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Date: Sun, 03 Sep 2023 00:33:19 +0200
From: Michał Mirosław <mirq-linux@...e.qmqm.pl>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>
Cc: Waiman Long <longman@...hat.com>,
Boqun Feng <boqun.feng@...il.com>, linux-kernel@...r.kernel.org
Subject: [PATCH v2] locking/mutex: remove redundant argument from
__mutex_lock_common()
use_ww_ctx is equivalent to ww_ctx != NULL. The one case where
use_ww_ctx was true but ww_ctx == NULL leads to the same
__mutex_add_waiter() call via __ww_mutex_add_waiter().
Since now __ww_mutex_add_waiter() is called only with ww_ctx != NULL
(from both regular and PREEMPT_RT implementations), remove the
branch there.
Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
---
v2: extended commit message to note that PREEMPT_RT does not call
__ww_mutex_add_waiter() with ww_ctx == NULL
---
kernel/locking/mutex.c | 16 ++++++----------
kernel/locking/ww_mutex.h | 5 -----
2 files changed, 6 insertions(+), 15 deletions(-)
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index d973fe6041bf..2f0e318233f5 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -568,15 +568,12 @@ EXPORT_SYMBOL(ww_mutex_unlock);
static __always_inline int __sched
__mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclass,
struct lockdep_map *nest_lock, unsigned long ip,
- struct ww_acquire_ctx *ww_ctx, const bool use_ww_ctx)
+ struct ww_acquire_ctx *ww_ctx)
{
struct mutex_waiter waiter;
struct ww_mutex *ww;
int ret;
- if (!use_ww_ctx)
- ww_ctx = NULL;
-
might_sleep();
MUTEX_WARN_ON(lock->magic != lock);
@@ -627,12 +624,11 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
debug_mutex_lock_common(lock, &waiter);
waiter.task = current;
- if (use_ww_ctx)
- waiter.ww_ctx = ww_ctx;
+ waiter.ww_ctx = ww_ctx;
lock_contended(&lock->dep_map, ip);
- if (!use_ww_ctx) {
+ if (!ww_ctx) {
/* add waiting tasks to the end of the waitqueue (FIFO): */
__mutex_add_waiter(lock, &waiter, &lock->wait_list);
} else {
@@ -744,14 +740,14 @@ static int __sched
__mutex_lock(struct mutex *lock, unsigned int state, unsigned int subclass,
struct lockdep_map *nest_lock, unsigned long ip)
{
- return __mutex_lock_common(lock, state, subclass, nest_lock, ip, NULL, false);
+ return __mutex_lock_common(lock, state, subclass, nest_lock, ip, NULL);
}
static int __sched
__ww_mutex_lock(struct mutex *lock, unsigned int state, unsigned int subclass,
unsigned long ip, struct ww_acquire_ctx *ww_ctx)
{
- return __mutex_lock_common(lock, state, subclass, NULL, ip, ww_ctx, true);
+ return __mutex_lock_common(lock, state, subclass, NULL, ip, ww_ctx);
}
/**
@@ -831,7 +827,7 @@ mutex_lock_io_nested(struct mutex *lock, unsigned int subclass)
token = io_schedule_prepare();
__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,
- subclass, NULL, _RET_IP_, NULL, 0);
+ subclass, NULL, _RET_IP_, NULL);
io_schedule_finish(token);
}
EXPORT_SYMBOL_GPL(mutex_lock_io_nested);
diff --git a/kernel/locking/ww_mutex.h b/kernel/locking/ww_mutex.h
index 3ad2cc4823e5..11acb2efe976 100644
--- a/kernel/locking/ww_mutex.h
+++ b/kernel/locking/ww_mutex.h
@@ -493,11 +493,6 @@ __ww_mutex_add_waiter(struct MUTEX_WAITER *waiter,
struct MUTEX_WAITER *cur, *pos = NULL;
bool is_wait_die;
- if (!ww_ctx) {
- __ww_waiter_add(lock, waiter, NULL);
- return 0;
- }
-
is_wait_die = ww_ctx->is_wait_die;
/*
--
2.39.2
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