From 3660c2813fb6d0ba48ee44bcbf9feddf7218c11d Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 3 Dec 2013 09:24:02 -0800 Subject: rcu: Add ACCESS_ONCE() to ->n_force_qs_lh accesses The ->n_force_qs_lh field is accessed without the benefit of any synchronization, so this commit adds the needed ACCESS_ONCE() wrappers. Yes, increments to ->n_force_qs_lh can be lost, but contention should be low and the field is strictly statistical in nature, so this is not a problem. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcu/tree.c | 4 ++-- kernel/rcu/tree_trace.c | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/rcu') diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index b3d116cd072d..e64157798624 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2304,7 +2304,7 @@ static void force_quiescent_state(struct rcu_state *rsp) if (rnp_old != NULL) raw_spin_unlock(&rnp_old->fqslock); if (ret) { - rsp->n_force_qs_lh++; + ACCESS_ONCE(rsp->n_force_qs_lh)++; return; } rnp_old = rnp; @@ -2316,7 +2316,7 @@ static void force_quiescent_state(struct rcu_state *rsp) smp_mb__after_unlock_lock(); raw_spin_unlock(&rnp_old->fqslock); if (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) { - rsp->n_force_qs_lh++; + ACCESS_ONCE(rsp->n_force_qs_lh)++; raw_spin_unlock_irqrestore(&rnp_old->lock, flags); return; /* Someone beat us to it. */ } diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c index 4def475336d4..d1f1e64a6d72 100644 --- a/kernel/rcu/tree_trace.c +++ b/kernel/rcu/tree_trace.c @@ -273,7 +273,7 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp) seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n", rsp->n_force_qs, rsp->n_force_qs_ngp, rsp->n_force_qs - rsp->n_force_qs_ngp, - rsp->n_force_qs_lh, rsp->qlen_lazy, rsp->qlen); + ACCESS_ONCE(rsp->n_force_qs_lh), rsp->qlen_lazy, rsp->qlen); for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) { if (rnp->level != level) { seq_puts(m, "\n"); -- cgit v1.2.3 From 87de1cfdc55b16b794e245b07322340725149d62 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 3 Dec 2013 10:02:52 -0800 Subject: rcu: Stop tracking FSF's postal address All of the RCU source files have the usual GPL header, which contains a long-obsolete postal address for FSF. To avoid the need to track the FSF office's movements, this commit substitutes the URL where GPL may be found. Reported-by: Greg KH Reported-by: Steven Rostedt Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- include/linux/rcupdate.h | 4 ++-- include/linux/rcutiny.h | 4 ++-- include/linux/rcutree.h | 4 ++-- include/linux/srcu.h | 4 ++-- kernel/rcu/rcu.h | 4 ++-- kernel/rcu/srcu.c | 4 ++-- kernel/rcu/tiny.c | 4 ++-- kernel/rcu/tiny_plugin.h | 4 ++-- kernel/rcu/torture.c | 4 ++-- kernel/rcu/tree.c | 4 ++-- kernel/rcu/tree.h | 4 ++-- kernel/rcu/tree_plugin.h | 4 ++-- kernel/rcu/tree_trace.c | 4 ++-- kernel/rcu/update.c | 4 ++-- 14 files changed, 28 insertions(+), 28 deletions(-) (limited to 'kernel/rcu') diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 72bf3a01a4ee..b200756ea4c0 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -12,8 +12,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright IBM Corporation, 2001 * diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 6f01771b571c..c364e9148de2 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -12,8 +12,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright IBM Corporation, 2008 * diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 72137ee8c603..08b084068967 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -12,8 +12,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright IBM Corporation, 2008 * diff --git a/include/linux/srcu.h b/include/linux/srcu.h index 9b058eecd403..a2783cb5d275 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -12,8 +12,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright (C) IBM Corporation, 2006 * Copyright (C) Fujitsu, 2012 diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 79c3877e9c5b..1bd787fddcb2 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -12,8 +12,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright IBM Corporation, 2011 * diff --git a/kernel/rcu/srcu.c b/kernel/rcu/srcu.c index 3318d8284384..5db7e9272d37 100644 --- a/kernel/rcu/srcu.c +++ b/kernel/rcu/srcu.c @@ -12,8 +12,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright (C) IBM Corporation, 2006 * Copyright (C) Fujitsu, 2012 diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c index 1254f312d024..53b95bbf4abb 100644 --- a/kernel/rcu/tiny.c +++ b/kernel/rcu/tiny.c @@ -12,8 +12,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright IBM Corporation, 2008 * diff --git a/kernel/rcu/tiny_plugin.h b/kernel/rcu/tiny_plugin.h index 280d06cae352..431528520562 100644 --- a/kernel/rcu/tiny_plugin.h +++ b/kernel/rcu/tiny_plugin.h @@ -14,8 +14,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright (c) 2010 Linaro * diff --git a/kernel/rcu/torture.c b/kernel/rcu/torture.c index 732f8ae3086a..ab7dd192a50b 100644 --- a/kernel/rcu/torture.c +++ b/kernel/rcu/torture.c @@ -12,8 +12,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright (C) IBM Corporation, 2005, 2006 * diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index e64157798624..321feef0f5c0 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -12,8 +12,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright IBM Corporation, 2008 * diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 8c19873f1ac9..75dc3c39a02a 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -13,8 +13,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright IBM Corporation, 2008 * diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 6e2ef4b2b920..f9b9cdd36c8d 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -14,8 +14,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright Red Hat, 2009 * Copyright IBM Corporation, 2009 diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c index d1f1e64a6d72..5cdc62e1beeb 100644 --- a/kernel/rcu/tree_trace.c +++ b/kernel/rcu/tree_trace.c @@ -12,8 +12,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright IBM Corporation, 2008 * diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index c54609faf233..fd0d5b5b8e7c 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -12,8 +12,8 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with this program; if not, you can access it online at + * http://www.gnu.org/licenses/gpl-2.0.html. * * Copyright IBM Corporation, 2001 * -- cgit v1.2.3 From cb1e78cfa267453bb19e7edafd214c03834b664c Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 4 Dec 2013 18:42:03 -0800 Subject: rcu: Remove ACCESS_ONCE() from jiffies Because jiffies is one of a very few variables marked "volatile", there is no need to use ACCESS_ONCE() when accessing it. This commit therefore removes the redundant ACCESS_ONCE() wrappers. Reported by: Eric Dumazet Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcu/torture.c | 4 ++-- kernel/rcu/tree.c | 6 +++--- 2 files changed, 5 insertions(+), 5 deletions(-) (limited to 'kernel/rcu') diff --git a/kernel/rcu/torture.c b/kernel/rcu/torture.c index ab7dd192a50b..022c5312b725 100644 --- a/kernel/rcu/torture.c +++ b/kernel/rcu/torture.c @@ -1352,7 +1352,7 @@ rcu_torture_shutdown(void *arg) unsigned long jiffies_snap; VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started"); - jiffies_snap = ACCESS_ONCE(jiffies); + jiffies_snap = jiffies; while (ULONG_CMP_LT(jiffies_snap, shutdown_time) && !kthread_should_stop()) { delta = shutdown_time - jiffies_snap; @@ -1361,7 +1361,7 @@ rcu_torture_shutdown(void *arg) "rcu_torture_shutdown task: %lu jiffies remaining\n", torture_type, delta); schedule_timeout_interruptible(delta); - jiffies_snap = ACCESS_ONCE(jiffies); + jiffies_snap = jiffies; } if (kthread_should_stop()) { VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping"); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 321feef0f5c0..73c3cd2b87ac 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -837,7 +837,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp, * to the next. Only do this for the primary flavor of RCU. */ if (rdp->rsp == rcu_state && - ULONG_CMP_GE(ACCESS_ONCE(jiffies), rdp->rsp->jiffies_resched)) { + ULONG_CMP_GE(jiffies, rdp->rsp->jiffies_resched)) { rdp->rsp->jiffies_resched += 5; resched_cpu(rdp->cpu); } @@ -847,7 +847,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp, static void record_gp_stall_check_time(struct rcu_state *rsp) { - unsigned long j = ACCESS_ONCE(jiffies); + unsigned long j = jiffies; unsigned long j1; rsp->gp_start = j; @@ -1005,7 +1005,7 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) if (rcu_cpu_stall_suppress || !rcu_gp_in_progress(rsp)) return; - j = ACCESS_ONCE(jiffies); + j = jiffies; /* * Lots of memory barriers to reject false positives. -- cgit v1.2.3 From 52e2bb958ac4f9b3c4bdd78606d279852fd72922 Mon Sep 17 00:00:00 2001 From: Paul Bolle Date: Sun, 9 Feb 2014 14:35:11 +0100 Subject: rcu: Disambiguate CONFIG_RCU_NOCB_CPUs This commit fixes a grammar issue in the rcu_nohz_full_cpu() comment header, so that it is clear that the plural is CPUs not Kconfig options. Signed-off-by: Paul Bolle Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcu/tree_plugin.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/rcu') diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index f9b9cdd36c8d..fffe4178a23d 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2893,7 +2893,7 @@ static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp) * CPU unless the grace period has extended for too long. * * This code relies on the fact that all NO_HZ_FULL CPUs are also - * CONFIG_RCU_NOCB_CPUs. + * CONFIG_RCU_NOCB_CPU CPUs. */ static bool rcu_nohz_full_cpu(struct rcu_state *rsp) { -- cgit v1.2.3 From ae1670339c95c3ff96ab10582506cf827c5fecc8 Mon Sep 17 00:00:00 2001 From: Shaibal Dutta Date: Fri, 31 Jan 2014 11:53:06 -0800 Subject: rcu: Move SRCU grace period work to power efficient workqueue For better use of CPU idle time, allow the scheduler to select the CPU on which the SRCU grace period work would be scheduled. This improves idle residency time and conserves power. This functionality is enabled when CONFIG_WQ_POWER_EFFICIENT is selected. Cc: Lai Jiangshan Cc: "Paul E. McKenney" Cc: Dipankar Sarma Signed-off-by: Shaibal Dutta [zoran.markovic@linaro.org: Rebased to latest kernel version. Added commit message. Fixed code alignment.] Signed-off-by: Zoran Markovic Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcu/srcu.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'kernel/rcu') diff --git a/kernel/rcu/srcu.c b/kernel/rcu/srcu.c index 5db7e9272d37..2359779e1daa 100644 --- a/kernel/rcu/srcu.c +++ b/kernel/rcu/srcu.c @@ -398,7 +398,7 @@ void call_srcu(struct srcu_struct *sp, struct rcu_head *head, rcu_batch_queue(&sp->batch_queue, head); if (!sp->running) { sp->running = true; - schedule_delayed_work(&sp->work, 0); + queue_delayed_work(system_power_efficient_wq, &sp->work, 0); } spin_unlock_irqrestore(&sp->queue_lock, flags); } @@ -674,7 +674,8 @@ static void srcu_reschedule(struct srcu_struct *sp) } if (pending) - schedule_delayed_work(&sp->work, SRCU_INTERVAL); + queue_delayed_work(system_power_efficient_wq, + &sp->work, SRCU_INTERVAL); } /* -- cgit v1.2.3 From 2f33b512a5460578f6cf11d7b7867bed53157c7c Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 17 Nov 2013 18:25:48 -0800 Subject: rcu: Optimize rcu_is_nocb_cpu() for RCU_NOCB_CPU_ALL If CONFIG_RCU_NOCB_CPU_ALL=y, then rcu_is_nocb_cpu() will always return true, however, the current version nevertheless checks rcu_nocb_mask. This commit therefore creates a static inline implementation of rcu_is_nocb_cpu() that unconditionally returns true when CONFIG_RCU_NOCB_CPU_ALL=y. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- include/linux/rcupdate.h | 6 ++++-- kernel/rcu/tree_plugin.h | 2 ++ 2 files changed, 6 insertions(+), 2 deletions(-) (limited to 'kernel/rcu') diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 72bf3a01a4ee..281c90f8989e 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -1015,11 +1015,13 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) #define kfree_rcu(ptr, rcu_head) \ __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head)) -#ifdef CONFIG_RCU_NOCB_CPU +#if defined(CONFIG_RCU_NOCB_CPU_ALL) +static inline bool rcu_is_nocb_cpu(int cpu) { return true; } +#elif defined(CONFIG_RCU_NOCB_CPU) bool rcu_is_nocb_cpu(int cpu); #else static inline bool rcu_is_nocb_cpu(int cpu) { return false; } -#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */ +#endif /* Only for use by adaptive-ticks code. */ diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 6e2ef4b2b920..39a50b918bff 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2101,6 +2101,7 @@ static void rcu_init_one_nocb(struct rcu_node *rnp) init_waitqueue_head(&rnp->nocb_gp_wq[1]); } +#ifndef CONFIG_RCU_NOCB_CPU_ALL /* Is the specified CPU a no-CPUs CPU? */ bool rcu_is_nocb_cpu(int cpu) { @@ -2108,6 +2109,7 @@ bool rcu_is_nocb_cpu(int cpu) return cpumask_test_cpu(cpu, rcu_nocb_mask); return false; } +#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */ /* * Enqueue the specified string of rcu_head structures onto the specified -- cgit v1.2.3 From ffa83fb565fbc397cbafb4b71fd1cce276d4c3b6 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 17 Nov 2013 19:27:16 -0800 Subject: rcu: Optimize rcu_needs_cpu() for RCU_NOCB_CPU_ALL If CONFIG_RCU_NOCB_CPU_ALL=y, then rcu_needs_cpu() will always return false, however, the current version nevertheless checks for RCU callbacks. This commit therefore creates a static inline implementation of rcu_needs_cpu() that unconditionally returns false when CONFIG_RCU_NOCB_CPU_ALL=y. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- include/linux/rcupdate.h | 8 ++++++++ include/linux/rcutiny.h | 6 ------ include/linux/rcutree.h | 2 ++ kernel/rcu/tree.c | 2 +- kernel/rcu/tree_plugin.h | 4 ++++ 5 files changed, 15 insertions(+), 7 deletions(-) (limited to 'kernel/rcu') diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 281c90f8989e..5f7d5f410d50 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -1015,6 +1015,14 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) #define kfree_rcu(ptr, rcu_head) \ __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head)) +#if defined(CONFIG_TINY_RCU) || defined(CONFIG_RCU_NOCB_CPU_ALL) +static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies) +{ + *delta_jiffies = ULONG_MAX; + return 0; +} +#endif /* #if defined(CONFIG_TINY_RCU) || defined(CONFIG_RCU_NOCB_CPU_ALL) */ + #if defined(CONFIG_RCU_NOCB_CPU_ALL) static inline bool rcu_is_nocb_cpu(int cpu) { return true; } #elif defined(CONFIG_RCU_NOCB_CPU) diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 6f01771b571c..9524903487d0 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -68,12 +68,6 @@ static inline void kfree_call_rcu(struct rcu_head *head, call_rcu(head, func); } -static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies) -{ - *delta_jiffies = ULONG_MAX; - return 0; -} - static inline void rcu_note_context_switch(int cpu) { rcu_sched_qs(cpu); diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 72137ee8c603..81198c84e268 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -31,7 +31,9 @@ #define __LINUX_RCUTREE_H void rcu_note_context_switch(int cpu); +#ifndef CONFIG_RCU_NOCB_CPU_ALL int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies); +#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */ void rcu_cpu_stall_reset(void); /* diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index b3d116cd072d..c2c8234a0291 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2880,7 +2880,7 @@ static int rcu_pending(int cpu) * non-NULL, store an indication of whether all callbacks are lazy. * (If there are no callbacks, all of them are deemed to be lazy.) */ -static int rcu_cpu_has_callbacks(int cpu, bool *all_lazy) +static int __maybe_unused rcu_cpu_has_callbacks(int cpu, bool *all_lazy) { bool al = true; bool hc = false; diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 39a50b918bff..820b06aefbee 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1586,11 +1586,13 @@ static void rcu_prepare_kthreads(int cpu) * Because we not have RCU_FAST_NO_HZ, just check whether this CPU needs * any flavor of RCU. */ +#ifndef CONFIG_RCU_NOCB_CPU_ALL int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies) { *delta_jiffies = ULONG_MAX; return rcu_cpu_has_callbacks(cpu, NULL); } +#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */ /* * Because we do not have RCU_FAST_NO_HZ, don't bother cleaning up @@ -1696,6 +1698,7 @@ static bool rcu_try_advance_all_cbs(void) * * The caller must have disabled interrupts. */ +#ifndef CONFIG_RCU_NOCB_CPU_ALL int rcu_needs_cpu(int cpu, unsigned long *dj) { struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu); @@ -1726,6 +1729,7 @@ int rcu_needs_cpu(int cpu, unsigned long *dj) } return 0; } +#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */ /* * Prepare a CPU for idle from an RCU perspective. The first major task -- cgit v1.2.3 From f1f399d1281ea339a08469f7e58193624992f620 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 17 Nov 2013 21:08:07 -0800 Subject: rcu: Optimize RCU_FAST_NO_HZ for RCU_NOCB_CPU_ALL If CONFIG_RCU_NOCB_CPU_ALL=y, then no CPU will ever have RCU callbacks because these callbacks will instead be handled by the rcuo kthreads. However, the current version of RCU_FAST_NO_HZ nevertheless checks for RCU callbacks. This commit therefore creates static inline implementations of rcu_prepare_for_idle() and rcu_cleanup_after_idle() that are no-ops when CONFIG_RCU_NOCB_CPU_ALL=y. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcu/tree_plugin.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'kernel/rcu') diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 820b06aefbee..41afc3fbfb6c 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1658,7 +1658,7 @@ extern int tick_nohz_active; * only if it has been awhile since the last time we did so. Afterwards, * if there are any callbacks ready for immediate invocation, return true. */ -static bool rcu_try_advance_all_cbs(void) +static bool __maybe_unused rcu_try_advance_all_cbs(void) { bool cbs_ready = false; struct rcu_data *rdp; @@ -1743,6 +1743,7 @@ int rcu_needs_cpu(int cpu, unsigned long *dj) */ static void rcu_prepare_for_idle(int cpu) { +#ifndef CONFIG_RCU_NOCB_CPU_ALL struct rcu_data *rdp; struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu); struct rcu_node *rnp; @@ -1794,6 +1795,7 @@ static void rcu_prepare_for_idle(int cpu) rcu_accelerate_cbs(rsp, rnp, rdp); raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ } +#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */ } /* @@ -1803,11 +1805,12 @@ static void rcu_prepare_for_idle(int cpu) */ static void rcu_cleanup_after_idle(int cpu) { - +#ifndef CONFIG_RCU_NOCB_CPU_ALL if (rcu_is_nocb_cpu(cpu)) return; if (rcu_try_advance_all_cbs()) invoke_rcu_core(); +#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */ } /* -- cgit v1.2.3 From 7a754743185a4b05818e10058fa2fbe4e6969085 Mon Sep 17 00:00:00 2001 From: Paul Gortmaker Date: Tue, 11 Feb 2014 16:10:12 -0500 Subject: rcu: Fix sparse warning for rcu_expedited from kernel/ksysfs.c This commit fixes the follwoing warning: kernel/ksysfs.c:143:5: warning: symbol 'rcu_expedited' was not declared. Should it be static? Signed-off-by: Paul Gortmaker [ paulmck: Moved the declaration to include/linux/rcupdate.h to avoid including the RCU-internal rcu.h file outside of RCU. ] Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- include/linux/rcupdate.h | 1 + kernel/ksysfs.c | 2 ++ kernel/rcu/rcu.h | 2 -- 3 files changed, 3 insertions(+), 2 deletions(-) (limited to 'kernel/rcu') diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 32decf1a9c6c..f3706c6b2e21 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -46,6 +46,7 @@ #include #include +extern int rcu_expedited; /* for sysctl */ #ifdef CONFIG_RCU_TORTURE_TEST extern int rcutorture_runnable; /* for sysctl */ #endif /* #ifdef CONFIG_RCU_TORTURE_TEST */ diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c index d945a949760f..e660964086e2 100644 --- a/kernel/ksysfs.c +++ b/kernel/ksysfs.c @@ -19,6 +19,8 @@ #include #include +#include /* rcu_expedited */ + #define KERNEL_ATTR_RO(_name) \ static struct kobj_attribute _name##_attr = __ATTR_RO(_name) diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 1bd787fddcb2..af2e60a8425d 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -116,8 +116,6 @@ static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head) } } -extern int rcu_expedited; - #ifdef CONFIG_RCU_STALL_COMMON extern int rcu_cpu_stall_suppress; -- cgit v1.2.3 From 5cb5c6e18f822b19bd41a2c0f9930c82b3ec0bc9 Mon Sep 17 00:00:00 2001 From: Paul Gortmaker Date: Wed, 19 Feb 2014 14:33:27 -0500 Subject: rcu: Ensure kernel/rcu/rcu.h can be sourced/used stand-alone The kbuild test bot uncovered an implicit dependence on the trace header being present before rcu.h in ia64 allmodconfig that looks like this: In file included from kernel/ksysfs.c:22:0: kernel/rcu/rcu.h: In function '__rcu_reclaim': kernel/rcu/rcu.h:107:3: error: implicit declaration of function 'trace_rcu_invoke_kfree_callback' [-Werror=implicit-function-declaration] kernel/rcu/rcu.h:112:3: error: implicit declaration of function 'trace_rcu_invoke_callback' [-Werror=implicit-function-declaration] cc1: some warnings being treated as errors Looking at other rcu.h users, we can find that they all were sourcing the trace header in advance of rcu.h itself, as seen in the context of this diff. There were also some inconsistencies as to whether it was or wasn't sourced based on the parent tracing Kconfig. Rather than "fix" it at each use site, and have inconsistent use based on whether "#ifdef CONFIG_RCU_TRACE" was used or not, lets just source the trace header just once, in the actual consumer of it, which is rcu.h itself. We include it unconditionally, as build testing shows us that is a hard requirement for some files. Reported-by: kbuild test robot Signed-off-by: Paul Gortmaker Signed-off-by: Paul E. McKenney --- kernel/rcu/rcu.h | 1 + kernel/rcu/srcu.c | 2 -- kernel/rcu/tiny.c | 4 ---- kernel/rcu/tree.c | 2 -- kernel/rcu/update.c | 1 - 5 files changed, 1 insertion(+), 9 deletions(-) (limited to 'kernel/rcu') diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index af2e60a8425d..bfda2726ca45 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -23,6 +23,7 @@ #ifndef __LINUX_RCU_H #define __LINUX_RCU_H +#include #ifdef CONFIG_RCU_TRACE #define RCU_TRACE(stmt) stmt #else /* #ifdef CONFIG_RCU_TRACE */ diff --git a/kernel/rcu/srcu.c b/kernel/rcu/srcu.c index 2359779e1daa..c639556f3fa0 100644 --- a/kernel/rcu/srcu.c +++ b/kernel/rcu/srcu.c @@ -36,8 +36,6 @@ #include #include -#include - #include "rcu.h" /* diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c index 53b95bbf4abb..d9efcc13008c 100644 --- a/kernel/rcu/tiny.c +++ b/kernel/rcu/tiny.c @@ -37,10 +37,6 @@ #include #include -#ifdef CONFIG_RCU_TRACE -#include -#endif /* #else #ifdef CONFIG_RCU_TRACE */ - #include "rcu.h" /* Forward declarations for tiny_plugin.h. */ diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 73c3cd2b87ac..c7ed5db2dd79 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -58,8 +58,6 @@ #include #include "tree.h" -#include - #include "rcu.h" MODULE_ALIAS("rcutree"); diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index fd0d5b5b8e7c..4c0a9b0af469 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -49,7 +49,6 @@ #include #define CREATE_TRACE_POINTS -#include #include "rcu.h" -- cgit v1.2.3