From 8f553c498e1772cccb39a114da4a498d22992758 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 24 May 2017 10:15:12 +0200
Subject: cpu/hotplug: Provide cpus_read|write_[un]lock()
The counting 'rwsem' hackery of get|put_online_cpus() is going to be
replaced by percpu rwsem.
Rename the functions to make it clear that it's locking and not some
refcount style interface. These new functions will be used for the
preparatory patches which make the code ready for the percpu rwsem
conversion.
Rename all instances in the cpu hotplug code while at it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081547.080397752@linutronix.de
---
include/linux/cpu.h | 34 +++++++++++++++++++---------------
1 file changed, 19 insertions(+), 15 deletions(-)
(limited to 'include/linux')
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index f92081234afd..055876003914 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -99,26 +99,30 @@ static inline void cpu_maps_update_done(void)
extern struct bus_type cpu_subsys;
#ifdef CONFIG_HOTPLUG_CPU
-/* Stop CPUs going up and down. */
-
-extern void cpu_hotplug_begin(void);
-extern void cpu_hotplug_done(void);
-extern void get_online_cpus(void);
-extern void put_online_cpus(void);
+extern void cpus_write_lock(void);
+extern void cpus_write_unlock(void);
+extern void cpus_read_lock(void);
+extern void cpus_read_unlock(void);
extern void cpu_hotplug_disable(void);
extern void cpu_hotplug_enable(void);
void clear_tasks_mm_cpumask(int cpu);
int cpu_down(unsigned int cpu);
-#else /* CONFIG_HOTPLUG_CPU */
-
-static inline void cpu_hotplug_begin(void) {}
-static inline void cpu_hotplug_done(void) {}
-#define get_online_cpus() do { } while (0)
-#define put_online_cpus() do { } while (0)
-#define cpu_hotplug_disable() do { } while (0)
-#define cpu_hotplug_enable() do { } while (0)
-#endif /* CONFIG_HOTPLUG_CPU */
+#else /* CONFIG_HOTPLUG_CPU */
+
+static inline void cpus_write_lock(void) { }
+static inline void cpus_write_unlock(void) { }
+static inline void cpus_read_lock(void) { }
+static inline void cpus_read_unlock(void) { }
+static inline void cpu_hotplug_disable(void) { }
+static inline void cpu_hotplug_enable(void) { }
+#endif /* !CONFIG_HOTPLUG_CPU */
+
+/* Wrappers which go away once all code is converted */
+static inline void cpu_hotplug_begin(void) { cpus_write_lock(); }
+static inline void cpu_hotplug_done(void) { cpus_write_unlock(); }
+static inline void get_online_cpus(void) { cpus_read_lock(); }
+static inline void put_online_cpus(void) { cpus_read_unlock(); }
#ifdef CONFIG_PM_SLEEP_SMP
extern int freeze_secondary_cpus(int primary);
--
cgit v1.2.3
From ade3f680a76b474d9f5375a9b1d100ee787bf469 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 24 May 2017 10:15:13 +0200
Subject: cpu/hotplug: Provide lockdep_assert_cpus_held()
Provide a stub function which can be used in places where existing
get_online_cpus() calls are moved to call sites.
This stub is going to be filled by the final conversion of the hotplug
locking mechanism to a percpu rwsem.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081547.161282442@linutronix.de
---
include/linux/cpu.h | 2 ++
1 file changed, 2 insertions(+)
(limited to 'include/linux')
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 055876003914..af4d660798e5 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -103,6 +103,7 @@ extern void cpus_write_lock(void);
extern void cpus_write_unlock(void);
extern void cpus_read_lock(void);
extern void cpus_read_unlock(void);
+static inline void lockdep_assert_cpus_held(void) { }
extern void cpu_hotplug_disable(void);
extern void cpu_hotplug_enable(void);
void clear_tasks_mm_cpumask(int cpu);
@@ -114,6 +115,7 @@ static inline void cpus_write_lock(void) { }
static inline void cpus_write_unlock(void) { }
static inline void cpus_read_lock(void) { }
static inline void cpus_read_unlock(void) { }
+static inline void lockdep_assert_cpus_held(void) { }
static inline void cpu_hotplug_disable(void) { }
static inline void cpu_hotplug_enable(void) { }
#endif /* !CONFIG_HOTPLUG_CPU */
--
cgit v1.2.3
From 71def423fe3da0d40ad3427a4cd5f9edc53bff67 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 24 May 2017 10:15:14 +0200
Subject: cpu/hotplug: Provide cpuhp_setup/remove_state[_nocalls]_cpuslocked()
Some call sites of cpuhp_setup/remove_state[_nocalls]() are within a
cpus_read locked region.
cpuhp_setup/remove_state[_nocalls]() call cpus_read_lock() as well, which
is possible in the current implementation but prevents converting the
hotplug locking to a percpu rwsem.
Provide locked versions of the interfaces to avoid nested calls to
cpus_read_lock().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081547.239600868@linutronix.de
---
include/linux/cpuhotplug.h | 29 ++++++++++++++++++++++++++++
kernel/cpu.c | 47 +++++++++++++++++++++++++++++++++++-----------
2 files changed, 65 insertions(+), 11 deletions(-)
(limited to 'include/linux')
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 0f2a80377520..4fac564dde70 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -153,6 +153,11 @@ int __cpuhp_setup_state(enum cpuhp_state state, const char *name, bool invoke,
int (*startup)(unsigned int cpu),
int (*teardown)(unsigned int cpu), bool multi_instance);
+int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state, const char *name,
+ bool invoke,
+ int (*startup)(unsigned int cpu),
+ int (*teardown)(unsigned int cpu),
+ bool multi_instance);
/**
* cpuhp_setup_state - Setup hotplug state callbacks with calling the callbacks
* @state: The state for which the calls are installed
@@ -171,6 +176,15 @@ static inline int cpuhp_setup_state(enum cpuhp_state state,
return __cpuhp_setup_state(state, name, true, startup, teardown, false);
}
+static inline int cpuhp_setup_state_cpuslocked(enum cpuhp_state state,
+ const char *name,
+ int (*startup)(unsigned int cpu),
+ int (*teardown)(unsigned int cpu))
+{
+ return __cpuhp_setup_state_cpuslocked(state, name, true, startup,
+ teardown, false);
+}
+
/**
* cpuhp_setup_state_nocalls - Setup hotplug state callbacks without calling the
* callbacks
@@ -191,6 +205,15 @@ static inline int cpuhp_setup_state_nocalls(enum cpuhp_state state,
false);
}
+static inline int cpuhp_setup_state_nocalls_cpuslocked(enum cpuhp_state state,
+ const char *name,
+ int (*startup)(unsigned int cpu),
+ int (*teardown)(unsigned int cpu))
+{
+ return __cpuhp_setup_state_cpuslocked(state, name, false, startup,
+ teardown, false);
+}
+
/**
* cpuhp_setup_state_multi - Add callbacks for multi state
* @state: The state for which the calls are installed
@@ -250,6 +273,7 @@ static inline int cpuhp_state_add_instance_nocalls(enum cpuhp_state state,
}
void __cpuhp_remove_state(enum cpuhp_state state, bool invoke);
+void __cpuhp_remove_state_cpuslocked(enum cpuhp_state state, bool invoke);
/**
* cpuhp_remove_state - Remove hotplug state callbacks and invoke the teardown
@@ -273,6 +297,11 @@ static inline void cpuhp_remove_state_nocalls(enum cpuhp_state state)
__cpuhp_remove_state(state, false);
}
+static inline void cpuhp_remove_state_nocalls_cpuslocked(enum cpuhp_state state)
+{
+ __cpuhp_remove_state_cpuslocked(state, false);
+}
+
/**
* cpuhp_remove_multi_state - Remove hotplug multi state callback
* @state: The state for which the calls are removed
diff --git a/kernel/cpu.c b/kernel/cpu.c
index d3221ae5b474..dc27c5a28153 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1459,7 +1459,7 @@ unlock:
EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);
/**
- * __cpuhp_setup_state - Setup the callbacks for an hotplug machine state
+ * __cpuhp_setup_state_cpuslocked - Setup the callbacks for an hotplug machine state
* @state: The state to setup
* @invoke: If true, the startup function is invoked for cpus where
* cpu state >= @state
@@ -1468,25 +1468,27 @@ EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);
* @multi_instance: State is set up for multiple instances which get
* added afterwards.
*
+ * The caller needs to hold cpus read locked while calling this function.
* Returns:
* On success:
* Positive state number if @state is CPUHP_AP_ONLINE_DYN
* 0 for all other states
* On failure: proper (negative) error code
*/
-int __cpuhp_setup_state(enum cpuhp_state state,
- const char *name, bool invoke,
- int (*startup)(unsigned int cpu),
- int (*teardown)(unsigned int cpu),
- bool multi_instance)
+int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state,
+ const char *name, bool invoke,
+ int (*startup)(unsigned int cpu),
+ int (*teardown)(unsigned int cpu),
+ bool multi_instance)
{
int cpu, ret = 0;
bool dynstate;
+ lockdep_assert_cpus_held();
+
if (cpuhp_cb_check(state) || !name)
return -EINVAL;
- cpus_read_lock();
mutex_lock(&cpuhp_state_mutex);
ret = cpuhp_store_callbacks(state, name, startup, teardown,
@@ -1522,7 +1524,6 @@ int __cpuhp_setup_state(enum cpuhp_state state,
}
out:
mutex_unlock(&cpuhp_state_mutex);
- cpus_read_unlock();
/*
* If the requested state is CPUHP_AP_ONLINE_DYN, return the
* dynamically allocated state in case of success.
@@ -1531,6 +1532,22 @@ out:
return state;
return ret;
}
+EXPORT_SYMBOL(__cpuhp_setup_state_cpuslocked);
+
+int __cpuhp_setup_state(enum cpuhp_state state,
+ const char *name, bool invoke,
+ int (*startup)(unsigned int cpu),
+ int (*teardown)(unsigned int cpu),
+ bool multi_instance)
+{
+ int ret;
+
+ cpus_read_lock();
+ ret = __cpuhp_setup_state_cpuslocked(state, name, invoke, startup,
+ teardown, multi_instance);
+ cpus_read_unlock();
+ return ret;
+}
EXPORT_SYMBOL(__cpuhp_setup_state);
int __cpuhp_state_remove_instance(enum cpuhp_state state,
@@ -1572,22 +1589,23 @@ remove:
EXPORT_SYMBOL_GPL(__cpuhp_state_remove_instance);
/**
- * __cpuhp_remove_state - Remove the callbacks for an hotplug machine state
+ * __cpuhp_remove_state_cpuslocked - Remove the callbacks for an hotplug machine state
* @state: The state to remove
* @invoke: If true, the teardown function is invoked for cpus where
* cpu state >= @state
*
+ * The caller needs to hold cpus read locked while calling this function.
* The teardown callback is currently not allowed to fail. Think
* about module removal!
*/
-void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
+void __cpuhp_remove_state_cpuslocked(enum cpuhp_state state, bool invoke)
{
struct cpuhp_step *sp = cpuhp_get_step(state);
int cpu;
BUG_ON(cpuhp_cb_check(state));
- cpus_read_lock();
+ lockdep_assert_cpus_held();
mutex_lock(&cpuhp_state_mutex);
if (sp->multi_instance) {
@@ -1615,6 +1633,13 @@ void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
remove:
cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
mutex_unlock(&cpuhp_state_mutex);
+}
+EXPORT_SYMBOL(__cpuhp_remove_state_cpuslocked);
+
+void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
+{
+ cpus_read_lock();
+ __cpuhp_remove_state_cpuslocked(state, invoke);
cpus_read_unlock();
}
EXPORT_SYMBOL(__cpuhp_remove_state);
--
cgit v1.2.3
From 9805c6733349ea3ccd22cf75b8ebaabb5290e310 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 24 May 2017 10:15:15 +0200
Subject: cpu/hotplug: Add __cpuhp_state_add_instance_cpuslocked()
Add cpuslocked() variants for the multi instance registration so this can
be called from a cpus_read_lock() protected region.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081547.321782217@linutronix.de
---
include/linux/cpuhotplug.h | 9 +++++++++
kernel/cpu.c | 18 +++++++++++++++---
2 files changed, 24 insertions(+), 3 deletions(-)
(limited to 'include/linux')
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 4fac564dde70..df3d2719a796 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -240,6 +240,8 @@ static inline int cpuhp_setup_state_multi(enum cpuhp_state state,
int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
bool invoke);
+int __cpuhp_state_add_instance_cpuslocked(enum cpuhp_state state,
+ struct hlist_node *node, bool invoke);
/**
* cpuhp_state_add_instance - Add an instance for a state and invoke startup
@@ -272,6 +274,13 @@ static inline int cpuhp_state_add_instance_nocalls(enum cpuhp_state state,
return __cpuhp_state_add_instance(state, node, false);
}
+static inline int
+cpuhp_state_add_instance_nocalls_cpuslocked(enum cpuhp_state state,
+ struct hlist_node *node)
+{
+ return __cpuhp_state_add_instance_cpuslocked(state, node, false);
+}
+
void __cpuhp_remove_state(enum cpuhp_state state, bool invoke);
void __cpuhp_remove_state_cpuslocked(enum cpuhp_state state, bool invoke);
diff --git a/kernel/cpu.c b/kernel/cpu.c
index dc27c5a28153..e4389ac55b65 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1413,18 +1413,20 @@ static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state,
}
}
-int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
- bool invoke)
+int __cpuhp_state_add_instance_cpuslocked(enum cpuhp_state state,
+ struct hlist_node *node,
+ bool invoke)
{
struct cpuhp_step *sp;
int cpu;
int ret;
+ lockdep_assert_cpus_held();
+
sp = cpuhp_get_step(state);
if (sp->multi_instance == false)
return -EINVAL;
- cpus_read_lock();
mutex_lock(&cpuhp_state_mutex);
if (!invoke || !sp->startup.multi)
@@ -1453,6 +1455,16 @@ add_node:
hlist_add_head(node, &sp->list);
unlock:
mutex_unlock(&cpuhp_state_mutex);
+ return ret;
+}
+
+int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
+ bool invoke)
+{
+ int ret;
+
+ cpus_read_lock();
+ ret = __cpuhp_state_add_instance_cpuslocked(state, node, invoke);
cpus_read_unlock();
return ret;
}
--
cgit v1.2.3
From fe5595c074005bd94f0c7d1644175941149f6768 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 24 May 2017 10:15:16 +0200
Subject: stop_machine: Provide stop_machine_cpuslocked()
Some call sites of stop_machine() are within a get_online_cpus() protected
region.
stop_machine() calls get_online_cpus() as well, which is possible in the
current implementation but prevents converting the hotplug locking to a
percpu rwsem.
Provide stop_machine_cpuslocked() to avoid nested calls to get_online_cpus().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081547.400700852@linutronix.de
---
include/linux/stop_machine.h | 26 +++++++++++++++++++++++---
kernel/stop_machine.c | 11 +++++++----
2 files changed, 30 insertions(+), 7 deletions(-)
(limited to 'include/linux')
diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h
index 3cc9632dcc2a..3d60275e3ba9 100644
--- a/include/linux/stop_machine.h
+++ b/include/linux/stop_machine.h
@@ -116,15 +116,29 @@ static inline int try_stop_cpus(const struct cpumask *cpumask,
* @fn() runs.
*
* This can be thought of as a very heavy write lock, equivalent to
- * grabbing every spinlock in the kernel. */
+ * grabbing every spinlock in the kernel.
+ *
+ * Protects against CPU hotplug.
+ */
int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
+/**
+ * stop_machine_cpuslocked: freeze the machine on all CPUs and run this function
+ * @fn: the function to run
+ * @data: the data ptr for the @fn()
+ * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
+ *
+ * Same as above. Must be called from with in a cpus_read_lock() protected
+ * region. Avoids nested calls to cpus_read_lock().
+ */
+int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
+
int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
const struct cpumask *cpus);
#else /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
-static inline int stop_machine(cpu_stop_fn_t fn, void *data,
- const struct cpumask *cpus)
+static inline int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data,
+ const struct cpumask *cpus)
{
unsigned long flags;
int ret;
@@ -134,6 +148,12 @@ static inline int stop_machine(cpu_stop_fn_t fn, void *data,
return ret;
}
+static inline int stop_machine(cpu_stop_fn_t fn, void *data,
+ const struct cpumask *cpus)
+{
+ return stop_machine_cpuslocked(fn, data, cpus);
+}
+
static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
const struct cpumask *cpus)
{
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 1eb82661ecdb..b7591261652d 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -552,7 +552,8 @@ static int __init cpu_stop_init(void)
}
early_initcall(cpu_stop_init);
-static int __stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus)
+int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data,
+ const struct cpumask *cpus)
{
struct multi_stop_data msdata = {
.fn = fn,
@@ -561,6 +562,8 @@ static int __stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cp
.active_cpus = cpus,
};
+ lockdep_assert_cpus_held();
+
if (!stop_machine_initialized) {
/*
* Handle the case where stop_machine() is called
@@ -590,9 +593,9 @@ int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus)
int ret;
/* No CPUs can come up or down during this. */
- get_online_cpus();
- ret = __stop_machine(fn, data, cpus);
- put_online_cpus();
+ cpus_read_lock();
+ ret = stop_machine_cpuslocked(fn, data, cpus);
+ cpus_read_unlock();
return ret;
}
EXPORT_SYMBOL_GPL(stop_machine);
--
cgit v1.2.3
From 9596695ee1e7eedd743c43811fe68299eb005b5c Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 24 May 2017 10:15:17 +0200
Subject: padata: Make padata_alloc() static
No users outside of padata.c
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-crypto@vger.kernel.org
Link: http://lkml.kernel.org/r/20170524081547.491457256@linutronix.de
---
include/linux/padata.h | 3 ---
kernel/padata.c | 32 ++++++++++++++++----------------
2 files changed, 16 insertions(+), 19 deletions(-)
(limited to 'include/linux')
diff --git a/include/linux/padata.h b/include/linux/padata.h
index 0f9e567d5e15..2f9c1f93b1ce 100644
--- a/include/linux/padata.h
+++ b/include/linux/padata.h
@@ -166,9 +166,6 @@ struct padata_instance {
extern struct padata_instance *padata_alloc_possible(
struct workqueue_struct *wq);
-extern struct padata_instance *padata_alloc(struct workqueue_struct *wq,
- const struct cpumask *pcpumask,
- const struct cpumask *cbcpumask);
extern void padata_free(struct padata_instance *pinst);
extern int padata_do_parallel(struct padata_instance *pinst,
struct padata_priv *padata, int cb_cpu);
diff --git a/kernel/padata.c b/kernel/padata.c
index ac8f1e524836..0c708f648853 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -933,19 +933,6 @@ static struct kobj_type padata_attr_type = {
.release = padata_sysfs_release,
};
-/**
- * padata_alloc_possible - Allocate and initialize padata instance.
- * Use the cpu_possible_mask for serial and
- * parallel workers.
- *
- * @wq: workqueue to use for the allocated padata instance
- */
-struct padata_instance *padata_alloc_possible(struct workqueue_struct *wq)
-{
- return padata_alloc(wq, cpu_possible_mask, cpu_possible_mask);
-}
-EXPORT_SYMBOL(padata_alloc_possible);
-
/**
* padata_alloc - allocate and initialize a padata instance and specify
* cpumasks for serial and parallel workers.
@@ -954,9 +941,9 @@ EXPORT_SYMBOL(padata_alloc_possible);
* @pcpumask: cpumask that will be used for padata parallelization
* @cbcpumask: cpumask that will be used for padata serialization
*/
-struct padata_instance *padata_alloc(struct workqueue_struct *wq,
- const struct cpumask *pcpumask,
- const struct cpumask *cbcpumask)
+static struct padata_instance *padata_alloc(struct workqueue_struct *wq,
+ const struct cpumask *pcpumask,
+ const struct cpumask *cbcpumask)
{
struct padata_instance *pinst;
struct parallel_data *pd = NULL;
@@ -1010,6 +997,19 @@ err:
return NULL;
}
+/**
+ * padata_alloc_possible - Allocate and initialize padata instance.
+ * Use the cpu_possible_mask for serial and
+ * parallel workers.
+ *
+ * @wq: workqueue to use for the allocated padata instance
+ */
+struct padata_instance *padata_alloc_possible(struct workqueue_struct *wq)
+{
+ return padata_alloc(wq, cpu_possible_mask, cpu_possible_mask);
+}
+EXPORT_SYMBOL(padata_alloc_possible);
+
/**
* padata_free - free a padata instance
*
--
cgit v1.2.3
From 0b2c2a71e6f07fb67e6f72817d39910f64d2e258 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 24 May 2017 10:15:32 +0200
Subject: PCI: Replace the racy recursion prevention
pci_call_probe() can called recursively when a physcial function is probed
and the probing creates virtual functions, which are populated via
pci_bus_add_device() which in turn can end up calling pci_call_probe()
again.
The code has an interesting way to prevent recursing into the workqueue
code. That's accomplished by a check whether the current task runs already
on the numa node which is associated with the device.
While that works to prevent the recursion into the workqueue code, it's
racy versus normal execution as there is no guarantee that the node does
not vanish after the check.
There is another issue with this code. It dereferences cpumask_of_node()
unconditionally without checking whether the node is available.
Make the detection reliable by:
- Mark a probed device as 'is_probed' in pci_call_probe()
- Check in pci_call_probe for a virtual function. If it's a virtual
function and the associated physical function device is marked
'is_probed' then this is a recursive call, so the call can be invoked in
the calling context.
- Add a check whether the node is online before dereferencing it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-pci@vger.kernel.org
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081548.771457199@linutronix.de
---
drivers/pci/pci-driver.c | 47 +++++++++++++++++++++++++----------------------
include/linux/pci.h | 1 +
2 files changed, 26 insertions(+), 22 deletions(-)
(limited to 'include/linux')
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 5bf92fd983e5..fe6be6382505 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -320,10 +320,19 @@ static long local_pci_probe(void *_ddi)
return 0;
}
+static bool pci_physfn_is_probed(struct pci_dev *dev)
+{
+#ifdef CONFIG_PCI_IOV
+ return dev->is_virtfn && dev->physfn->is_probed;
+#else
+ return false;
+#endif
+}
+
static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev,
const struct pci_device_id *id)
{
- int error, node;
+ int error, node, cpu;
struct drv_dev_and_id ddi = { drv, dev, id };
/*
@@ -332,33 +341,27 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev,
* on the right node.
*/
node = dev_to_node(&dev->dev);
+ dev->is_probed = 1;
+
+ cpu_hotplug_disable();
/*
- * On NUMA systems, we are likely to call a PF probe function using
- * work_on_cpu(). If that probe calls pci_enable_sriov() (which
- * adds the VF devices via pci_bus_add_device()), we may re-enter
- * this function to call the VF probe function. Calling
- * work_on_cpu() again will cause a lockdep warning. Since VFs are
- * always on the same node as the PF, we can work around this by
- * avoiding work_on_cpu() when we're already on the correct node.
- *
- * Preemption is enabled, so it's theoretically unsafe to use
- * numa_node_id(), but even if we run the probe function on the
- * wrong node, it should be functionally correct.
+ * Prevent nesting work_on_cpu() for the case where a Virtual Function
+ * device is probed from work_on_cpu() of the Physical device.
*/
- if (node >= 0 && node != numa_node_id()) {
- int cpu;
-
- cpu_hotplug_disable();
+ if (node < 0 || node >= MAX_NUMNODES || !node_online(node) ||
+ pci_physfn_is_probed(dev))
+ cpu = nr_cpu_ids;
+ else
cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask);
- if (cpu < nr_cpu_ids)
- error = work_on_cpu(cpu, local_pci_probe, &ddi);
- else
- error = local_pci_probe(&ddi);
- cpu_hotplug_enable();
- } else
+
+ if (cpu < nr_cpu_ids)
+ error = work_on_cpu(cpu, local_pci_probe, &ddi);
+ else
error = local_pci_probe(&ddi);
+ dev->is_probed = 0;
+ cpu_hotplug_enable();
return error;
}
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 33c2b0b77429..5026f2ae86db 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -371,6 +371,7 @@ struct pci_dev {
unsigned int irq_managed:1;
unsigned int has_secondary_link:1;
unsigned int non_compliant_bars:1; /* broken BARs; ignore them */
+ unsigned int is_probed:1; /* device probing in progress */
pci_dev_flags_t dev_flags;
atomic_t enable_cnt; /* pci_enable_device has been called */
--
cgit v1.2.3
From a63fbed776c7124ce9f606234267c3c095b2680e Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 24 May 2017 10:15:34 +0200
Subject: perf/tracing/cpuhotplug: Fix locking order
perf, tracing, kprobes and jump_labels have a gazillion of ways to create
dependency lock chains. Some of those involve nested invocations of
get_online_cpus().
The conversion of the hotplug locking to a percpu rwsem requires to avoid
such nested calls. sys_perf_event_open() protects most of the syscall logic
against cpu hotplug. This causes nested calls and lock inversions versus
ftrace and kprobes in various interesting ways.
It's impossible to move the hotplug locking to the outer end of all call
chains in the involved facilities, so the hotplug protection in
sys_perf_event_open() needs to be solved differently.
Introduce 'pmus_mutex' which protects a perf private online cpumask. This
mutex is taken when the mask is updated in the cpu hotplug callbacks and
can be taken in sys_perf_event_open() to protect the swhash setup/teardown
code and when the final judgement about a valid event has to be made.
[ tglx: Produced changelog and fixed the swhash interaction ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Link: http://lkml.kernel.org/r/20170524081548.930941109@linutronix.de
---
include/linux/perf_event.h | 2 +
kernel/events/core.c | 106 ++++++++++++++++++++++++++++++++-------------
2 files changed, 78 insertions(+), 30 deletions(-)
(limited to 'include/linux')
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 24a635887f28..7d6aa29094b2 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -801,6 +801,8 @@ struct perf_cpu_context {
struct list_head sched_cb_entry;
int sched_cb_usage;
+
+ int online;
};
struct perf_output_handle {
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 6e75a5c9412d..b97cda4d1777 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -389,6 +389,7 @@ static atomic_t nr_switch_events __read_mostly;
static LIST_HEAD(pmus);
static DEFINE_MUTEX(pmus_lock);
static struct srcu_struct pmus_srcu;
+static cpumask_var_t perf_online_mask;
/*
* perf event paranoia level:
@@ -3812,14 +3813,6 @@ find_get_context(struct pmu *pmu, struct task_struct *task,
if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
return ERR_PTR(-EACCES);
- /*
- * We could be clever and allow to attach a event to an
- * offline CPU and activate it when the CPU comes up, but
- * that's for later.
- */
- if (!cpu_online(cpu))
- return ERR_PTR(-ENODEV);
-
cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
ctx = &cpuctx->ctx;
get_ctx(ctx);
@@ -7703,7 +7696,8 @@ static int swevent_hlist_get_cpu(int cpu)
int err = 0;
mutex_lock(&swhash->hlist_mutex);
- if (!swevent_hlist_deref(swhash) && cpu_online(cpu)) {
+ if (!swevent_hlist_deref(swhash) &&
+ cpumask_test_cpu(cpu, perf_online_mask)) {
struct swevent_hlist *hlist;
hlist = kzalloc(sizeof(*hlist), GFP_KERNEL);
@@ -7724,7 +7718,7 @@ static int swevent_hlist_get(void)
{
int err, cpu, failed_cpu;
- get_online_cpus();
+ mutex_lock(&pmus_lock);
for_each_possible_cpu(cpu) {
err = swevent_hlist_get_cpu(cpu);
if (err) {
@@ -7732,8 +7726,7 @@ static int swevent_hlist_get(void)
goto fail;
}
}
- put_online_cpus();
-
+ mutex_unlock(&pmus_lock);
return 0;
fail:
for_each_possible_cpu(cpu) {
@@ -7741,8 +7734,7 @@ fail:
break;
swevent_hlist_put_cpu(cpu);
}
-
- put_online_cpus();
+ mutex_unlock(&pmus_lock);
return err;
}
@@ -8920,7 +8912,7 @@ perf_event_mux_interval_ms_store(struct device *dev,
pmu->hrtimer_interval_ms = timer;
/* update all cpuctx for this PMU */
- get_online_cpus();
+ cpus_read_lock();
for_each_online_cpu(cpu) {
struct perf_cpu_context *cpuctx;
cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
@@ -8929,7 +8921,7 @@ perf_event_mux_interval_ms_store(struct device *dev,
cpu_function_call(cpu,
(remote_function_f)perf_mux_hrtimer_restart, cpuctx);
}
- put_online_cpus();
+ cpus_read_unlock();
mutex_unlock(&mux_interval_mutex);
return count;
@@ -9059,6 +9051,7 @@ skip_type:
lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex);
lockdep_set_class(&cpuctx->ctx.lock, &cpuctx_lock);
cpuctx->ctx.pmu = pmu;
+ cpuctx->online = cpumask_test_cpu(cpu, perf_online_mask);
__perf_mux_hrtimer_init(cpuctx, cpu);
}
@@ -9882,12 +9875,10 @@ SYSCALL_DEFINE5(perf_event_open,
goto err_task;
}
- get_online_cpus();
-
if (task) {
err = mutex_lock_interruptible(&task->signal->cred_guard_mutex);
if (err)
- goto err_cpus;
+ goto err_cred;
/*
* Reuse ptrace permission checks for now.
@@ -10073,6 +10064,23 @@ SYSCALL_DEFINE5(perf_event_open,
goto err_locked;
}
+ if (!task) {
+ /*
+ * Check if the @cpu we're creating an event for is online.
+ *
+ * We use the perf_cpu_context::ctx::mutex to serialize against
+ * the hotplug notifiers. See perf_event_{init,exit}_cpu().
+ */
+ struct perf_cpu_context *cpuctx =
+ container_of(ctx, struct perf_cpu_context, ctx);
+
+ if (!cpuctx->online) {
+ err = -ENODEV;
+ goto err_locked;
+ }
+ }
+
+
/*
* Must be under the same ctx::mutex as perf_install_in_context(),
* because we need to serialize with concurrent event creation.
@@ -10162,8 +10170,6 @@ SYSCALL_DEFINE5(perf_event_open,
put_task_struct(task);
}
- put_online_cpus();
-
mutex_lock(¤t->perf_event_mutex);
list_add_tail(&event->owner_entry, ¤t->perf_event_list);
mutex_unlock(¤t->perf_event_mutex);
@@ -10197,8 +10203,6 @@ err_alloc:
err_cred:
if (task)
mutex_unlock(&task->signal->cred_guard_mutex);
-err_cpus:
- put_online_cpus();
err_task:
if (task)
put_task_struct(task);
@@ -10253,6 +10257,21 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
goto err_unlock;
}
+ if (!task) {
+ /*
+ * Check if the @cpu we're creating an event for is online.
+ *
+ * We use the perf_cpu_context::ctx::mutex to serialize against
+ * the hotplug notifiers. See perf_event_{init,exit}_cpu().
+ */
+ struct perf_cpu_context *cpuctx =
+ container_of(ctx, struct perf_cpu_context, ctx);
+ if (!cpuctx->online) {
+ err = -ENODEV;
+ goto err_unlock;
+ }
+ }
+
if (!exclusive_event_installable(event, ctx)) {
err = -EBUSY;
goto err_unlock;
@@ -10920,6 +10939,8 @@ static void __init perf_event_init_all_cpus(void)
struct swevent_htable *swhash;
int cpu;
+ zalloc_cpumask_var(&perf_online_mask, GFP_KERNEL);
+
for_each_possible_cpu(cpu) {
swhash = &per_cpu(swevent_htable, cpu);
mutex_init(&swhash->hlist_mutex);
@@ -10935,7 +10956,7 @@ static void __init perf_event_init_all_cpus(void)
}
}
-int perf_event_init_cpu(unsigned int cpu)
+void perf_swevent_init_cpu(unsigned int cpu)
{
struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
@@ -10948,7 +10969,6 @@ int perf_event_init_cpu(unsigned int cpu)
rcu_assign_pointer(swhash->swevent_hlist, hlist);
}
mutex_unlock(&swhash->hlist_mutex);
- return 0;
}
#if defined CONFIG_HOTPLUG_CPU || defined CONFIG_KEXEC_CORE
@@ -10966,19 +10986,22 @@ static void __perf_event_exit_context(void *__info)
static void perf_event_exit_cpu_context(int cpu)
{
+ struct perf_cpu_context *cpuctx;
struct perf_event_context *ctx;
struct pmu *pmu;
- int idx;
- idx = srcu_read_lock(&pmus_srcu);
- list_for_each_entry_rcu(pmu, &pmus, entry) {
- ctx = &per_cpu_ptr(pmu->pmu_cpu_context, cpu)->ctx;
+ mutex_lock(&pmus_lock);
+ list_for_each_entry(pmu, &pmus, entry) {
+ cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+ ctx = &cpuctx->ctx;
mutex_lock(&ctx->mutex);
smp_call_function_single(cpu, __perf_event_exit_context, ctx, 1);
+ cpuctx->online = 0;
mutex_unlock(&ctx->mutex);
}
- srcu_read_unlock(&pmus_srcu, idx);
+ cpumask_clear_cpu(cpu, perf_online_mask);
+ mutex_unlock(&pmus_lock);
}
#else
@@ -10986,6 +11009,29 @@ static void perf_event_exit_cpu_context(int cpu) { }
#endif
+int perf_event_init_cpu(unsigned int cpu)
+{
+ struct perf_cpu_context *cpuctx;
+ struct perf_event_context *ctx;
+ struct pmu *pmu;
+
+ perf_swevent_init_cpu(cpu);
+
+ mutex_lock(&pmus_lock);
+ cpumask_set_cpu(cpu, perf_online_mask);
+ list_for_each_entry(pmu, &pmus, entry) {
+ cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+ ctx = &cpuctx->ctx;
+
+ mutex_lock(&ctx->mutex);
+ cpuctx->online = 1;
+ mutex_unlock(&ctx->mutex);
+ }
+ mutex_unlock(&pmus_lock);
+
+ return 0;
+}
+
int perf_event_exit_cpu(unsigned int cpu)
{
perf_event_exit_cpu_context(cpu);
--
cgit v1.2.3
From fc8dffd379ca5620664336eb895a426b42847558 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 24 May 2017 10:15:40 +0200
Subject: cpu/hotplug: Convert hotplug locking to percpu rwsem
There are no more (known) nested calls to get_online_cpus() and all
observed lock ordering problems have been addressed.
Replace the magic nested 'rwsem' hackery with a percpu-rwsem.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081549.447014063@linutronix.de
---
include/linux/cpu.h | 2 +-
kernel/cpu.c | 107 +++++++---------------------------------------------
2 files changed, 14 insertions(+), 95 deletions(-)
(limited to 'include/linux')
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index af4d660798e5..ca73bc1563f4 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -103,7 +103,7 @@ extern void cpus_write_lock(void);
extern void cpus_write_unlock(void);
extern void cpus_read_lock(void);
extern void cpus_read_unlock(void);
-static inline void lockdep_assert_cpus_held(void) { }
+extern void lockdep_assert_cpus_held(void);
extern void cpu_hotplug_disable(void);
extern void cpu_hotplug_enable(void);
void clear_tasks_mm_cpumask(int cpu);
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 142d889d9f69..66836216ebae 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -27,6 +27,7 @@
#include <linux/smpboot.h>
#include <linux/relay.h>
#include <linux/slab.h>
+#include <linux/percpu-rwsem.h>
#include <trace/events/power.h>
#define CREATE_TRACE_POINTS
@@ -196,121 +197,41 @@ void cpu_maps_update_done(void)
mutex_unlock(&cpu_add_remove_lock);
}
-/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
+/*
+ * If set, cpu_up and cpu_down will return -EBUSY and do nothing.
* Should always be manipulated under cpu_add_remove_lock
*/
static int cpu_hotplug_disabled;
#ifdef CONFIG_HOTPLUG_CPU
-static struct {
- struct task_struct *active_writer;
- /* wait queue to wake up the active_writer */
- wait_queue_head_t wq;
- /* verifies that no writer will get active while readers are active */
- struct mutex lock;
- /*
- * Also blocks the new readers during
- * an ongoing cpu hotplug operation.
- */
- atomic_t refcount;
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
- struct lockdep_map dep_map;
-#endif
-} cpu_hotplug = {
- .active_writer = NULL,
- .wq = __WAIT_QUEUE_HEAD_INITIALIZER(cpu_hotplug.wq),
- .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
- .dep_map = STATIC_LOCKDEP_MAP_INIT("cpu_hotplug.dep_map", &cpu_hotplug.dep_map),
-#endif
-};
-
-/* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */
-#define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map)
-#define cpuhp_lock_acquire_tryread() \
- lock_map_acquire_tryread(&cpu_hotplug.dep_map)
-#define cpuhp_lock_acquire() lock_map_acquire(&cpu_hotplug.dep_map)
-#define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map)
-
+DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock);
void cpus_read_lock(void)
{
- might_sleep();
- if (cpu_hotplug.active_writer == current)
- return;
- cpuhp_lock_acquire_read();
- mutex_lock(&cpu_hotplug.lock);
- atomic_inc(&cpu_hotplug.refcount);
- mutex_unlock(&cpu_hotplug.lock);
+ percpu_down_read(&cpu_hotplug_lock);
}
EXPORT_SYMBOL_GPL(cpus_read_lock);
void cpus_read_unlock(void)
{
- int refcount;
-
- if (cpu_hotplug.active_writer == current)
- return;
-
- refcount = atomic_dec_return(&cpu_hotplug.refcount);
- if (WARN_ON(refcount < 0)) /* try to fix things up */
- atomic_inc(&cpu_hotplug.refcount);
-
- if (refcount <= 0 && waitqueue_active(&cpu_hotplug.wq))
- wake_up(&cpu_hotplug.wq);
-
- cpuhp_lock_release();
-
+ percpu_up_read(&cpu_hotplug_lock);
}
EXPORT_SYMBOL_GPL(cpus_read_unlock);
-/*
- * This ensures that the hotplug operation can begin only when the
- * refcount goes to zero.
- *
- * Note that during a cpu-hotplug operation, the new readers, if any,
- * will be blocked by the cpu_hotplug.lock
- *
- * Since cpu_hotplug_begin() is always called after invoking
- * cpu_maps_update_begin(), we can be sure that only one writer is active.
- *
- * Note that theoretically, there is a possibility of a livelock:
- * - Refcount goes to zero, last reader wakes up the sleeping
- * writer.
- * - Last reader unlocks the cpu_hotplug.lock.
- * - A new reader arrives at this moment, bumps up the refcount.
- * - The writer acquires the cpu_hotplug.lock finds the refcount
- * non zero and goes to sleep again.
- *
- * However, this is very difficult to achieve in practice since
- * get_online_cpus() not an api which is called all that often.
- *
- */
void cpus_write_lock(void)
{
- DEFINE_WAIT(wait);
-
- cpu_hotplug.active_writer = current;
- cpuhp_lock_acquire();
-
- for (;;) {
- mutex_lock(&cpu_hotplug.lock);
- prepare_to_wait(&cpu_hotplug.wq, &wait, TASK_UNINTERRUPTIBLE);
- if (likely(!atomic_read(&cpu_hotplug.refcount)))
- break;
- mutex_unlock(&cpu_hotplug.lock);
- schedule();
- }
- finish_wait(&cpu_hotplug.wq, &wait);
+ percpu_down_write(&cpu_hotplug_lock);
}
void cpus_write_unlock(void)
{
- cpu_hotplug.active_writer = NULL;
- mutex_unlock(&cpu_hotplug.lock);
- cpuhp_lock_release();
+ percpu_up_write(&cpu_hotplug_lock);
+}
+
+void lockdep_assert_cpus_held(void)
+{
+ percpu_rwsem_assert_held(&cpu_hotplug_lock);
}
/*
@@ -344,8 +265,6 @@ void cpu_hotplug_enable(void)
EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
#endif /* CONFIG_HOTPLUG_CPU */
-/* Notifier wrappers for transitioning to state machine */
-
static int bringup_wait_for_ap(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
--
cgit v1.2.3
From 62ec05dd71b19f5be890a1992227cc7b2ac0adc4 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 24 May 2017 10:15:41 +0200
Subject: sched: Provide is_percpu_thread() helper
Provide a helper function for checking whether current task is a per cpu
thread.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081549.541649540@linutronix.de
---
include/linux/sched.h | 10 ++++++++++
1 file changed, 10 insertions(+)
(limited to 'include/linux')
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 2b69fc650201..3dfa5f99d6ee 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1265,6 +1265,16 @@ extern struct pid *cad_pid;
#define tsk_used_math(p) ((p)->flags & PF_USED_MATH)
#define used_math() tsk_used_math(current)
+static inline bool is_percpu_thread(void)
+{
+#ifdef CONFIG_SMP
+ return (current->flags & PF_NO_SETAFFINITY) &&
+ (current->nr_cpus_allowed == 1);
+#else
+ return true;
+#endif
+}
+
/* Per-process atomic flags. */
#define PFA_NO_NEW_PRIVS 0 /* May not gain new privileges. */
#define PFA_SPREAD_PAGE 1 /* Spread page cache over cpuset */
--
cgit v1.2.3