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Message-ID: <20250308155623.959825668@linutronix.de>
Date: Sat, 8 Mar 2025 17:48:30 +0100 (CET)
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Anna-Maria Behnsen <anna-maria@...utronix.de>,
Frederic Weisbecker <frederic@...nel.org>,
Benjamin Segall <bsegall@...gle.com>,
Eric Dumazet <edumazet@...gle.com>,
Andrey Vagin <avagin@...nvz.org>,
Pavel Tikhomirov <ptikhomirov@...tuozzo.com>,
Peter Zijlstra <peterz@...radead.org>,
Cyrill Gorcunov <gorcunov@...il.com>
Subject: [patch V3 08/18] posix-timers: Simplify lock/unlock_timer()
Since the integration of sigqueue into the timer struct, lock_timer() is
only used in task context. So taking the lock with irqsave() is not longer
required.
Convert it to use spin_[un]lock_irq().
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Frederic Weisbecker <frederic@...nel.org>
---
V2: New patch
---
kernel/time/posix-timers.c | 70 ++++++++++++++++++---------------------------
1 file changed, 29 insertions(+), 41 deletions(-)
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -53,14 +53,19 @@ static const struct k_clock clock_realti
#error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"
#endif
-static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags);
+static struct k_itimer *__lock_timer(timer_t timer_id);
-#define lock_timer(tid, flags) \
-({ struct k_itimer *__timr; \
- __cond_lock(&__timr->it_lock, __timr = __lock_timer(tid, flags)); \
- __timr; \
+#define lock_timer(tid) \
+({ struct k_itimer *__timr; \
+ __cond_lock(&__timr->it_lock, __timr = __lock_timer(tid)); \
+ __timr; \
})
+static inline void unlock_timer(struct k_itimer *timr)
+{
+ spin_unlock_irq(&timr->it_lock);
+}
+
static int hash(struct signal_struct *sig, unsigned int nr)
{
return hash_32(hash32_ptr(sig) ^ nr, HASH_BITS(posix_timers_hashtable));
@@ -144,11 +149,6 @@ static int posix_timer_add(struct k_itim
return -EAGAIN;
}
-static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
-{
- spin_unlock_irqrestore(&timr->it_lock, flags);
-}
-
static int posix_get_realtime_timespec(clockid_t which_clock, struct timespec64 *tp)
{
ktime_get_real_ts64(tp);
@@ -538,7 +538,7 @@ COMPAT_SYSCALL_DEFINE3(timer_create, clo
}
#endif
-static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags)
+static struct k_itimer *__lock_timer(timer_t timer_id)
{
struct k_itimer *timr;
@@ -580,14 +580,14 @@ static struct k_itimer *__lock_timer(tim
guard(rcu)();
timr = posix_timer_by_id(timer_id);
if (timr) {
- spin_lock_irqsave(&timr->it_lock, *flags);
+ spin_lock_irq(&timr->it_lock);
/*
* Validate under timr::it_lock that timr::it_signal is
* still valid. Pairs with #1 above.
*/
if (timr->it_signal == current->signal)
return timr;
- spin_unlock_irqrestore(&timr->it_lock, *flags);
+ spin_unlock_irq(&timr->it_lock);
}
return NULL;
}
@@ -680,17 +680,16 @@ void common_timer_get(struct k_itimer *t
static int do_timer_gettime(timer_t timer_id, struct itimerspec64 *setting)
{
struct k_itimer *timr;
- unsigned long flags;
int ret = 0;
- timr = lock_timer(timer_id, &flags);
+ timr = lock_timer(timer_id);
if (!timr)
return -EINVAL;
memset(setting, 0, sizeof(*setting));
timr->kclock->timer_get(timr, setting);
- unlock_timer(timr, flags);
+ unlock_timer(timr);
return ret;
}
@@ -746,15 +745,14 @@ SYSCALL_DEFINE2(timer_gettime32, timer_t
SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
{
struct k_itimer *timr;
- unsigned long flags;
int overrun;
- timr = lock_timer(timer_id, &flags);
+ timr = lock_timer(timer_id);
if (!timr)
return -EINVAL;
overrun = timer_overrun_to_int(timr);
- unlock_timer(timr, flags);
+ unlock_timer(timr);
return overrun;
}
@@ -813,14 +811,13 @@ static void common_timer_wait_running(st
* when the task which tries to delete or disarm the timer has preempted
* the task which runs the expiry in task work context.
*/
-static struct k_itimer *timer_wait_running(struct k_itimer *timer,
- unsigned long *flags)
+static struct k_itimer *timer_wait_running(struct k_itimer *timer)
{
timer_t timer_id = READ_ONCE(timer->it_id);
/* Prevent kfree(timer) after dropping the lock */
scoped_guard (rcu) {
- unlock_timer(timer, *flags);
+ unlock_timer(timer);
/*
* kc->timer_wait_running() might drop RCU lock. So @timer
* cannot be touched anymore after the function returns!
@@ -829,7 +826,7 @@ static struct k_itimer *timer_wait_runni
}
/* Relock the timer. It might be not longer hashed. */
- return lock_timer(timer_id, flags);
+ return lock_timer(timer_id);
}
/*
@@ -889,7 +886,6 @@ static int do_timer_settime(timer_t time
struct itimerspec64 *old_spec64)
{
struct k_itimer *timr;
- unsigned long flags;
int error;
if (!timespec64_valid(&new_spec64->it_interval) ||
@@ -899,7 +895,7 @@ static int do_timer_settime(timer_t time
if (old_spec64)
memset(old_spec64, 0, sizeof(*old_spec64));
- timr = lock_timer(timer_id, &flags);
+ timr = lock_timer(timer_id);
retry:
if (!timr)
return -EINVAL;
@@ -916,10 +912,10 @@ static int do_timer_settime(timer_t time
// We already got the old time...
old_spec64 = NULL;
/* Unlocks and relocks the timer if it still exists */
- timr = timer_wait_running(timr, &flags);
+ timr = timer_wait_running(timr);
goto retry;
}
- unlock_timer(timr, flags);
+ unlock_timer(timr);
return error;
}
@@ -995,10 +991,7 @@ static inline void posix_timer_cleanup_i
/* Delete a POSIX.1b interval timer. */
SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
{
- struct k_itimer *timer;
- unsigned long flags;
-
- timer = lock_timer(timer_id, &flags);
+ struct k_itimer *timer = lock_timer(timer_id);
retry_delete:
if (!timer)
@@ -1009,7 +1002,7 @@ SYSCALL_DEFINE1(timer_delete, timer_t, t
if (unlikely(timer->kclock->timer_del(timer) == TIMER_RETRY)) {
/* Unlocks and relocks the timer if it still exists */
- timer = timer_wait_running(timer, &flags);
+ timer = timer_wait_running(timer);
goto retry_delete;
}
@@ -1028,7 +1021,7 @@ SYSCALL_DEFINE1(timer_delete, timer_t, t
WRITE_ONCE(timer->it_signal, NULL);
}
- unlock_timer(timer, flags);
+ unlock_timer(timer);
posix_timer_unhash_and_free(timer);
return 0;
}
@@ -1039,12 +1032,7 @@ SYSCALL_DEFINE1(timer_delete, timer_t, t
*/
static void itimer_delete(struct k_itimer *timer)
{
- unsigned long flags;
-
- /*
- * irqsave is required to make timer_wait_running() work.
- */
- spin_lock_irqsave(&timer->it_lock, flags);
+ spin_lock_irq(&timer->it_lock);
retry_delete:
/*
@@ -1065,7 +1053,7 @@ static void itimer_delete(struct k_itime
* do_exit() only for the last thread of the thread group.
* So no other task can access and delete that timer.
*/
- if (WARN_ON_ONCE(timer_wait_running(timer, &flags) != timer))
+ if (WARN_ON_ONCE(timer_wait_running(timer) != timer))
return;
goto retry_delete;
@@ -1082,7 +1070,7 @@ static void itimer_delete(struct k_itime
*/
WRITE_ONCE(timer->it_signal, NULL);
- spin_unlock_irqrestore(&timer->it_lock, flags);
+ spin_unlock_irq(&timer->it_lock);
posix_timer_unhash_and_free(timer);
}
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