[tip: locking/core] locking: Apply contention tracepoints in the slow path

From: tip-bot2 for Namhyung Kim
Date: Tue Apr 05 2022 - 07:23:43 EST

Next message: Greg Kroah-Hartman: "[PATCH 5.16 0122/1017] dm integrity: set journal entry unused when shrinking device"
Previous message: Greg Kroah-Hartman: "[PATCH 5.16 0112/1017] drm/simpledrm: Add "panel orientation" property on non-upright mounted LCD panels"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

The following commit has been merged into the locking/core branch of tip:

Commit-ID: ee042be16cb455116d0fe99b77c6bc8baf87c8c6
Gitweb: https://git.kernel.org/tip/ee042be16cb455116d0fe99b77c6bc8baf87c8c6
Author: Namhyung Kim <namhyung@xxxxxxxxxx>
AuthorDate: Tue, 22 Mar 2022 11:57:09 -07:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Tue, 05 Apr 2022 10:24:35 +02:00

locking: Apply contention tracepoints in the slow path

Adding the lock contention tracepoints in various lock function slow
paths. Note that each arch can define spinlock differently, I only
added it only to the generic qspinlock for now.

Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Tested-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
Link: https://lkml.kernel.org/r/20220322185709.141236-3-namhyung@xxxxxxxxxx
---
kernel/locking/mutex.c | 3 +++
kernel/locking/percpu-rwsem.c | 5 +++++
kernel/locking/qrwlock.c | 9 +++++++++
kernel/locking/qspinlock.c | 5 +++++
kernel/locking/rtmutex.c | 11 +++++++++++
kernel/locking/rwbase_rt.c | 7 +++++++
kernel/locking/rwsem.c | 9 +++++++++
kernel/locking/semaphore.c | 15 ++++++++++++++-
8 files changed, 63 insertions(+), 1 deletion(-)

diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index ee2fd76..c88deda 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -644,6 +644,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
}

set_current_state(state);
+ trace_contention_begin(lock, 0);
for (;;) {
bool first;

@@ -710,6 +711,7 @@ acquired:
skip_wait:
/* got the lock - cleanup and rejoice! */
lock_acquired(&lock->dep_map, ip);
+ trace_contention_end(lock, 0);

if (ww_ctx)
ww_mutex_lock_acquired(ww, ww_ctx);
@@ -721,6 +723,7 @@ skip_wait:
err:
__set_current_state(TASK_RUNNING);
__mutex_remove_waiter(lock, &waiter);
+ trace_contention_end(lock, ret);
err_early_kill:
raw_spin_unlock(&lock->wait_lock);
debug_mutex_free_waiter(&waiter);
diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c
index c9fdae9..5fe4c54 100644
--- a/kernel/locking/percpu-rwsem.c
+++ b/kernel/locking/percpu-rwsem.c
@@ -9,6 +9,7 @@
#include <linux/sched/task.h>
#include <linux/sched/debug.h>
#include <linux/errno.h>
+#include <trace/events/lock.h>

int __percpu_init_rwsem(struct percpu_rw_semaphore *sem,
const char *name, struct lock_class_key *key)
@@ -171,9 +172,11 @@ bool __sched __percpu_down_read(struct percpu_rw_semaphore *sem, bool try)
if (try)
return false;

+ trace_contention_begin(sem, LCB_F_PERCPU | LCB_F_READ);
preempt_enable();
percpu_rwsem_wait(sem, /* .reader = */ true);
preempt_disable();
+ trace_contention_end(sem, 0);

return true;
}
@@ -216,6 +219,7 @@ void __sched percpu_down_write(struct percpu_rw_semaphore *sem)
{
might_sleep();
rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
+ trace_contention_begin(sem, LCB_F_PERCPU | LCB_F_WRITE);

/* Notify readers to take the slow path. */
rcu_sync_enter(&sem->rss);
@@ -237,6 +241,7 @@ void __sched percpu_down_write(struct percpu_rw_semaphore *sem)

/* Wait for all active readers to complete. */
rcuwait_wait_event(&sem->writer, readers_active_check(sem), TASK_UNINTERRUPTIBLE);
+ trace_contention_end(sem, 0);
}
EXPORT_SYMBOL_GPL(percpu_down_write);

diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c
index ec36b73..7f42e52 100644
--- a/kernel/locking/qrwlock.c
+++ b/kernel/locking/qrwlock.c
@@ -12,6 +12,7 @@
#include <linux/percpu.h>
#include <linux/hardirq.h>
#include <linux/spinlock.h>
+#include <trace/events/lock.h>

/**
* queued_read_lock_slowpath - acquire read lock of a queue rwlock
@@ -34,6 +35,8 @@ void queued_read_lock_slowpath(struct qrwlock *lock)
}
atomic_sub(_QR_BIAS, &lock->cnts);

+ trace_contention_begin(lock, LCB_F_SPIN | LCB_F_READ);
+
/*
* Put the reader into the wait queue
*/
@@ -51,6 +54,8 @@ void queued_read_lock_slowpath(struct qrwlock *lock)
* Signal the next one in queue to become queue head
*/
arch_spin_unlock(&lock->wait_lock);
+
+ trace_contention_end(lock, 0);
}
EXPORT_SYMBOL(queued_read_lock_slowpath);

@@ -62,6 +67,8 @@ void queued_write_lock_slowpath(struct qrwlock *lock)
{
int cnts;

+ trace_contention_begin(lock, LCB_F_SPIN | LCB_F_WRITE);
+
/* Put the writer into the wait queue */
arch_spin_lock(&lock->wait_lock);

@@ -79,5 +86,7 @@ void queued_write_lock_slowpath(struct qrwlock *lock)
} while (!atomic_try_cmpxchg_acquire(&lock->cnts, &cnts, _QW_LOCKED));
unlock:
arch_spin_unlock(&lock->wait_lock);
+
+ trace_contention_end(lock, 0);
}
EXPORT_SYMBOL(queued_write_lock_slowpath);
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index cbff6ba..65a9a10 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -22,6 +22,7 @@
#include <linux/prefetch.h>
#include <asm/byteorder.h>
#include <asm/qspinlock.h>
+#include <trace/events/lock.h>

/*
* Include queued spinlock statistics code
@@ -401,6 +402,8 @@ pv_queue:
idx = node->count++;
tail = encode_tail(smp_processor_id(), idx);

+ trace_contention_begin(lock, LCB_F_SPIN);
+
/*
* 4 nodes are allocated based on the assumption that there will
* not be nested NMIs taking spinlocks. That may not be true in
@@ -554,6 +557,8 @@ locked:
pv_kick_node(lock, next);

release:
+ trace_contention_end(lock, 0);
+
/*
* release the node
*/
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 8555c4e..7779ee8 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -24,6 +24,8 @@
#include <linux/sched/wake_q.h>
#include <linux/ww_mutex.h>

+#include <trace/events/lock.h>
+
#include "rtmutex_common.h"

#ifndef WW_RT
@@ -1579,6 +1581,8 @@ static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock,

set_current_state(state);

+ trace_contention_begin(lock, LCB_F_RT);
+
ret = task_blocks_on_rt_mutex(lock, waiter, current, ww_ctx, chwalk);
if (likely(!ret))
ret = rt_mutex_slowlock_block(lock, ww_ctx, state, NULL, waiter);
@@ -1601,6 +1605,9 @@ static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock,
* unconditionally. We might have to fix that up.
*/
fixup_rt_mutex_waiters(lock);
+
+ trace_contention_end(lock, ret);
+
return ret;
}

@@ -1683,6 +1690,8 @@ static void __sched rtlock_slowlock_locked(struct rt_mutex_base *lock)
/* Save current state and set state to TASK_RTLOCK_WAIT */
current_save_and_set_rtlock_wait_state();

+ trace_contention_begin(lock, LCB_F_RT);
+
task_blocks_on_rt_mutex(lock, &waiter, current, NULL, RT_MUTEX_MIN_CHAINWALK);

for (;;) {
@@ -1712,6 +1721,8 @@ static void __sched rtlock_slowlock_locked(struct rt_mutex_base *lock)
*/
fixup_rt_mutex_waiters(lock);
debug_rt_mutex_free_waiter(&waiter);
+
+ trace_contention_end(lock, 0);
}

static __always_inline void __sched rtlock_slowlock(struct rt_mutex_base *lock)
diff --git a/kernel/locking/rwbase_rt.c b/kernel/locking/rwbase_rt.c
index 6fd3162..c201aad 100644
--- a/kernel/locking/rwbase_rt.c
+++ b/kernel/locking/rwbase_rt.c
@@ -112,6 +112,8 @@ static int __sched __rwbase_read_lock(struct rwbase_rt *rwb,
* Reader2 to call up_read(), which might be unbound.
*/

+ trace_contention_begin(rwb, LCB_F_RT | LCB_F_READ);
+
/*
* For rwlocks this returns 0 unconditionally, so the below
* !ret conditionals are optimized out.
@@ -130,6 +132,8 @@ static int __sched __rwbase_read_lock(struct rwbase_rt *rwb,
raw_spin_unlock_irq(&rtm->wait_lock);
if (!ret)
rwbase_rtmutex_unlock(rtm);
+
+ trace_contention_end(rwb, ret);
return ret;
}

@@ -247,11 +251,13 @@ static int __sched rwbase_write_lock(struct rwbase_rt *rwb,
goto out_unlock;

rwbase_set_and_save_current_state(state);
+ trace_contention_begin(rwb, LCB_F_RT | LCB_F_WRITE);
for (;;) {
/* Optimized out for rwlocks */
if (rwbase_signal_pending_state(state, current)) {
rwbase_restore_current_state();
__rwbase_write_unlock(rwb, 0, flags);
+ trace_contention_end(rwb, -EINTR);
return -EINTR;
}

@@ -265,6 +271,7 @@ static int __sched rwbase_write_lock(struct rwbase_rt *rwb,
set_current_state(state);
}
rwbase_restore_current_state();
+ trace_contention_end(rwb, 0);

out_unlock:
raw_spin_unlock_irqrestore(&rtm->wait_lock, flags);
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 16b532b..9d1db4a 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -27,6 +27,7 @@
#include <linux/export.h>
#include <linux/rwsem.h>
#include <linux/atomic.h>
+#include <trace/events/lock.h>

#ifndef CONFIG_PREEMPT_RT
#include "lock_events.h"
@@ -1056,6 +1057,8 @@ queue:
if (!wake_q_empty(&wake_q))
wake_up_q(&wake_q);

+ trace_contention_begin(sem, LCB_F_READ);
+
/* wait to be given the lock */
for (;;) {
set_current_state(state);
@@ -1077,12 +1080,14 @@ queue:

__set_current_state(TASK_RUNNING);
lockevent_inc(rwsem_rlock);
+ trace_contention_end(sem, 0);
return sem;

out_nolock:
rwsem_del_wake_waiter(sem, &waiter, &wake_q);
__set_current_state(TASK_RUNNING);
lockevent_inc(rwsem_rlock_fail);
+ trace_contention_end(sem, -EINTR);
return ERR_PTR(-EINTR);
}

@@ -1132,6 +1137,8 @@ rwsem_down_write_slowpath(struct rw_semaphore *sem, int state)

/* wait until we successfully acquire the lock */
set_current_state(state);
+ trace_contention_begin(sem, LCB_F_WRITE);
+
for (;;) {
if (rwsem_try_write_lock(sem, &waiter)) {
/* rwsem_try_write_lock() implies ACQUIRE on success */
@@ -1171,6 +1178,7 @@ trylock_again:
__set_current_state(TASK_RUNNING);
raw_spin_unlock_irq(&sem->wait_lock);
lockevent_inc(rwsem_wlock);
+ trace_contention_end(sem, 0);
return sem;

out_nolock:
@@ -1178,6 +1186,7 @@ out_nolock:
raw_spin_lock_irq(&sem->wait_lock);
rwsem_del_wake_waiter(sem, &waiter, &wake_q);
lockevent_inc(rwsem_wlock_fail);
+ trace_contention_end(sem, -EINTR);
return ERR_PTR(-EINTR);
}

diff --git a/kernel/locking/semaphore.c b/kernel/locking/semaphore.c
index 9ee381e..f2654d2 100644
--- a/kernel/locking/semaphore.c
+++ b/kernel/locking/semaphore.c
@@ -32,6 +32,7 @@
#include <linux/semaphore.h>
#include <linux/spinlock.h>
#include <linux/ftrace.h>
+#include <trace/events/lock.h>

static noinline void __down(struct semaphore *sem);
static noinline int __down_interruptible(struct semaphore *sem);
@@ -205,7 +206,7 @@ struct semaphore_waiter {
* constant, and thus optimised away by the compiler. Likewise the
* 'timeout' parameter for the cases without timeouts.
*/
-static inline int __sched __down_common(struct semaphore *sem, long state,
+static inline int __sched ___down_common(struct semaphore *sem, long state,
long timeout)
{
struct semaphore_waiter waiter;
@@ -236,6 +237,18 @@ static inline int __sched __down_common(struct semaphore *sem, long state,
return -EINTR;
}

+static inline int __sched __down_common(struct semaphore *sem, long state,
+ long timeout)
+{
+ int ret;
+
+ trace_contention_begin(sem, 0);
+ ret = ___down_common(sem, state, timeout);
+ trace_contention_end(sem, ret);
+
+ return ret;
+}
+
static noinline void __sched __down(struct semaphore *sem)
{
__down_common(sem, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);

Next message: Greg Kroah-Hartman: "[PATCH 5.16 0122/1017] dm integrity: set journal entry unused when shrinking device"
Previous message: Greg Kroah-Hartman: "[PATCH 5.16 0112/1017] drm/simpledrm: Add "panel orientation" property on non-upright mounted LCD panels"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]