[PATCH v2 05/12] locking/mutex: Expose mutex_owner()

John Stultz
2023-03-20T23:37:59Z

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

Implementing proxy execution requires that scheduler code be able to
identify the current owner of a mutex. Expose a new helper
mutex_owner() for this purpose.

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>
Cc: kernel-team@android.com
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
[Removed the EXPORT_SYMBOL]
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Connor O'Brien <connoro@google.com>
[jstultz: Tweaked subject line]
Signed-off-by: John Stultz <jstultz@google.com>
---
include/linux/mutex.h | 2 ++
kernel/locking/mutex.c | 5 +++++
2 files changed, 7 insertions(+)

diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index 8f226d460f51..ebdc59cb0bf6 100644
--- a/include/linux/mutex.h
+++ b/include/linux/mutex.h
@@ -118,6 +118,8 @@ do { \
extern void __mutex_init(struct mutex *lock, const char *name,
struct lock_class_key *key);

+extern struct task_struct *mutex_owner(struct mutex *lock);
+
/**
* mutex_is_locked - is the mutex locked
* @lock: the mutex to be queried
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index d322f7c1c8fa..ead4213232cc 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -81,6 +81,11 @@ static inline struct task_struct *__mutex_owner(struct mutex *lock)
return (struct task_struct *)(atomic_long_read(&lock->owner) & ~MUTEX_FLAGS);
}

+struct task_struct *mutex_owner(struct mutex *lock)
+{
+ return __mutex_owner(lock);
+}
+
static inline struct task_struct *__owner_task(unsigned long owner)
{
return (struct task_struct *)(owner & ~MUTEX_FLAGS);
--
2.40.0.rc1.284.g88254d51c5-goog