[PATCH v3 02/14] locking/mutex: make mutex::wait_lock irq safe

John Stultz
2023-04-11T04:25:34Z

From: Juri Lelli <juri.lelli@redhat.com>

mutex::wait_lock might be nested under rq->lock.

Make it irq safe then.

Cc: Joel Fernandes <joelaf@google.com>
Cc: Qais Yousef <qyousef@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Zimuzo Ezeozue <zezeozue@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[rebase & fix {un,}lock_wait_lock helpers in ww_mutex.h]
Signed-off-by: Connor O'Brien <connoro@google.com>
Signed-off-by: John Stultz <jstultz@google.com>
---
v3:
* Re-added this patch after it was dropped in v2 which
caused lockdep warnings to trip.
---
kernel/locking/mutex.c | 18 ++++++++++--------
kernel/locking/ww_mutex.h | 22 ++++++++++++----------
2 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 1582756914df..a528e7f42caa 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -572,6 +572,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
{
struct mutex_waiter waiter;
struct ww_mutex *ww;
+ unsigned long flags;
int ret;

if (!use_ww_ctx)
@@ -614,7 +615,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
return 0;
}

- raw_spin_lock(&lock->wait_lock);
+ raw_spin_lock_irqsave(&lock->wait_lock, flags);
/*
* After waiting to acquire the wait_lock, try again.
*/
@@ -675,7 +676,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
goto err;
}

- raw_spin_unlock(&lock->wait_lock);
+ raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
if (ww_ctx)
ww_ctx_wake(ww_ctx);
schedule_preempt_disabled();
@@ -698,9 +699,9 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
trace_contention_begin(lock, LCB_F_MUTEX);
}

- raw_spin_lock(&lock->wait_lock);
+ raw_spin_lock_irqsave(&lock->wait_lock, flags);
}
- raw_spin_lock(&lock->wait_lock);
+ raw_spin_lock_irqsave(&lock->wait_lock, flags);
acquired:
__set_current_state(TASK_RUNNING);

@@ -726,7 +727,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
if (ww_ctx)
ww_mutex_lock_acquired(ww, ww_ctx);

- raw_spin_unlock(&lock->wait_lock);
+ raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
if (ww_ctx)
ww_ctx_wake(ww_ctx);
preempt_enable();
@@ -737,7 +738,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
__mutex_remove_waiter(lock, &waiter);
err_early_kill:
trace_contention_end(lock, ret);
- raw_spin_unlock(&lock->wait_lock);
+ raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
debug_mutex_free_waiter(&waiter);
mutex_release(&lock->dep_map, ip);
if (ww_ctx)
@@ -909,6 +910,7 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne
struct task_struct *next = NULL;
DEFINE_WAKE_Q(wake_q);
unsigned long owner;
+ unsigned long flags;

mutex_release(&lock->dep_map, ip);

@@ -935,7 +937,7 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne
}
}

- raw_spin_lock(&lock->wait_lock);
+ raw_spin_lock_irqsave(&lock->wait_lock, flags);
debug_mutex_unlock(lock);
if (!list_empty(&lock->wait_list)) {
/* get the first entry from the wait-list: */
@@ -953,7 +955,7 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne
__mutex_handoff(lock, next);

preempt_disable();
- raw_spin_unlock(&lock->wait_lock);
+ raw_spin_unlock_irqrestore(&lock->wait_lock, flags);

wake_up_q(&wake_q);
preempt_enable();
diff --git a/kernel/locking/ww_mutex.h b/kernel/locking/ww_mutex.h
index e49ea5336473..984a4e0bff36 100644
--- a/kernel/locking/ww_mutex.h
+++ b/kernel/locking/ww_mutex.h
@@ -70,14 +70,14 @@ __ww_mutex_has_waiters(struct mutex *lock)
return atomic_long_read(&lock->owner) & MUTEX_FLAG_WAITERS;
}

-static inline void lock_wait_lock(struct mutex *lock)
+static inline void lock_wait_lock(struct mutex *lock, unsigned long *flags)
{
- raw_spin_lock(&lock->wait_lock);
+ raw_spin_lock_irqsave(&lock->wait_lock, *flags);
}

-static inline void unlock_wait_lock(struct mutex *lock)
+static inline void unlock_wait_lock(struct mutex *lock, unsigned long flags)
{
- raw_spin_unlock(&lock->wait_lock);
+ raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
}

static inline void lockdep_assert_wait_lock_held(struct mutex *lock)
@@ -144,14 +144,14 @@ __ww_mutex_has_waiters(struct rt_mutex *lock)
return rt_mutex_has_waiters(&lock->rtmutex);
}

-static inline void lock_wait_lock(struct rt_mutex *lock)
+static inline void lock_wait_lock(struct rt_mutex *lock, unsigned long *flags)
{
- raw_spin_lock(&lock->rtmutex.wait_lock);
+ raw_spin_lock_irqsave(&lock->rtmutex.wait_lock, *flags);
}

-static inline void unlock_wait_lock(struct rt_mutex *lock)
+static inline void unlock_wait_lock(struct rt_mutex *lock, flags)
{
- raw_spin_unlock(&lock->rtmutex.wait_lock);
+ raw_spin_unlock_irqrestore(&lock->rtmutex.wait_lock, flags);
}

static inline void lockdep_assert_wait_lock_held(struct rt_mutex *lock)
@@ -383,6 +383,8 @@ __ww_mutex_check_waiters(struct MUTEX *lock, struct ww_acquire_ctx *ww_ctx)
static __always_inline void
ww_mutex_set_context_fastpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
{
+ unsigned long flags;
+
ww_mutex_lock_acquired(lock, ctx);

/*
@@ -410,9 +412,9 @@ ww_mutex_set_context_fastpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
* Uh oh, we raced in fastpath, check if any of the waiters need to
* die or wound us.
*/
- lock_wait_lock(&lock->base);
+ lock_wait_lock(&lock->base, &flags);
__ww_mutex_check_waiters(&lock->base, ctx);
- unlock_wait_lock(&lock->base);
+ unlock_wait_lock(&lock->base, flags);
}

static __always_inline int
--
2.40.0.577.gac1e443424-goog