - * TODO: implement optimized primitives instead, or leave the generic - * implementation in place, or pick the atomic_xchg() based generic - * implementation. (see asm-generic/mutex-xchg.h for details) - */ -#include <asm-generic/mutex-null.h> diff --git a/arch/nios2/include/asm/mutex.h b/arch/nios2/include/asm/mutex.h deleted file mode 100644 index ff6101aa2c71..000000000000 --- a/arch/nios2/include/asm/mutex.h +++ /dev/null @@ -1 +0,0 @@ -#include <asm-generic/mutex-dec.h> diff --git a/arch/openrisc/include/asm/mutex.h b/arch/openrisc/include/asm/mutex.h deleted file mode 100644 index b85a0cfa9fc9..000000000000 --- a/arch/openrisc/include/asm/mutex.h +++ /dev/null @@ -1,27 +0,0 @@ -/* - * OpenRISC Linux - * - * Linux architectural port borrowing liberally from similar works of - * others. All original copyrights apply as per the original source - * declaration. - * - * OpenRISC implementation: - * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> - * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> - * et al. - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - */ - -/* - * Pull in the generic implementation for the mutex fastpath. - * - * TODO: implement optimized primitives instead, or leave the generic - * implementation in place, or pick the atomic_xchg() based generic - * implementation. (see asm-generic/mutex-xchg.h for details) - */ - -#include <asm-generic/mutex-dec.h> diff --git a/arch/parisc/include/asm/Kbuild b/arch/parisc/include/asm/Kbuild index f9b3a81aefcd..91f53c07f410 100644 --- a/arch/parisc/include/asm/Kbuild +++ b/arch/parisc/include/asm/Kbuild @@ -16,7 +16,6 @@ generic-y += local.h generic-y += local64.h generic-y += mcs_spinlock.h generic-y += mm-arch-hooks.h -generic-y += mutex.h generic-y += param.h generic-y += percpu.h generic-y += poll.h diff --git a/arch/powerpc/include/asm/mutex.h b/arch/powerpc/include/asm/mutex.h deleted file mode 100644 index 078155fa1189..000000000000 --- a/arch/powerpc/include/asm/mutex.h +++ /dev/null @@ -1,132 +0,0 @@ -/* - * Optimised mutex implementation of include/asm-generic/mutex-dec.h algorithm - */ -#ifndef _ASM_POWERPC_MUTEX_H -#define _ASM_POWERPC_MUTEX_H - -static inline int __mutex_cmpxchg_lock(atomic_t *v, int old, int new) -{ - int t; - - __asm__ __volatile__ ( -"1: lwarx %0,0,%1 # mutex trylock\n\ - cmpw 0,%0,%2\n\ - bne- 2f\n" - PPC405_ERR77(0,%1) -" stwcx. %3,0,%1\n\ - bne- 1b" - PPC_ACQUIRE_BARRIER - "\n\ -2:" - : "=&r" (t) - : "r" (&v->counter), "r" (old), "r" (new) - : "cc", "memory"); - - return t; -} - -static inline int __mutex_dec_return_lock(atomic_t *v) -{ - int t; - - __asm__ __volatile__( -"1: lwarx %0,0,%1 # mutex lock\n\ - addic %0,%0,-1\n" - PPC405_ERR77(0,%1) -" stwcx. %0,0,%1\n\ - bne- 1b" - PPC_ACQUIRE_BARRIER - : "=&r" (t) - : "r" (&v->counter) - : "cc", "memory"); - - return t; -} - -static inline int __mutex_inc_return_unlock(atomic_t *v) -{ - int t; - - __asm__ __volatile__( - PPC_RELEASE_BARRIER -"1: lwarx %0,0,%1 # mutex unlock\n\ - addic %0,%0,1\n" - PPC405_ERR77(0,%1) -" stwcx. %0,0,%1 \n\ - bne- 1b" - : "=&r" (t) - : "r" (&v->counter) - : "cc", "memory"); - - return t; -} - -/** - * __mutex_fastpath_lock - try to take the lock by moving the count - * from 1 to a 0 value - * @count: pointer of type atomic_t - * @fail_fn: function to call if the original value was not 1 - * - * Change the count from 1 to a value lower than 1, and call <fail_fn> if - * it wasn't 1 originally. This function MUST leave the value lower than - * 1 even when the "1" assertion wasn't true. - */ -static inline void -__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *)) -{ - if (unlikely(__mutex_dec_return_lock(count) < 0)) - fail_fn(count); -} - -/** - * __mutex_fastpath_lock_retval - try to take the lock by moving the count - * from 1 to a 0 value - * @count: pointer of type atomic_t - * - * Change the count from 1 to a value lower than 1. This function returns 0 - * if the fastpath succeeds, or -1 otherwise. - */ -static inline int -__mutex_fastpath_lock_retval(atomic_t *count) -{ - if (unlikely(__mutex_dec_return_lock(count) < 0)) - return -1; - return 0; -} - -/** - * __mutex_fastpath_unlock - try to promote the count from 0 to 1 - * @count: pointer of type atomic_t - * @fail_fn: function to call if the original value was not 0 - * - * Try to promote the count from 0 to 1. If it wasn't 0, call <fail_fn>. - * In the failure case, this function is allowed to either set the value to - * 1, or to set it to a value lower than 1. - */ -static inline void -__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *)) -{ - if (unlikely(__mutex_inc_return_unlock(count) <= 0)) - fail_fn(count); -} - -#define __mutex_slowpath_needs_to_unlock() 1 - -/** - * __mutex_fastpath_trylock - try to acquire the mutex, without waiting - * - * @count: pointer of type atomic_t - * @fail_fn: fallback function - * - * Change the count from 1 to 0, and return 1 (success), or if the count - * was not 1, then return 0 (failure). - */ -static inline int -__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *)) -{ - if (likely(atomic_read(count) == 1 && __mutex_cmpxchg_lock(count, 1, 0) == 1)) - return 1; - return 0; -} - -#endif diff --git a/arch/s390/include/asm/mutex.h b/arch/s390/include/asm/mutex.h deleted file mode 100644 index 458c1f7fbc18..000000000000 --- a/arch/s390/include/asm/mutex.h +++ /dev/null @@ -1,9 +0,0 @@ -/* - * Pull in the generic implementation for the mutex fastpath. - * - * TODO: implement optimized primitives instead, or leave the generic - * implementation in place, or pick the atomic_xchg() based generic - * implementation. (see asm-generic/mutex-xchg.h for details) - */ - -#include <asm-generic/mutex-dec.h> diff --git a/arch/score/include/asm/mutex.h b/arch/score/include/asm/mutex.h deleted file mode 100644 index 10d48fe4db97..000000000000 --- a/arch/score/include/asm/mutex.h +++ /dev/null @@ -1,6 +0,0 @@ -#ifndef _ASM_SCORE_MUTEX_H -#define _ASM_SCORE_MUTEX_H - -#include <asm-generic/mutex-dec.h> - -#endif /* _ASM_SCORE_MUTEX_H */ diff --git a/arch/sh/include/asm/mutex-llsc.h b/arch/sh/include/asm/mutex-llsc.h deleted file mode 100644 index dad29b687bd3..000000000000 --- a/arch/sh/include/asm/mutex-llsc.h +++ /dev/null @@ -1,109 +0,0 @@ -/* - * arch/sh/include/asm/mutex-llsc.h - * - * SH-4A optimized mutex locking primitives - * - * Please look into asm-generic/mutex-xchg.h for a formal definition. - */ -#ifndef __ASM_SH_MUTEX_LLSC_H -#define __ASM_SH_MUTEX_LLSC_H - -/* - * Attempting to lock a mutex on SH4A is done like in ARMv6+ architecure. - * with a bastardized atomic decrement (it is not a reliable atomic decrement - * but it satisfies the defined semantics for our purpose, while being - * smaller and faster than a real atomic decrement or atomic swap. - * The idea is to attempt decrementing the lock value only once. If once - * decremented it isn't zero, or if its store-back fails due to a dispute - * on the exclusive store, we simply bail out immediately through the slow - * path where the lock will be reattempted until it succeeds. - */ -static inline void -__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *)) -{ - int __done, __res; - - __asm__ __volatile__ ( - "movli.l @%2, %0 \n" - "add #-1, %0 \n" - "movco.l %0, @%2 \n" - "movt %1 \n" - : "=&z" (__res), "=&r" (__done) - : "r" (&(count)->counter) - : "t"); - - if (unlikely(!__done || __res != 0)) - fail_fn(count); -} - -static inline int -__mutex_fastpath_lock_retval(atomic_t *count) -{ - int __done, __res; - - __asm__ __volatile__ ( - "movli.l @%2, %0 \n" - "add #-1, %0 \n" - "movco.l %0, @%2 \n" - "movt %1 \n" - : "=&z" (__res), "=&r" (__done) - : "r" (&(count)->counter) - : "t"); - - if (unlikely(!__done || __res != 0)) - __res = -1; - - return __res; -} - -static inline void -__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *)) -{ - int __done, __res; - - __asm__ __volatile__ ( - "movli.l @%2, %0 \n\t" - "add #1, %0 \n\t" - "movco.l %0, @%2 \n\t" - "movt %1 \n\t" - : "=&z" (__res), "=&r" (__done) - : "r" (&(count)->counter) - : "t"); - - if (unlikely(!__done || __res <= 0)) - fail_fn(count); -} - -/* - * If the unlock was done on a contended lock, or if the unlock simply fails - * then the mutex remains locked. - */ -#define __mutex_slowpath_needs_to_unlock() 1 - -/* - * For __mutex_fastpath_trylock we do an atomic decrement and check the - * result and put it in the __res variable. - */ -static inline int -__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *)) -{ - int __res, __orig; - - __asm__ __volatile__ ( - "1: movli.l @%2, %0 \n\t" - "dt %0 \n\t" - "movco.l %0,@%2 \n\t" - "bf 1b \n\t" - "cmp/eq #0,%0 \n\t" - "bt 2f \n\t" - "mov #0, %1 \n\t" - "bf 3f \n\t" - "2: mov #1, %1 \n\t" - "3: " - : "=&z" (__orig), "=&r" (__res) - : "r" (&count->counter) - : "t"); - - return __res; -} -#endif /* __ASM_SH_MUTEX_LLSC_H */ diff --git a/arch/sh/include/asm/mutex.h b/arch/sh/include/asm/mutex.h deleted file mode 100644 index d8e37716a4a0..000000000000 --- a/arch/sh/include/asm/mutex.h +++ /dev/null @@ -1,12 +0,0 @@ -/* - * Pull in the generic implementation for the mutex fastpath. - * - * TODO: implement optimized primitives instead, or leave the generic - * implementation in place, or pick the atomic_xchg() based generic - * implementation. (see asm-generic/mutex-xchg.h for details) - */ -#if defined(CONFIG_CPU_SH4A) -#include <asm/mutex-llsc.h> -#else -#include <asm-generic/mutex-dec.h> -#endif diff --git a/arch/sparc/include/asm/Kbuild b/arch/sparc/include/asm/Kbuild index cfc918067f80..0569bfac4afb 100644 --- a/arch/sparc/include/asm/Kbuild +++ b/arch/sparc/include/asm/Kbuild @@ -15,7 +15,6 @@ generic-y += local64.h generic-y += mcs_spinlock.h generic-y += mm-arch-hooks.h generic-y += module.h -generic-y += mutex.h generic-y += preempt.h generic-y += rwsem.h generic-y += serial.h diff --git a/arch/tile/include/asm/Kbuild b/arch/tile/include/asm/Kbuild index ba35c41c71ff..2d1f5638974c 100644 --- a/arch/tile/include/asm/Kbuild +++ b/arch/tile/include/asm/Kbuild @@ -21,7 +21,6 @@ generic-y += local64.h generic-y += mcs_spinlock.h generic-y += mm-arch-hooks.h generic-y += msgbuf.h -generic-y += mutex.h generic-y += param.h generic-y += parport.h generic-y += poll.h diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild index 904f3ebf4220..052f7f6d0551 100644 --- a/arch/um/include/asm/Kbuild +++ b/arch/um/include/asm/Kbuild @@ -17,7 +17,6 @@ generic-y += irq_work.h generic-y += kdebug.h generic-y += mcs_spinlock.h generic-y += mm-arch-hooks.h -generic-y += mutex.h generic-y += param.h generic-y += pci.h generic-y += percpu.h diff --git a/arch/unicore32/include/asm/mutex.h b/arch/unicore32/include/asm/mutex.h deleted file mode 100644 index fab7d0e8adf6..000000000000 --- a/arch/unicore32/include/asm/mutex.h +++ /dev/null @@ -1,20 +0,0 @@ -/* - * linux/arch/unicore32/include/asm/mutex.h - * - * Code specific to PKUnity SoC and UniCore ISA - * - * Copyright (C) 2001-2010 GUAN Xue-tao - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation. - * - * UniCore optimized mutex locking primitives - * - * Please look into asm-generic/mutex-xchg.h for a formal definition. - */ -#ifndef __UNICORE_MUTEX_H__ -#define __UNICORE_MUTEX_H__ - -# include <asm-generic/mutex-xchg.h> -#endif diff --git a/arch/x86/include/asm/mutex.h b/arch/x86/include/asm/mutex.h deleted file mode 100644 index 7d3a48275394..000000000000 --- a/arch/x86/include/asm/mutex.h +++ /dev/null @@ -1,5 +0,0 @@ -#ifdef CONFIG_X86_32 -# include <asm/mutex_32.h> -#else -# include <asm/mutex_64.h> -#endif diff --git a/arch/x86/include/asm/mutex_32.h b/arch/x86/include/asm/mutex_32.h deleted file mode 100644 index e9355a84fc67..000000000000 --- a/arch/x86/include/asm/mutex_32.h +++ /dev/null @@ -1,110 +0,0 @@ -/* - * Assembly implementation of the mutex fastpath, based on atomic - * decrement/increment. - * - * started by Ingo Molnar: - * - * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> - */ -#ifndef _ASM_X86_MUTEX_32_H -#define _ASM_X86_MUTEX_32_H - -#include <asm/alternative.h> - -/** - * __mutex_fastpath_lock - try to take the lock by moving the count - * from 1 to a 0 value - * @count: pointer of type atomic_t - * @fn: function to call if the original value was not 1 - * - * Change the count from 1 to a value lower than 1, and call <fn> if it - * wasn't 1 originally. This function MUST leave the value lower than 1 - * even when the "1" assertion wasn't true. - */ -#define __mutex_fastpath_lock(count, fail_fn) \ -do { \ - unsigned int dummy; \ - \ - typecheck(atomic_t *, count); \ - typecheck_fn(void (*)(atomic_t *), fail_fn); \ - \ - asm volatile(LOCK_PREFIX " decl (%%eax)\n" \ - " jns 1f \n" \ - " call " #fail_fn "\n" \ - "1:\n" \ - : "=a" (dummy) \ - : "a" (count) \ - : "memory", "ecx", "edx"); \ -} while (0) - - -/** - * __mutex_fastpath_lock_retval - try to take the lock by moving the count - * from 1 to a 0 value - * @count: pointer of type atomic_t - * - * Change the count from 1 to a value lower than 1. This function returns 0 - * if the fastpath succeeds, or -1 otherwise. - */ -static inline int __mutex_fastpath_lock_retval(atomic_t *count) -{ - if (unlikely(atomic_dec_return(count) < 0)) - return -1; - else - return 0; -} - -/** - * __mutex_fastpath_unlock - try to promote the mutex from 0 to 1 - * @count: pointer of type atomic_t - * @fail_fn: function to call if the original value was not 0 - * - * try to promote the mutex from 0 to 1. if it wasn't 0, call <fail_fn>. - * In the failure case, this function is allowed to either set the value - * to 1, or to set it to a value lower than 1. - * - * If the implementation sets it to a value of lower than 1, the - * __mutex_slowpath_needs_to_unlock() macro needs to return 1, it needs - * to return 0 otherwise. - */ -#define __mutex_fastpath_unlock(count, fail_fn) \ -do { \ - unsigned int dummy; \ - \ - typecheck(atomic_t *, count); \ - typecheck_fn(void (*)(atomic_t *), fail_fn); \ - \ - asm volatile(LOCK_PREFIX " incl (%%eax)\n" \ - " jg 1f\n" \ - " call " #fail_fn "\n" \ - "1:\n" \ - : "=a" (dummy) \ - : "a" (count) \ - : "memory", "ecx", "edx"); \ -} while (0) - -#define __mutex_slowpath_needs_to_unlock() 1 - -/** - * __mutex_fastpath_trylock - try to acquire the mutex, without waiting - * - * @count: pointer of type atomic_t - * @fail_fn: fallback function - * - * Change the count from 1 to a value lower than 1, and return 0 (failure) - * if it wasn't 1 originally, or return 1 (success) otherwise. This function - * MUST leave the value lower than 1 even when the "1" assertion wasn't true. - * Additionally, if the value was < 0 originally, this function must not leave - * it to 0 on failure. - */ -static inline int __mutex_fastpath_trylock(atomic_t *count, - int (*fail_fn)(atomic_t *)) -{ - /* cmpxchg because it never induces a false contention state. */ - if (likely(atomic_read(count) == 1 && atomic_cmpxchg(count, 1, 0) == 1)) - return 1; - - return 0; -} - -#endif /* _ASM_X86_MUTEX_32_H */ diff --git a/arch/x86/include/asm/mutex_64.h b/arch/x86/include/asm/mutex_64.h deleted file mode 100644 index d9850758464e..000000000000 --- a/arch/x86/include/asm/mutex_64.h +++ /dev/null @@ -1,127 +0,0 @@ -/* - * Assembly implementation of the mutex fastpath, based on atomic - * decrement/increment. - * - * started by Ingo Molnar: - * - * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> - */ -#ifndef _ASM_X86_MUTEX_64_H -#define _ASM_X86_MUTEX_64_H - -/** - * __mutex_fastpath_lock - decrement and call function if negative - * @v: pointer of type atomic_t - * @fail_fn: function to call if the result is negative - * - * Atomically decrements @v and calls <fail_fn> if the result is negative. - */ -#ifdef CC_HAVE_ASM_GOTO -static inline void __mutex_fastpath_lock(atomic_t *v, - void (*fail_fn)(atomic_t *)) -{ - asm_volatile_goto(LOCK_PREFIX " decl %0\n" - " jns %l[exit]\n" - : : "m" (v->counter) - : "memory", "cc" - : exit); - fail_fn(v); -exit: - return; -} -#else -#define __mutex_fastpath_lock(v, fail_fn) \ -do { \ - unsigned long dummy; \ - \ - typecheck(atomic_t *, v); \ - typecheck_fn(void (*)(atomic_t *), fail_fn); \ - \ - asm volatile(LOCK_PREFIX " decl (%%rdi)\n" \ - " jns 1f \n" \ - " call " #fail_fn "\n" \ - "1:" \ - : "=D" (dummy) \ - : "D" (v) \ - : "rax", "rsi", "rdx", "rcx", \ - "r8", "r9", "r10", "r11", "memory"); \ -} while (0) -#endif - -/** - * __mutex_fastpath_lock_retval - try to take the lock by moving the count - * from 1 to a 0 value - * @count: pointer of type atomic_t - * - * Change the count from 1 to a value lower than 1. This function returns 0 - * if the fastpath succeeds, or -1 otherwise. - */ -static inline int __mutex_fastpath_lock_retval(atomic_t *count) -{ - if (unlikely(atomic_dec_return(count) < 0)) - return -1; - else - return 0; -} - -/** - * __mutex_fastpath_unlock - increment and call function if nonpositive - * @v: pointer of type atomic_t - * @fail_fn: function to call if the result is nonpositive - * - * Atomically increments @v and calls <fail_fn> if the result is nonpositive. - */ -#ifdef CC_HAVE_ASM_GOTO -static inline void __mutex_fastpath_unlock(atomic_t *v, - void (*fail_fn)(atomic_t *)) -{ - asm_volatile_goto(LOCK_PREFIX " incl %0\n" - " jg %l[exit]\n" - : : "m" (v->counter) - : "memory", "cc" - : exit); - fail_fn(v); -exit: - return; -} -#else -#define __mutex_fastpath_unlock(v, fail_fn) \ -do { \ - unsigned long dummy; \ - \ - typecheck(atomic_t *, v); \ - typecheck_fn(void (*)(atomic_t *), fail_fn); \ - \ - asm volatile(LOCK_PREFIX " incl (%%rdi)\n" \ - " jg 1f\n" \ - " call " #fail_fn "\n" \ - "1:" \ - : "=D" (dummy) \ - : "D" (v) \ - : "rax", "rsi", "rdx", "rcx", \ - "r8", "r9", "r10", "r11", "memory"); \ -} while (0) -#endif - -#define __mutex_slowpath_needs_to_unlock() 1 - -/** - * __mutex_fastpath_trylock - try to acquire the mutex, without waiting - * - * @count: pointer of type atomic_t - * @fail_fn: fallback function - * - * Change the count from 1 to 0 and return 1 (success), or return 0 (failure) - * if it wasn't 1 originally. [the fallback function is never used on - * x86_64, because all x86_64 CPUs have a CMPXCHG instruction.] - */ -static inline int __mutex_fastpath_trylock(atomic_t *count, - int (*fail_fn)(atomic_t *)) -{ - if (likely(atomic_read(count) == 1 && atomic_cmpxchg(count, 1, 0) == 1)) - return 1; - - return 0; -} - -#endif /* _ASM_X86_MUTEX_64_H */ diff --git a/arch/xtensa/include/asm/mutex.h b/arch/xtensa/include/asm/mutex.h deleted file mode 100644 index 458c1f7fbc18..000000000000 --- a/arch/xtensa/include/asm/mutex.h +++ /dev/null @@ -1,9 +0,0 @@ -/* - * Pull in the generic implementation for the mutex fastpath. - * - * TODO: implement optimized primitives instead, or leave the generic - * implementation in place, or pick the atomic_xchg() based generic - * implementation. (see asm-generic/mutex-xchg.h for details) - */ - -#include <asm-generic/mutex-dec.h> diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c index 1c237d02f30b..e9bd2a81d03a 100644 --- a/drivers/gpu/drm/i915/i915_gem_shrinker.c +++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c @@ -35,19 +35,6 @@ #include "i915_drv.h" #include "i915_trace.h" -static bool mutex_is_locked_by(struct mutex *mutex, struct task_struct *task) -{ - if (!mutex_is_locked(mutex)) - return false; - -#if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_MUTEX_SPIN_ON_OWNER) - return mutex->owner == task; -#else - /* Since UP may be pre-empted, we cannot assume that we own the lock */ - return false; -#endif -} - static bool any_vma_pinned(struct drm_i915_gem_object *obj) { struct i915_vma *vma; @@ -240,14 +227,10 @@ unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv) static bool i915_gem_shrinker_lock(struct drm_device *dev, bool *unlock) { - if (!mutex_trylock(&dev->struct_mutex)) { - if (!mutex_is_locked_by(&dev->struct_mutex, current)) - return false; - - *unlock = false; - } else - *unlock = true; + if (!mutex_trylock(&dev->struct_mutex)) + return false; + *unlock = true; return true; } diff --git a/drivers/gpu/drm/msm/msm_gem_shrinker.c b/drivers/gpu/drm/msm/msm_gem_shrinker.c index 283d2841ba58..6d2e885bd58e 100644 --- a/drivers/gpu/drm/msm/msm_gem_shrinker.c +++ b/drivers/gpu/drm/msm/msm_gem_shrinker.c @@ -18,29 +18,12 @@ #include "msm_drv.h" #include "msm_gem.h" -static bool mutex_is_locked_by(struct mutex *mutex, struct task_struct *task) -{ - if (!mutex_is_locked(mutex)) - return false; - -#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_MUTEXES) - return mutex->owner == task; -#else - /* Since UP may be pre-empted, we cannot assume that we own the lock */ - return false; -#endif -} - static bool msm_gem_shrinker_lock(struct drm_device *dev, bool *unlock) { - if (!mutex_trylock(&dev->struct_mutex)) { - if (!mutex_is_locked_by(&dev->struct_mutex, current)) - return false; - *unlock = false; - } else { - *unlock = true; - } + if (!mutex_trylock(&dev->struct_mutex)) + return false; + *unlock = true; return true; } diff --git a/include/asm-generic/mutex-dec.h b/include/asm-generic/mutex-dec.h deleted file mode 100644 index c54829d3de37..000000000000 --- a/include/asm-generic/mutex-dec.h +++ /dev/null @@ -1,88 +0,0 @@ -/* - * include/asm-generic/mutex-dec.h - * - * Generic implementation of the mutex fastpath, based on atomic - * decrement/increment. - */ -#ifndef _ASM_GENERIC_MUTEX_DEC_H -#define _ASM_GENERIC_MUTEX_DEC_H - -/** - * __mutex_fastpath_lock - try to take the lock by moving the count - * from 1 to a 0 value - * @count: pointer of type atomic_t - * @fail_fn: function to call if the original value was not 1 - * - * Change the count from 1 to a value lower than 1, and call <fail_fn> if - * it wasn't 1 originally. This function MUST leave the value lower than - * 1 even when the "1" assertion wasn't true. - */ -static inline void -__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *)) -{ - if (unlikely(atomic_dec_return_acquire(count) < 0)) - fail_fn(count); -} - -/** - * __mutex_fastpath_lock_retval - try to take the lock by moving the count - * from 1 to a 0 value - * @count: pointer of type atomic_t - * - * Change the count from 1 to a value lower than 1. This function returns 0 - * if the fastpath succeeds, or -1 otherwise. - */ -static inline int -__mutex_fastpath_lock_retval(atomic_t *count) -{ - if (unlikely(atomic_dec_return_acquire(count) < 0)) - return -1; - return 0; -} - -/** - * __mutex_fastpath_unlock - try to promote the count from 0 to 1 - * @count: pointer of type atomic_t - * @fail_fn: function to call if the original value was not 0 - * - * Try to promote the count from 0 to 1. If it wasn't 0, call <fail_fn>. - * In the failure case, this function is allowed to either set the value to - * 1, or to set it to a value lower than 1. - * - * If the implementation sets it to a value of lower than 1, then the - * __mutex_slowpath_needs_to_unlock() macro needs to return 1, it needs - * to return 0 otherwise. - */ -static inline void -__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *)) -{ - if (unlikely(atomic_inc_return_release(count) <= 0)) - fail_fn(count); -} - -#define __mutex_slowpath_needs_to_unlock() 1 - -/** - * __mutex_fastpath_trylock - try to acquire the mutex, without waiting - * - * @count: pointer of type atomic_t - * @fail_fn: fallback function - * - * Change the count from 1 to a value lower than 1, and return 0 (failure) - * if it wasn't 1 originally, or return 1 (success) otherwise. This function - * MUST leave the value lower than 1 even when the "1" assertion wasn't true. - * Additionally, if the value was < 0 originally, this function must not leave - * it to 0 on failure. - * - * If the architecture has no effective trylock variant, it should call the - * <fail_fn> spinlock-based trylock variant unconditionally. - */ -static inline int -__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *)) -{ - if (likely(atomic_read(count) == 1 && atomic_cmpxchg_acquire(count, 1, 0) == 1)) - return 1; - return 0; -} - -#endif diff --git a/include/asm-generic/mutex-null.h b/include/asm-generic/mutex-null.h deleted file mode 100644 index 61069ed334e2..000000000000 --- a/include/asm-generic/mutex-null.h +++ /dev/null @@ -1,19 +0,0 @@ -/* - * include/asm-generic/mutex-null.h - * - * Generic implementation of the mutex fastpath, based on NOP :-) - * - * This is used by the mutex-debugging infrastructure, but it can also - * be used by architectures that (for whatever reason) want to use the - * spinlock based slowpath. - */ -#ifndef _ASM_GENERIC_MUTEX_NULL_H -#define _ASM_GENERIC_MUTEX_NULL_H - -#define __mutex_fastpath_lock(count, fail_fn) fail_fn(count) -#define __mutex_fastpath_lock_retval(count) (-1) -#define __mutex_fastpath_unlock(count, fail_fn) fail_fn(count) -#define __mutex_fastpath_trylock(count, fail_fn) fail_fn(count) -#define __mutex_slowpath_needs_to_unlock() 1 - -#endif diff --git a/include/asm-generic/mutex-xchg.h b/include/asm-generic/mutex-xchg.h deleted file mode 100644 index 3269ec4e195f..000000000000 --- a/include/asm-generic/mutex-xchg.h +++ /dev/null @@ -1,120 +0,0 @@ -/* - * include/asm-generic/mutex-xchg.h - * - * Generic implementation of the mutex fastpath, based on xchg(). - * - * NOTE: An xchg based implementation might be less optimal than an atomic - * decrement/increment based implementation. If your architecture - * has a reasonable atomic dec/inc then you should probably use - * asm-generic/mutex-dec.h instead, or you could open-code an - * optimized version in asm/mutex.h. - */ -#ifndef _ASM_GENERIC_MUTEX_XCHG_H -#define _ASM_GENERIC_MUTEX_XCHG_H - -/** - * __mutex_fastpath_lock - try to take the lock by moving the count - * from 1 to a 0 value - * @count: pointer of type atomic_t - * @fail_fn: function to call if the original value was not 1 - * - * Change the count from 1 to a value lower than 1, and call <fail_fn> if it - * wasn't 1 originally. This function MUST leave the value lower than 1 - * even when the "1" assertion wasn't true. - */ -static inline void -__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *)) -{ - if (unlikely(atomic_xchg(count, 0) != 1)) - /* - * We failed to acquire the lock, so mark it contended - * to ensure that any waiting tasks are woken up by the - * unlock slow path. - */ - if (likely(atomic_xchg_acquire(count, -1) != 1)) - fail_fn(count); -} - -/** - * __mutex_fastpath_lock_retval - try to take the lock by moving the count - * from 1 to a 0 value - * @count: pointer of type atomic_t - * - * Change the count from 1 to a value lower than 1. This function returns 0 - * if the fastpath succeeds, or -1 otherwise. - */ -static inline int -__mutex_fastpath_lock_retval(atomic_t *count) -{ - if (unlikely(atomic_xchg_acquire(count, 0) != 1)) - if (likely(atomic_xchg(count, -1) != 1)) - return -1; - return 0; -} - -/** - * __mutex_fastpath_unlock - try to promote the mutex from 0 to 1 - * @count: pointer of type atomic_t - * @fail_fn: function to call if the original value was not 0 - * - * try to promote the mutex from 0 to 1. if it wasn't 0, call <function> - * In the failure case, this function is allowed to either set the value to - * 1, or to set it to a value lower than one. - * If the implementation sets it to a value of lower than one, the - * __mutex_slowpath_needs_to_unlock() macro needs to return 1, it needs - * to return 0 otherwise. - */ -static inline void -__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *)) -{ - if (unlikely(atomic_xchg_release(count, 1) != 0)) - fail_fn(count); -} - -#define __mutex_slowpath_needs_to_unlock() 0 - -/** - * __mutex_fastpath_trylock - try to acquire the mutex, without waiting - * - * @count: pointer of type atomic_t - * @fail_fn: spinlock based trylock implementation - * - * Change the count from 1 to a value lower than 1, and return 0 (failure) - * if it wasn't 1 originally, or return 1 (success) otherwise. This function - * MUST leave the value lower than 1 even when the "1" assertion wasn't true. - * Additionally, if the value was < 0 originally, this function must not leave - * it to 0 on failure. - * - * If the architecture has no effective trylock variant, it should call the - * <fail_fn> spinlock-based trylock variant unconditionally. - */ -static inline int -__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *)) -{ - int prev; - - if (atomic_read(count) != 1) - return 0; - - prev = atomic_xchg_acquire(count, 0); - if (unlikely(prev < 0)) { - /* - * The lock was marked contended so we must restore that - * state. If while doing so we get back a prev value of 1 - * then we just own it. - * - * [ In the rare case of the mutex going to 1, to 0, to -1 - * and then back to 0 in this few-instructions window, - * this has the potential to trigger the slowpath for the - * owner's unlock path needlessly, but that's not a problem - * in practice. ] - */ - prev = atomic_xchg_acquire(count, prev); - if (prev < 0) - prev = 0; - } - - return prev; -} - -#endif diff --git a/include/asm-generic/mutex.h b/include/asm-generic/mutex.h deleted file mode 100644 index fe91ab502793..000000000000 --- a/include/asm-generic/mutex.h +++ /dev/null @@ -1,9 +0,0 @@ -#ifndef __ASM_GENERIC_MUTEX_H -#define __ASM_GENERIC_MUTEX_H -/* - * Pull in the generic implementation for the mutex fastpath, - * which is a reasonable default on many architectures. - */ - -#include <asm-generic/mutex-dec.h> -#endif /* __ASM_GENERIC_MUTEX_H */ diff --git a/include/linux/mutex-debug.h b/include/linux/mutex-debug.h deleted file mode 100644 index 4ac8b1977b73..000000000000 --- a/include/linux/mutex-debug.h +++ /dev/null @@ -1,24 +0,0 @@ -#ifndef __LINUX_MUTEX_DEBUG_H -#define __LINUX_MUTEX_DEBUG_H - -#include <linux/linkage.h> -#include <linux/lockdep.h> -#include <linux/debug_locks.h> - -/* - * Mutexes - debugging helpers: - */ - -#define __DEBUG_MUTEX_INITIALIZER(lockname) \ - , .magic = &lockname - -#define mutex_init(mutex) \ -do { \ - static struct lock_class_key __key; \ - \ - __mutex_init((mutex), #mutex, &__key); \ -} while (0) - -extern void mutex_destroy(struct mutex *lock); - -#endif diff --git a/include/linux/mutex.h b/include/linux/mutex.h index 2cb7531e7d7a..4d3bccabbea5 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -18,6 +18,7 @@ #include <linux/atomic.h> #include <asm/processor.h> #include <linux/osq_lock.h> +#include <linux/debug_locks.h> /* * Simple, straightforward mutexes with strict semantics: @@ -48,16 +49,12 @@ * locks and tasks (and only those tasks) */ struct mutex { - /* 1: unlocked, 0: locked, negative: locked, possible waiters */ - atomic_t count; + atomic_long_t owner; spinlock_t wait_lock; - struct list_head wait_list; -#if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_MUTEX_SPIN_ON_OWNER) - struct task_struct *owner; -#endif #ifdef CONFIG_MUTEX_SPIN_ON_OWNER struct optimistic_spin_queue osq; /* Spinner MCS lock */ #endif + struct list_head wait_list; #ifdef CONFIG_DEBUG_MUTEXES void *magic; #endif @@ -66,6 +63,11 @@ struct mutex { #endif }; +static inline struct task_struct *__mutex_owner(struct mutex *lock) +{ + return (struct task_struct *)(atomic_long_read(&lock->owner) & ~0x03); +} + /* * This is the control structure for tasks blocked on mutex, * which resides on the blocked task's kernel stack: @@ -79,9 +81,20 @@ struct mutex_waiter { }; #ifdef CONFIG_DEBUG_MUTEXES -# include <linux/mutex-debug.h> + +#define __DEBUG_MUTEX_INITIALIZER(lockname) \ + , .magic = &lockname + +extern void mutex_destroy(struct mutex *lock); + #else + # define __DEBUG_MUTEX_INITIALIZER(lockname) + +static inline void mutex_destroy(struct mutex *lock) {} + +#endif + /** * mutex_init - initialize the mutex * @mutex: the mutex to be initialized @@ -90,14 +103,12 @@ struct mutex_waiter { * * It is not allowed to initialize an already locked mutex. */ -# define mutex_init(mutex) \ -do { \ - static struct lock_class_key __key; \ - \ - __mutex_init((mutex), #mutex, &__key); \ +#define mutex_init(mutex) \ +do { \ + static struct lock_class_key __key; \ + \ + __mutex_init((mutex), #mutex, &__key); \ } while (0) -static inline void mutex_destroy(struct mutex *lock) {} -#endif #ifdef CONFIG_DEBUG_LOCK_ALLOC # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \ @@ -107,7 +118,7 @@ static inline void mutex_destroy(struct mutex *lock) {} #endif #define __MUTEX_INITIALIZER(lockname) \ - { .count = ATOMIC_INIT(1) \ + { .owner = ATOMIC_LONG_INIT(0) \ , .wait_lock = __SPIN_LOCK_UNLOCKED(lockname.wait_lock) \ , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \ __DEBUG_MUTEX_INITIALIZER(lockname) \ @@ -127,7 +138,10 @@ extern void __mutex_init(struct mutex *lock, const char *name, */ static inline int mutex_is_locked(struct mutex *lock) { - return atomic_read(&lock->count) != 1; + /* + * XXX think about spin_is_locked + */ + return __mutex_owner(lock) != NULL; } /* diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks index ebdb0043203a..84d882f3e299 100644 --- a/kernel/Kconfig.locks +++ b/kernel/Kconfig.locks @@ -225,7 +225,7 @@ config ARCH_SUPPORTS_ATOMIC_RMW config MUTEX_SPIN_ON_OWNER def_bool y - depends on SMP && !DEBUG_MUTEXES && ARCH_SUPPORTS_ATOMIC_RMW + depends on SMP && ARCH_SUPPORTS_ATOMIC_RMW config RWSEM_SPIN_ON_OWNER def_bool y diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c index 9c951fade415..9aa713629387 100644 --- a/kernel/locking/mutex-debug.c +++ b/kernel/locking/mutex-debug.c @@ -73,21 +73,8 @@ void debug_mutex_unlock(struct mutex *lock) { if (likely(debug_locks)) { DEBUG_LOCKS_WARN_ON(lock->magic != lock); - - if (!lock->owner) - DEBUG_LOCKS_WARN_ON(!lock->owner); - else - DEBUG_LOCKS_WARN_ON(lock->owner != current); - DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next); } - - /* - * __mutex_slowpath_needs_to_unlock() is explicitly 0 for debug - * mutexes so that we can do it here after we've verified state. - */ - mutex_clear_owner(lock); - atomic_set(&lock->count, 1); } void debug_mutex_init(struct mutex *lock, const char *name, diff --git a/kernel/locking/mutex-debug.h b/kernel/locking/mutex-debug.h index 57a871ae3c81..a459faa48987 100644 --- a/kernel/locking/mutex-debug.h +++ b/kernel/locking/mutex-debug.h @@ -27,16 +27,6 @@ extern void debug_mutex_unlock(struct mutex *lock); extern void debug_mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key); -static inline void mutex_set_owner(struct mutex *lock) -{ - WRITE_ONCE(lock->owner, current); -} - -static inline void mutex_clear_owner(struct mutex *lock) -{ - WRITE_ONCE(lock->owner, NULL); -} - #define spin_lock_mutex(lock, flags) \ do { \ struct mutex *l = container_of(lock, struct mutex, wait_lock); \ diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index a70b90db3909..17a88e929e6a 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -27,41 +27,176 @@ #include <linux/debug_locks.h> #include <linux/osq_lock.h> -/* - * In the DEBUG case we are using the "NULL fastpath" for mutexes, - * which forces all calls into the slowpath: - */ #ifdef CONFIG_DEBUG_MUTEXES # include "mutex-debug.h" -# include <asm-generic/mutex-null.h> -/* - * Must be 0 for the debug case so we do not do the unlock outside of the - * wait_lock region. debug_mutex_unlock() will do the actual unlock in this - * case. - */ -# undef __mutex_slowpath_needs_to_unlock -# define __mutex_slowpath_needs_to_unlock() 0 #else # include "mutex.h" -# include <asm/mutex.h> #endif void __mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key) { - atomic_set(&lock->count, 1); + atomic_long_set(&lock->owner, 0); spin_lock_init(&lock->wait_lock); INIT_LIST_HEAD(&lock->wait_list); - mutex_clear_owner(lock); #ifdef CONFIG_MUTEX_SPIN_ON_OWNER osq_lock_init(&lock->osq); #endif debug_mutex_init(lock, name, key); } - EXPORT_SYMBOL(__mutex_init); +/* + * @owner: contains: 'struct task_struct *' to the current lock owner, + * NULL means not owned. Since task_struct pointers are aligned at + * ARCH_MIN_TASKALIGN (which is at least sizeof(void *)), we have low + * bits to store extra state. + * + * Bit0 indicates a non-empty waiter list; unlock must issue a wakeup. + * Bit1 indicates unlock needs to hand the lock to the top-waiter + */ +#define MUTEX_FLAG_WAITERS 0x01 +#define MUTEX_FLAG_HANDOFF 0x02 + +#define MUTEX_FLAGS 0x03 + +static inline struct task_struct *__owner_task(unsigned long owner) +{ + return (struct task_struct *)(owner & ~MUTEX_FLAGS); +} + +static inline unsigned long __owner_flags(unsigned long owner) +{ + return owner & MUTEX_FLAGS; +} + +/* + * Actual trylock that will work on any unlocked state. + * + * When setting the owner field, we must preserve the low flag bits. + * + * Be careful with @handoff, only set that in a wait-loop (where you set + * HANDOFF) to avoid recursive lock attempts. + */ +static inline bool __mutex_trylock(struct mutex *lock, const bool handoff) +{ + unsigned long owner, curr = (unsigned long)current; + + owner = atomic_long_read(&lock->owner); + for (;;) { /* must loop, can race against a flag */ + unsigned long old, flags = __owner_flags(owner); + + if (__owner_task(owner)) { + if (handoff && unlikely(__owner_task(owner) == current)) { + /* + * Provide ACQUIRE semantics for the lock-handoff. + * + * We cannot easily use load-acquire here, since + * the actual load is a failed cmpxchg, which + * doesn't imply any barriers. + * + * Also, this is a fairly unlikely scenario, and + * this contains the cost. + */ + smp_mb(); /* ACQUIRE */ + return true; + } + + return false; + } + + /* + * We set the HANDOFF bit, we must make sure it doesn't live + * past the point where we acquire it. This would be possible + * if we (accidentally) set the bit on an unlocked mutex. + */ + if (handoff) + flags &= ~MUTEX_FLAG_HANDOFF; + + old = atomic_long_cmpxchg_acquire(&lock->owner, owner, curr | flags); + if (old == owner) + return true; + + owner = old; + } +} + +#ifndef CONFIG_DEBUG_LOCK_ALLOC +/* + * Lockdep annotations are contained to the slow paths for simplicity. + * There is nothing that would stop spreading the lockdep annotations outwards + * except more code. + */ + +/* + * Optimistic trylock that only works in the uncontended case. Make sure to + * follow with a __mutex_trylock() before failing. + */ +static __always_inline bool __mutex_trylock_fast(struct mutex *lock) +{ + unsigned long curr = (unsigned long)current; + + if (!atomic_long_cmpxchg_acquire(&lock->owner, 0UL, curr)) + return true; + + return false; +} + +static __always_inline bool __mutex_unlock_fast(struct mutex *lock) +{ + unsigned long curr = (unsigned long)current; + + if (atomic_long_cmpxchg_release(&lock->owner, curr, 0UL) == curr) + return true; + + return false; +} +#endif + +static inline void __mutex_set_flag(struct mutex *lock, unsigned long flag) +{ + atomic_long_or(flag, &lock->owner); +} + +static inline void __mutex_clear_flag(struct mutex *lock, unsigned long flag) +{ + atomic_long_andnot(flag, &lock->owner); +} + +static inline bool __mutex_waiter_is_first(struct mutex *lock, struct mutex_waiter *waiter) +{ + return list_first_entry(&lock->wait_list, struct mutex_waiter, list) == waiter; +} + +/* + * Give up ownership to a specific task, when @task = NULL, this is equivalent + * to a regular unlock. Clears HANDOFF, preserves WAITERS. Provides RELEASE + * semantics like a regular unlock, the __mutex_trylock() provides matching + * ACQUIRE semantics for the handoff. + */ +static void __mutex_handoff(struct mutex *lock, struct task_struct *task) +{ + unsigned long owner = atomic_long_read(&lock->owner); + + for (;;) { + unsigned long old, new; + +#ifdef CONFIG_DEBUG_MUTEXES + DEBUG_LOCKS_WARN_ON(__owner_task(owner) != current); +#endif + + new = (owner & MUTEX_FLAG_WAITERS); + new |= (unsigned long)task; + + old = atomic_long_cmpxchg_release(&lock->owner, owner, new); + if (old == owner) + break; + + owner = old; + } +} + #ifndef CONFIG_DEBUG_LOCK_ALLOC /* * We split the mutex lock/unlock logic into separate fastpath and @@ -69,7 +204,7 @@ EXPORT_SYMBOL(__mutex_init); * We also put the fastpath first in the kernel image, to make sure the * branch is predicted by the CPU as default-untaken. */ -__visible void __sched __mutex_lock_slowpath(atomic_t *lock_count); +static void __sched __mutex_lock_slowpath(struct mutex *lock); /** * mutex_lock - acquire the mutex @@ -95,14 +230,10 @@ __visible void __sched __mutex_lock_slowpath(atomic_t *lock_count); void __sched mutex_lock(struct mutex *lock) { might_sleep(); - /* - * The locking fastpath is the 1->0 transition from - * 'unlocked' into 'locked' state. - */ - __mutex_fastpath_lock(&lock->count, __mutex_lock_slowpath); - mutex_set_owner(lock); -} + if (!__mutex_trylock_fast(lock)) + __mutex_lock_slowpath(lock); +} EXPORT_SYMBOL(mutex_lock); #endif @@ -149,9 +280,6 @@ static __always_inline void ww_mutex_lock_acquired(struct ww_mutex *ww, /* * After acquiring lock with fastpath or when we lost out in contested * slowpath, set ctx and wake up any waiters so they can recheck. - * - * This function is never called when CONFIG_DEBUG_LOCK_ALLOC is set, - * as the fastpath and opportunistic spinning are disabled in that case. */ static __always_inline void ww_mutex_set_context_fastpath(struct ww_mutex *lock, @@ -176,7 +304,7 @@ ww_mutex_set_context_fastpath(struct ww_mutex *lock, /* * Check if lock is contended, if not there is nobody to wake up */ - if (likely(atomic_read(&lock->base.count) == 0)) + if (likely(!(atomic_long_read(&lock->base.owner) & MUTEX_FLAG_WAITERS))) return; /* @@ -227,7 +355,7 @@ bool mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner) bool ret = true; rcu_read_lock(); - while (lock->owner == owner) { + while (__mutex_owner(lock) == owner) { /* * Ensure we emit the owner->on_cpu, dereference _after_ * checking lock->owner still matches owner. If that fails, @@ -260,27 +388,20 @@ static inline int mutex_can_spin_on_owner(struct mutex *lock) return 0; rcu_read_lock(); - owner = READ_ONCE(lock->owner); + owner = __mutex_owner(lock); if (owner) retval = owner->on_cpu; rcu_read_unlock(); + /* - * if lock->owner is not set, the mutex owner may have just acquired - * it and not set the owner yet or the mutex has been released. + * If lock->owner is not set, the mutex has been released. Return true + * such that we'll trylock in the spin path, which is a faster option + * than the blocking slow path. */ return retval; } /* - * Atomically try to take the lock when it is available - */ -static inline bool mutex_try_to_acquire(struct mutex *lock) -{ - return !mutex_is_locked(lock) && - (atomic_cmpxchg_acquire(&lock->count, 1, 0) == 1); -} - -/* * Optimistic spinning. * * We try to spin for acquisition when we find that the lock owner @@ -288,13 +409,6 @@ static inline bool mutex_try_to_acquire(struct mutex *lock) * need to reschedule. The rationale is that if the lock owner is * running, it is likely to release the lock soon. * - * Since this needs the lock owner, and this mutex implementation - * doesn't track the owner atomically in the lock field, we need to - * track it non-atomically. - * - * We can't do this for DEBUG_MUTEXES because that relies on wait_lock - * to serialize everything. - * * The mutex spinners are queued up using MCS lock so that only one * spinner can compete for the mutex. However, if mutex spinning isn't * going to happen, there is no point in going through the lock/unlock @@ -302,24 +416,39 @@ static inline bool mutex_try_to_acquire(struct mutex *lock) * * Returns true when the lock was taken, otherwise false, indicating * that we need to jump to the slowpath and sleep. + * + * The waiter flag is set to true if the spinner is a waiter in the wait + * queue. The waiter-spinner will spin on the lock directly and concurrently + * with the spinner at the head of the OSQ, if present, until the owner is + * changed to itself. */ static bool mutex_optimistic_spin(struct mutex *lock, - struct ww_acquire_ctx *ww_ctx, const bool use_ww_ctx) + struct ww_acquire_ctx *ww_ctx, + const bool use_ww_ctx, const bool waiter) { struct task_struct *task = current; - if (!mutex_can_spin_on_owner(lock)) - goto done; + if (!waiter) { + /* + * The purpose of the mutex_can_spin_on_owner() function is + * to eliminate the overhead of osq_lock() and osq_unlock() + * in case spinning isn't possible. As a waiter-spinner + * is not going to take OSQ lock anyway, there is no need + * to call mutex_can_spin_on_owner(). + */ + if (!mutex_can_spin_on_owner(lock)) + goto fail; - /* - * In order to avoid a stampede of mutex spinners trying to - * acquire the mutex all at once, the spinners need to take a - * MCS (queued) lock first before spinning on the owner field. - */ - if (!osq_lock(&lock->osq)) - goto done; + /* + * In order to avoid a stampede of mutex spinners trying to + * acquire the mutex all at once, the spinners need to take a + * MCS (queued) lock first before spinning on the owner field. + */ + if (!osq_lock(&lock->osq)) + goto fail; + } - while (true) { + for (;;) { struct task_struct *owner; if (use_ww_ctx && ww_ctx->acquired > 0) { @@ -335,40 +464,26 @@ static bool mutex_optimistic_spin(struct mutex *lock, * performed the optimistic spinning cannot be done. */ if (READ_ONCE(ww->ctx)) - break; + goto fail_unlock; } /* * If there's an owner, wait for it to either * release the lock or go to sleep. */ - owner = READ_ONCE(lock->owner); - if (owner && !mutex_spin_on_owner(lock, owner)) - break; - - /* Try to acquire the mutex if it is unlocked. */ - if (mutex_try_to_acquire(lock)) { - lock_acquired(&lock->dep_map, ip); - - if (use_ww_ctx) { - struct ww_mutex *ww; - ww = container_of(lock, struct ww_mutex, base); - - ww_mutex_set_context_fastpath(ww, ww_ctx); + owner = __mutex_owner(lock); + if (owner) { + if (waiter && owner == task) { + smp_mb(); /* ACQUIRE */ + break; } - mutex_set_owner(lock); - osq_unlock(&lock->osq); - return true; + if (!mutex_spin_on_owner(lock, owner)) + goto fail_unlock; } - /* - * When there's no owner, we might have preempted between the - * owner acquiring the lock and setting the owner field. If - * we're an RT task that will live-lock because we won't let - * the owner complete. - */ - if (!owner && (need_resched() || rt_task(task))) + /* Try to acquire the mutex if it is unlocked. */ + if (__mutex_trylock(lock, waiter)) break; /* @@ -380,8 +495,17 @@ static bool mutex_optimistic_spin(struct mutex *lock, cpu_relax_lowlatency(); } - osq_unlock(&lock->osq); -done: + if (!waiter) + osq_unlock(&lock->osq); + + return true; + + +fail_unlock: + if (!waiter) + osq_unlock(&lock->osq); + +fail: /* * If we fell out of the spin path because of need_resched(), * reschedule now, before we try-lock the mutex. This avoids getting @@ -400,14 +524,14 @@ done: } #else static bool mutex_optimistic_spin(struct mutex *lock, - struct ww_acquire_ctx *ww_ctx, const bool use_ww_ctx) + struct ww_acquire_ctx *ww_ctx, + const bool use_ww_ctx, const bool waiter) { return false; } #endif -__visible __used noinline -void __sched __mutex_unlock_slowpath(atomic_t *lock_count); +static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigned long ip); /** * mutex_unlock - release the mutex @@ -422,21 +546,12 @@ void __sched __mutex_unlock_slowpath(atomic_t *lock_count); */ void __sched mutex_unlock(struct mutex *lock) { - /* - * The unlocking fastpath is the 0->1 transition from 'locked' - * into 'unlocked' state: - */ -#ifndef CONFIG_DEBUG_MUTEXES - /* - * When debugging is enabled we must not clear the owner before time, - * the slow path will always be taken, and that clears the owner field - * after verifying that it was indeed current. - */ - mutex_clear_owner(lock); +#ifndef CONFIG_DEBUG_LOCK_ALLOC + if (__mutex_unlock_fast(lock)) + return; #endif - __mutex_fastpath_unlock(&lock->count, __mutex_unlock_slowpath); + __mutex_unlock_slowpath(lock, _RET_IP_); } - EXPORT_SYMBOL(mutex_unlock); /** @@ -465,15 +580,7 @@ void __sched ww_mutex_unlock(struct ww_mutex *lock) lock->ctx = NULL; } -#ifndef CONFIG_DEBUG_MUTEXES - /* - * When debugging is enabled we must not clear the owner before time, - * the slow path will always be taken, and that clears the owner field - * after verifying that it was indeed current. - */ - mutex_clear_owner(&lock->base); -#endif - __mutex_fastpath_unlock(&lock->base.count, __mutex_unlock_slowpath); + mutex_unlock(&lock->base); } EXPORT_SYMBOL(ww_mutex_unlock); @@ -509,10 +616,12 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, struct task_struct *task = current; struct mutex_waiter waiter; unsigned long flags; + bool first = false; + struct ww_mutex *ww; int ret; if (use_ww_ctx) { - struct ww_mutex *ww = container_of(lock, struct ww_mutex, base); + ww = container_of(lock, struct ww_mutex, base); if (unlikely(ww_ctx == READ_ONCE(ww->ctx))) return -EALREADY; } @@ -520,20 +629,21 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, preempt_disable(); mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip); - if (mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx)) { + if (__mutex_trylock(lock, false) || + mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx, false)) { /* got the lock, yay! */ + lock_acquired(&lock->dep_map, ip); + if (use_ww_ctx) + ww_mutex_set_context_fastpath(ww, ww_ctx); preempt_enable(); return 0; } spin_lock_mutex(&lock->wait_lock, flags); - /* - * Once more, try to acquire the lock. Only try-lock the mutex if - * it is unlocked to reduce unnecessary xchg() operations. + * After waiting to acquire the wait_lock, try again. */ - if (!mutex_is_locked(lock) && - (atomic_xchg_acquire(&lock->count, 0) == 1)) + if (__mutex_trylock(lock, false)) goto skip_wait; debug_mutex_lock_common(lock, &waiter); @@ -543,26 +653,26 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, list_add_tail(&waiter.list, &lock->wait_list); waiter.task = task; + if (__mutex_waiter_is_first(lock, &waiter)) + __mutex_set_flag(lock, MUTEX_FLAG_WAITERS); + lock_contended(&lock->dep_map, ip); + set_task_state(task, state); for (;;) { /* - * Lets try to take the lock again - this is needed even if - * we get here for the first time (shortly after failing to - * acquire the lock), to make sure that we get a wakeup once - * it's unlocked. Later on, if we sleep, this is the - * operation that gives us the lock. We xchg it to -1, so - * that when we release the lock, we properly wake up the - * other waiters. We only attempt the xchg if the count is - * non-negative in order to avoid unnecessary xchg operations: + * Once we hold wait_lock, we're serialized against + * mutex_unlock() handing the lock off to us, do a trylock + * before testing the error conditions to make sure we pick up + * the handoff. */ - if (atomic_read(&lock->count) >= 0 && - (atomic_xchg_acquire(&lock->count, -1) == 1)) - break; + if (__mutex_trylock(lock, first)) + goto acquired; /* - * got a signal? (This code gets eliminated in the - * TASK_UNINTERRUPTIBLE case.) + * Check for signals and wound conditions while holding + * wait_lock. This ensures the lock cancellation is ordered + * against mutex_unlock() and wake-ups do not go missing. */ if (unlikely(signal_pending_state(state, task))) { ret = -EINTR; @@ -575,36 +685,49 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, goto err; } - __set_task_state(task, state); - - /* didn't get the lock, go to sleep: */ spin_unlock_mutex(&lock->wait_lock, flags); schedule_preempt_disabled(); + + if (!first && __mutex_waiter_is_first(lock, &waiter)) { + first = true; + __mutex_set_flag(lock, MUTEX_FLAG_HANDOFF); + } + + set_task_state(task, state); + /* + * Here we order against unlock; we must either see it change + * state back to RUNNING and fall through the next schedule(), + * or we must see its unlock and acquire. + */ + if ((first && mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx, true)) || + __mutex_trylock(lock, first)) + break; + spin_lock_mutex(&lock->wait_lock, flags); } + spin_lock_mutex(&lock->wait_lock, flags); +acquired: __set_task_state(task, TASK_RUNNING); mutex_remove_waiter(lock, &waiter, task); - /* set it to 0 if there are no waiters left: */ if (likely(list_empty(&lock->wait_list))) - atomic_set(&lock->count, 0); + __mutex_clear_flag(lock, MUTEX_FLAGS); + debug_mutex_free_waiter(&waiter); skip_wait: /* got the lock - cleanup and rejoice! */ lock_acquired(&lock->dep_map, ip); - mutex_set_owner(lock); - if (use_ww_ctx) { - struct ww_mutex *ww = container_of(lock, struct ww_mutex, base); + if (use_ww_ctx) ww_mutex_set_context_slowpath(ww, ww_ctx); - } spin_unlock_mutex(&lock->wait_lock, flags); preempt_enable(); return 0; err: + __set_task_state(task, TASK_RUNNING); mutex_remove_waiter(lock, &waiter, task); spin_unlock_mutex(&lock->wait_lock, flags); debug_mutex_free_waiter(&waiter); @@ -631,7 +754,6 @@ _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest) __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, nest, _RET_IP_, NULL, 0); } - EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock); int __sched @@ -650,7 +772,6 @@ mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass) return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, subclass, NULL, _RET_IP_, NULL, 0); } - EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested); static inline int @@ -715,54 +836,64 @@ EXPORT_SYMBOL_GPL(__ww_mutex_lock_interruptible); /* * Release the lock, slowpath: */ -static inline void -__mutex_unlock_common_slowpath(struct mutex *lock, int nested) +static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigned long ip) { - unsigned long flags; + struct task_struct *next = NULL; + unsigned long owner, flags; WAKE_Q(wake_q); + mutex_release(&lock->dep_map, 1, ip); + /* - * As a performance measurement, release the lock before doing other - * wakeup related duties to follow. This allows other tasks to acquire - * the lock sooner, while still handling cleanups in past unlock calls. - * This can be done as we do not enforce strict equivalence between the - * mutex counter and wait_list. - * + * Release the lock before (potentially) taking the spinlock such that + * other contenders can get on with things ASAP. * - * Some architectures leave the lock unlocked in the fastpath failure - * case, others need to leave it locked. In the later case we have to - * unlock it here - as the lock counter is currently 0 or negative. + * Except when HANDOFF, in that case we must not clear the owner field, + * but instead set it to the top waiter. */ - if (__mutex_slowpath_needs_to_unlock()) - atomic_set(&lock->count, 1); + owner = atomic_long_read(&lock->owner); + for (;;) { + unsigned long old; + +#ifdef CONFIG_DEBUG_MUTEXES + DEBUG_LOCKS_WARN_ON(__owner_task(owner) != current); +#endif + + if (owner & MUTEX_FLAG_HANDOFF) + break; + + old = atomic_long_cmpxchg_release(&lock->owner, owner, + __owner_flags(owner)); + if (old == owner) { + if (owner & MUTEX_FLAG_WAITERS) + break; + + return; + } + + owner = old; + } spin_lock_mutex(&lock->wait_lock, flags); - mutex_release(&lock->dep_map, nested, _RET_IP_); debug_mutex_unlock(lock); - if (!list_empty(&lock->wait_list)) { /* get the first entry from the wait-list: */ struct mutex_waiter *waiter = - list_entry(lock->wait_list.next, - struct mutex_waiter, list); + list_first_entry(&lock->wait_list, + struct mutex_waiter, list); + + next = waiter->task; debug_mutex_wake_waiter(lock, waiter); - wake_q_add(&wake_q, waiter->task); + wake_q_add(&wake_q, next); } - spin_unlock_mutex(&lock->wait_lock, flags); - wake_up_q(&wake_q); -} + if (owner & MUTEX_FLAG_HANDOFF) + __mutex_handoff(lock, next); -/* - * Release the lock, slowpath: - */ -__visible void -__mutex_unlock_slowpath(atomic_t *lock_count) -{ - struct mutex *lock = container_of(lock_count, struct mutex, count); + spin_unlock_mutex(&lock->wait_lock, flags); - __mutex_unlock_common_slowpath(lock, 1); + wake_up_q(&wake_q); } #ifndef CONFIG_DEBUG_LOCK_ALLOC @@ -789,38 +920,30 @@ __mutex_lock_interruptible_slowpath(struct mutex *lock); */ int __sched mutex_lock_interruptible(struct mutex *lock) { - int ret; - might_sleep(); - ret = __mutex_fastpath_lock_retval(&lock->count); - if (likely(!ret)) { - mutex_set_owner(lock); + + if (__mutex_trylock_fast(lock)) return 0; - } else - return __mutex_lock_interruptible_slowpath(lock); + + return __mutex_lock_interruptible_slowpath(lock); } EXPORT_SYMBOL(mutex_lock_interruptible); int __sched mutex_lock_killable(struct mutex *lock) { - int ret; - might_sleep(); - ret = __mutex_fastpath_lock_retval(&lock->count); - if (likely(!ret)) { - mutex_set_owner(lock); + + if (__mutex_trylock_fast(lock)) return 0; - } else - return __mutex_lock_killable_slowpath(lock); + + return __mutex_lock_killable_slowpath(lock); } EXPORT_SYMBOL(mutex_lock_killable); -__visible void __sched -__mutex_lock_slowpath(atomic_t *lock_count) +static noinline void __sched +__mutex_lock_slowpath(struct mutex *lock) { - struct mutex *lock = container_of(lock_count, struct mutex, count); - __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_, NULL, 0); } @@ -856,37 +979,6 @@ __ww_mutex_lock_interruptible_slowpath(struct ww_mutex *lock, #endif -/* - * Spinlock based trylock, we take the spinlock and check whether we - * can get the lock: - */ -static inline int __mutex_trylock_slowpath(atomic_t *lock_count) -{ - struct mutex *lock = container_of(lock_count, struct mutex, count); - unsigned long flags; - int prev; - - /* No need to trylock if the mutex is locked. */ - if (mutex_is_locked(lock)) - return 0; - - spin_lock_mutex(&lock->wait_lock, flags); - - prev = atomic_xchg_acquire(&lock->count, -1); - if (likely(prev == 1)) { - mutex_set_owner(lock); - mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_); - } - - /* Set it back to 0 if there are no waiters: */ - if (likely(list_empty(&lock->wait_list))) - atomic_set(&lock->count, 0); - - spin_unlock_mutex(&lock->wait_lock, flags); - - return prev == 1; -} - /** * mutex_trylock - try to acquire the mutex, without waiting * @lock: the mutex to be acquired @@ -903,13 +995,12 @@ static inline int __mutex_trylock_slowpath(atomic_t *lock_count) */ int __sched mutex_trylock(struct mutex *lock) { - int ret; + bool locked = __mutex_trylock(lock, false); - ret = __mutex_fastpath_trylock(&lock->count, __mutex_trylock_slowpath); - if (ret) - mutex_set_owner(lock); + if (locked) + mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_); - return ret; + return locked; } EXPORT_SYMBOL(mutex_trylock); @@ -917,36 +1008,28 @@ EXPORT_SYMBOL(mutex_trylock); int __sched __ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) { - int ret; - might_sleep(); - ret = __mutex_fastpath_lock_retval(&lock->base.count); - - if (likely(!ret)) { + if (__mutex_trylock_fast(&lock->base)) { ww_mutex_set_context_fastpath(lock, ctx); - mutex_set_owner(&lock->base); - } else - ret = __ww_mutex_lock_slowpath(lock, ctx); - return ret; + return 0; + } + + return __ww_mutex_lock_slowpath(lock, ctx); } EXPORT_SYMBOL(__ww_mutex_lock); int __sched __ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) { - int ret; - might_sleep(); - ret = __mutex_fastpath_lock_retval(&lock->base.count); - - if (likely(!ret)) { + if (__mutex_trylock_fast(&lock->base)) { ww_mutex_set_context_fastpath(lock, ctx); - mutex_set_owner(&lock->base); - } else - ret = __ww_mutex_lock_interruptible_slowpath(lock, ctx); - return ret; + return 0; + } + + return __ww_mutex_lock_interruptible_slowpath(lock, ctx); } EXPORT_SYMBOL(__ww_mutex_lock_interruptible); diff --git a/kernel/locking/mutex.h b/kernel/locking/mutex.h index 6cd6b8e9efd7..4410a4af42a3 100644 --- a/kernel/locking/mutex.h +++ b/kernel/locking/mutex.h @@ -16,32 +16,6 @@ #define mutex_remove_waiter(lock, waiter, task) \ __list_del((waiter)->list.prev, (waiter)->list.next) -#ifdef CONFIG_MUTEX_SPIN_ON_OWNER -/* - * The mutex owner can get read and written to locklessly. - * We should use WRITE_ONCE when writing the owner value to - * avoid store tearing, otherwise, a thread could potentially - * read a partially written and incomplete owner value. - */ -static inline void mutex_set_owner(struct mutex *lock) -{ - WRITE_ONCE(lock->owner, current); -} - -static inline void mutex_clear_owner(struct mutex *lock) -{ - WRITE_ONCE(lock->owner, NULL); -} -#else -static inline void mutex_set_owner(struct mutex *lock) -{ -} - -static inline void mutex_clear_owner(struct mutex *lock) -{ -} -#endif - #define debug_mutex_wake_waiter(lock, waiter) do { } while (0) #define debug_mutex_free_waiter(waiter) do { } while (0) #define debug_mutex_add_waiter(lock, waiter, ti) do { } while (0) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 154fd689fe02..8b08fb257856 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -75,11 +75,11 @@ #include <linux/compiler.h> #include <linux/frame.h> #include <linux/prefetch.h> +#include <linux/mutex.h> #include <asm/switch_to.h> #include <asm/tlb.h> #include <asm/irq_regs.h> -#include <asm/mutex.h> #ifdef CONFIG_PARAVIRT #include <asm/paravirt.h> #endif |