[PATCH v7 03/23] locking/mutex: Make mutex::wait_lock irq safe

John Stultz
2023-12-20T00:19:09Z

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: Youssef Esmat <youssefesmat@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>
Cc: Metin Kaya <Metin.Kaya@arm.com>
Cc: Xuewen Yan <xuewen.yan94@gmail.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-team@android.com
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.
v7:
* Fix function definition for PREEMPT_RT case, as pointed out
by Metin Kaya.
* Fix incorrect flags handling in PREEMPT_RT case as found by
Metin Kaya
---
kernel/locking/mutex.c | 18 ++++++++++--------
kernel/locking/ww_mutex.h | 22 +++++++++++-----------
2 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 8337ed0dbf81..73d98dd23eec 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -573,6 +573,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
DEFINE_WAKE_Q(wake_q);
struct mutex_waiter waiter;
struct ww_mutex *ww;
+ unsigned long flags;
int ret;

if (!use_ww_ctx)
@@ -615,7 +616,7 @@ __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.
*/
@@ -676,7 +677,7 @@ __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);
/* Make sure we do wakeups before calling schedule */
if (!wake_q_empty(&wake_q)) {
wake_up_q(&wake_q);
@@ -702,9 +703,9 @@ __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);

@@ -730,7 +731,7 @@ __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);
wake_up_q(&wake_q);
preempt_enable();
return 0;
@@ -740,7 +741,7 @@ __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);
wake_up_q(&wake_q);
@@ -911,6 +912,7 @@ 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);

@@ -938,7 +940,7 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne
}

preempt_disable();
- 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: */
@@ -955,7 +957,7 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne
if (owner & MUTEX_FLAG_HANDOFF)
__mutex_handoff(lock, next);

- 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 7189c6631d90..9facc0ddfdd3 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, unsigned long *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)
@@ -380,6 +380,7 @@ static __always_inline void
ww_mutex_set_context_fastpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
{
DEFINE_WAKE_Q(wake_q);
+ unsigned long flags;

ww_mutex_lock_acquired(lock, ctx);

@@ -408,10 +409,9 @@ 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, &wake_q);
- unlock_wait_lock(&lock->base);
-
+ unlock_wait_lock(&lock->base, &flags);
wake_up_q(&wake_q);
}

--
2.43.0.472.g3155946c3a-goog