Dear RT Folks,
This is the RT stable review cycle of patch 4.19.312-rt134-rc2.
Please scream at me if I messed something up. Please test the patches
too.
The -rc release is also available on kernel.org
https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git
on the v4.19-rt-next branch.
If all goes well, this patch will be converted to the next main
release on 2024-05-13.
Signing key fingerprint:
5BF6 7BC5 0826 72CA BB45 ACAE 587C 5ECA 5D0A 306C
All keys used for the above files and repositories can be found on the
following git repository:
git://git.kernel.org/pub/scm/docs/kernel/pgpkeys.git
Enjoy!
Daniel
Changes from v4.19.307-rt133:
Daniel Wagner (1):
Linux 4.19.312-rt134
localversion-rt | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--
2.44.0
v4.19.312-rt134-rc2 stable review patch.
If anyone has any objections, please let me know.
-----------
Signed-off-by: Daniel Wagner <[email protected]>
---
localversion-rt | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/localversion-rt b/localversion-rt
index c2c7e0fb6685..6067da4c8c99 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt133
+-rt134
--
2.44.0
Hi Sebastian,
On 06.05.24 12:46, Daniel Wagner wrote:
> Dear RT Folks,
>
> This is the RT stable review cycle of patch 4.19.312-rt134-rc2.
>
> Please scream at me if I messed something up. Please test the patches
> too.
My announce script is not attaching any conflict resolve diffs
(eventually, I'll fix this). Could have a look if I got the
kernel/time/timer.c upddate right? This was caused by stable
including the 030dcdd197d7 ("timers: Prepare support for
PREEMPT_RT") patch.
commit 2c1a32c5e05fd75885186793bc0d26e0a65b473d
Merge: 4790d0210f19 3d86e7f5bdf3
Author: Daniel Wagner <[email protected]>
Date: Wed Apr 17 16:31:21 2024 +0200
Merge tag 'v4.19.312' into v4.19-rt-next
This is the 4.19.312 stable release
Conflicts:
include/linux/timer.h
kernel/time/timer.c
diff --git a/include/linux/timer.h b/include/linux/timer.h
remerge CONFLICT (content): Merge conflict in include/linux/timer.h
index b70c5168a346..aef40cac2add 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -173,13 +173,6 @@ extern void add_timer(struct timer_list *timer);
extern int try_to_del_timer_sync(struct timer_list *timer);
extern int timer_delete_sync(struct timer_list *timer);
-<<<<<<< 4790d0210f19 (Linux 4.19.307-rt133)
-#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT_FULL)
- extern int del_timer_sync(struct timer_list *timer);
-#else
-# define del_timer_sync(t) del_timer(t)
-#endif
-=======
/**
* del_timer_sync - Delete a pending timer and wait for a running callback
* @timer: The timer to be deleted
@@ -192,7 +185,6 @@ static inline int del_timer_sync(struct timer_list
*timer)
{
return timer_delete_sync(timer);
}
->>>>>>> 3d86e7f5bdf3 (Linux 4.19.312)
#define del_singleshot_timer_sync(t) del_timer_sync(t)
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
remerge CONFLICT (content): Merge conflict in kernel/time/timer.c
index 911191916df1..bc5ce0cf9488 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1250,6 +1250,25 @@ int del_timer(struct timer_list *timer)
}
EXPORT_SYMBOL(del_timer);
+static int __try_to_del_timer_sync(struct timer_list *timer,
+ struct timer_base **basep)
+{
+ struct timer_base *base;
+ unsigned long flags;
+ int ret = -1;
+
+ debug_assert_init(timer);
+
+ *basep = base = lock_timer_base(timer, &flags);
+
+ if (base->running_timer != timer)
+ ret = detach_if_pending(timer, base, true);
+
+ raw_spin_unlock_irqrestore(&base->lock, flags);
+
+ return ret;
+}
+
/**
* try_to_del_timer_sync - Try to deactivate a timer
* @timer: Timer to deactivate
@@ -1269,19 +1288,8 @@ EXPORT_SYMBOL(del_timer);
int try_to_del_timer_sync(struct timer_list *timer)
{
struct timer_base *base;
- unsigned long flags;
- int ret = -1;
-
- debug_assert_init(timer);
-
- base = lock_timer_base(timer, &flags);
-
- if (base->running_timer != timer)
- ret = detach_if_pending(timer, base, true);
-
- raw_spin_unlock_irqrestore(&base->lock, flags);
- return ret;
+ return __try_to_del_timer_sync(timer, &base);
}
EXPORT_SYMBOL(try_to_del_timer_sync);
@@ -1303,7 +1311,6 @@ static inline void timer_base_unlock_expiry(struct
timer_base *base)
/*
* The counterpart to del_timer_wait_running().
-<<<<<<< 4790d0210f19 (Linux 4.19.307-rt133)
*
* If there is a waiter for base->expiry_lock, then it was waiting for the
* timer callback to finish. Drop expiry_lock and reaquire it. That allows
@@ -1359,64 +1366,35 @@ static inline void
timer_sync_wait_running(struct timer_base *base) { }
static inline void del_timer_wait_running(struct timer_list *timer) { }
#endif
-#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT_FULL)
-/**
- * del_timer_sync - deactivate a timer and wait for the handler to finish.
- * @timer: the timer to be deactivated
-=======
->>>>>>> 3d86e7f5bdf3 (Linux 4.19.312)
- *
- * If there is a waiter for base->expiry_lock, then it was waiting for the
- * timer callback to finish. Drop expiry_lock and reaquire it. That allows
- * the waiter to acquire the lock and make progress.
- */
-static void timer_sync_wait_running(struct timer_base *base)
+static int __del_timer_sync(struct timer_list *timer)
{
- if (atomic_read(&base->timer_waiters)) {
- spin_unlock(&base->expiry_lock);
- spin_lock(&base->expiry_lock);
- }
-}
+ struct timer_base *base;
+ int ret;
-/*
- * This function is called on PREEMPT_RT kernels when the fast path
- * deletion of a timer failed because the timer callback function was
- * running.
- *
- * This prevents priority inversion, if the softirq thread on a remote CPU
- * got preempted, and it prevents a life lock when the task which tries to
- * delete a timer preempted the softirq thread running the timer callback
- * function.
- */
-static void del_timer_wait_running(struct timer_list *timer)
-{
- u32 tf;
+ /*
+ * Must be able to sleep on PREEMPT_RT because of the slowpath in
+ * del_timer_wait_running().
+ */
+#if 0
+ if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(timer->flags & TIMER_IRQSAFE))
+ lockdep_assert_preemption_enabled();
+#endif
- tf = READ_ONCE(timer->flags);
- if (!(tf & TIMER_MIGRATING)) {
- struct timer_base *base = get_timer_base(tf);
+ for (;;) {
+ ret = __try_to_del_timer_sync(timer, &base);
+ if (ret >= 0)
+ return ret;
+
+ if (READ_ONCE(timer->flags) & TIMER_IRQSAFE)
+ continue;
/*
- * Mark the base as contended and grab the expiry lock,
- * which is held by the softirq across the timer
- * callback. Drop the lock immediately so the softirq can
- * expire the next timer. In theory the timer could already
- * be running again, but that's more than unlikely and just
- * causes another wait loop.
+ * When accessing the lock, timers of base are no longer expired
+ * and so timer is no longer running.
*/
- atomic_inc(&base->timer_waiters);
- spin_lock_bh(&base->expiry_lock);
- atomic_dec(&base->timer_waiters);
- spin_unlock_bh(&base->expiry_lock);
+ timer_sync_wait_running(base);
}
}
-#else
-static inline void timer_base_init_expiry_lock(struct timer_base *base) { }
-static inline void timer_base_lock_expiry(struct timer_base *base) { }
-static inline void timer_base_unlock_expiry(struct timer_base *base) { }
-static inline void timer_sync_wait_running(struct timer_base *base) { }
-static inline void del_timer_wait_running(struct timer_list *timer) { }
-#endif
/**
* timer_delete_sync - Deactivate a timer and wait for the handler to
finish.
@@ -1459,8 +1437,6 @@ static inline void del_timer_wait_running(struct
timer_list *timer) { }
*/
int timer_delete_sync(struct timer_list *timer)
{
- int ret;
-
#ifdef CONFIG_LOCKDEP
unsigned long flags;
@@ -1478,43 +1454,14 @@ int timer_delete_sync(struct timer_list *timer)
* could lead to deadlock.
*/
WARN_ON(in_irq() && !(timer->flags & TIMER_IRQSAFE));
-<<<<<<< 4790d0210f19 (Linux 4.19.307-rt133)
-
/*
* Must be able to sleep on PREEMPT_RT because of the slowpath in
- * del_timer_wait_running().
+ * __del_timer_sync().
*/
-#if 0
if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(timer->flags & TIMER_IRQSAFE))
- lockdep_assert_preemption_enabled();
-#endif
-
- do {
- ret = try_to_del_timer_sync(timer);
+ might_sleep();
- if (unlikely(ret < 0)) {
- del_timer_wait_running(timer);
- cpu_relax();
- }
- } while (ret < 0);
-
- return ret;
-}
-EXPORT_SYMBOL(del_timer_sync);
-#endif
-=======
->>>>>>> 3d86e7f5bdf3 (Linux 4.19.312)
-
- do {
- ret = try_to_del_timer_sync(timer);
-
- if (unlikely(ret < 0)) {
- del_timer_wait_running(timer);
- cpu_relax();
- }
- } while (ret < 0);
-
- return ret;
+ return __del_timer_sync(timer);
}
EXPORT_SYMBOL(timer_delete_sync);
@@ -1585,14 +1532,11 @@ static void expire_timers(struct timer_base
*base, struct hlist_head *head)
if (timer->flags & TIMER_IRQSAFE) {
raw_spin_unlock(&base->lock);
call_timer_fn(timer, fn, baseclk);
- base->running_timer = NULL;
raw_spin_lock(&base->lock);
base->running_timer = NULL;
} else {
raw_spin_unlock_irq(&base->lock);
call_timer_fn(timer, fn, baseclk);
- base->running_timer = NULL;
- timer_sync_wait_running(base);
raw_spin_lock_irq(&base->lock);
base->running_timer = NULL;
timer_sync_wait_running(base);
On 2024-05-06 13:00:39 [+0200], Daniel Wagner wrote:
> Hi Sebastian,
Hi Daniel,
> On 06.05.24 12:46, Daniel Wagner wrote:
> > Dear RT Folks,
> >
> > This is the RT stable review cycle of patch 4.19.312-rt134-rc2.
> >
> > Please scream at me if I messed something up. Please test the patches
> > too.
>
> My announce script is not attaching any conflict resolve diffs
> (eventually, I'll fix this). Could have a look if I got the
> kernel/time/timer.c upddate right? This was caused by stable
> including the 030dcdd197d7 ("timers: Prepare support for
> PREEMPT_RT") patch.
I compared mine outcome vs v4.19-rt-next and the diff at the bottom came
out:
- timer_delete_sync() used to have "#if 0" block around
lockdep_assert_preemption_enabled() because the function is not part
of v4.19. You ended up with might_sleep() which is a minor change.
Your queue as of a previous release had the if0 block (in
__del_timer_sync()).
I would say this is minor but looks like a miss-merge. Therefore I
would say it should go back for consistency vs previous release and
not change it due to conflicts.
- The timer_delete_sync() is structured differently with
__del_timer_sync(). That function invokes timer_sync_wait_running()
which drops two locks which are not acquired. That is wrong. It should
have been del_timer_wait_running().
I suggest you apply the diff below to align it with later versions. It
also gets rid of the basep argument in __try_to_del_timer_sync() which
is not really used.
As an alternative I can send you my rebased queue if this makes it
easier for you.
Sebastian
------------------>8-----------------
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1250,25 +1250,6 @@ int del_timer(struct timer_list *timer)
}
EXPORT_SYMBOL(del_timer);
-static int __try_to_del_timer_sync(struct timer_list *timer,
- struct timer_base **basep)
-{
- struct timer_base *base;
- unsigned long flags;
- int ret = -1;
-
- debug_assert_init(timer);
-
- *basep = base = lock_timer_base(timer, &flags);
-
- if (base->running_timer != timer)
- ret = detach_if_pending(timer, base, true);
-
- raw_spin_unlock_irqrestore(&base->lock, flags);
-
- return ret;
-}
-
/**
* try_to_del_timer_sync - Try to deactivate a timer
* @timer: Timer to deactivate
@@ -1288,8 +1269,19 @@ static int __try_to_del_timer_sync(struct timer_list *timer,
int try_to_del_timer_sync(struct timer_list *timer)
{
struct timer_base *base;
+ unsigned long flags;
+ int ret = -1;
- return __try_to_del_timer_sync(timer, &base);
+ debug_assert_init(timer);
+
+ base = lock_timer_base(timer, &flags);
+
+ if (base->running_timer != timer)
+ ret = detach_if_pending(timer, base, true);
+
+ raw_spin_unlock_irqrestore(&base->lock, flags);
+
+ return ret;
}
EXPORT_SYMBOL(try_to_del_timer_sync);
@@ -1366,36 +1358,6 @@ static inline void timer_sync_wait_running(struct timer_base *base) { }
static inline void del_timer_wait_running(struct timer_list *timer) { }
#endif
-static int __del_timer_sync(struct timer_list *timer)
-{
- struct timer_base *base;
- int ret;
-
- /*
- * Must be able to sleep on PREEMPT_RT because of the slowpath in
- * del_timer_wait_running().
- */
-#if 0
- if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(timer->flags & TIMER_IRQSAFE))
- lockdep_assert_preemption_enabled();
-#endif
-
- for (;;) {
- ret = __try_to_del_timer_sync(timer, &base);
- if (ret >= 0)
- return ret;
-
- if (READ_ONCE(timer->flags) & TIMER_IRQSAFE)
- continue;
-
- /*
- * When accessing the lock, timers of base are no longer expired
- * and so timer is no longer running.
- */
- timer_sync_wait_running(base);
- }
-}
-
/**
* timer_delete_sync - Deactivate a timer and wait for the handler to finish.
* @timer: The timer to be deactivated
@@ -1437,6 +1399,8 @@ static int __del_timer_sync(struct timer_list *timer)
*/
int timer_delete_sync(struct timer_list *timer)
{
+ int ret;
+
#ifdef CONFIG_LOCKDEP
unsigned long flags;
@@ -1454,14 +1418,26 @@ int timer_delete_sync(struct timer_list *timer)
* could lead to deadlock.
*/
WARN_ON(in_irq() && !(timer->flags & TIMER_IRQSAFE));
+
/*
* Must be able to sleep on PREEMPT_RT because of the slowpath in
- * __del_timer_sync().
+ * del_timer_wait_running().
*/
+#if 0
if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(timer->flags & TIMER_IRQSAFE))
- might_sleep();
+ lockdep_assert_preemption_enabled();
+#endif
- return __del_timer_sync(timer);
+ do {
+ ret = try_to_del_timer_sync(timer);
+
+ if (unlikely(ret < 0)) {
+ del_timer_wait_running(timer);
+ cpu_relax();
+ }
+ } while (ret < 0);
+
+ return ret;
}
EXPORT_SYMBOL(timer_delete_sync);
Hi Sebastian,
On Tue, May 07, 2024 at 11:54:07AM GMT, Sebastian Andrzej Siewior wrote:
> I compared mine outcome vs v4.19-rt-next and the diff at the bottom came
> out:
>
> - timer_delete_sync() used to have "#if 0" block around
> lockdep_assert_preemption_enabled() because the function is not part
> of v4.19. You ended up with might_sleep() which is a minor change.
> Your queue as of a previous release had the if0 block (in
> __del_timer_sync()).
> I would say this is minor but looks like a miss-merge. Therefore I
> would say it should go back for consistency vs previous release and
> not change it due to conflicts.
Makes sense.
> - The timer_delete_sync() is structured differently with
> __del_timer_sync(). That function invokes timer_sync_wait_running()
> which drops two locks which are not acquired. That is wrong. It should
> have been del_timer_wait_running().
Understood. I was a bit strungling here. Glad you caught this error.
> I suggest you apply the diff below to align it with later versions. It
> also gets rid of the basep argument in __try_to_del_timer_sync() which
> is not really used.
Will do.
> As an alternative I can send you my rebased queue if this makes it
> easier for you.
Yes please, this makes it easy to sync the rebase branch.
Thanks a lot!
Cheers,
Daniel