* [PATCH] wait: don't wake up freezable wait by freezing fake signal
@ 2023-08-22 7:45 ` Ming Qian
0 siblings, 0 replies; 6+ messages in thread
From: Ming Qian @ 2023-08-22 7:45 UTC (permalink / raw)
To: mingo, peterz, juri.lelli, vincent.guittot
Cc: dietmar.eggemann, rostedt, bsegall, mgorman, bristot, vschneid,
eagle.zhou, tao.jiang_2, linux-imx, linux-kernel,
linux-arm-kernel
kernel may try to wake up task with fake signal when freezing task,
if the task is waiting event using wait_event_freezable,
it's better to freeze the wait, instead of breaking it.
otherwise the caller may need to retry the wait,
maybe like below code:
if (rc == -ERESTARTSYS && freezing(current)) {
clear_thread_flag(TIF_SIGPENDING);
goto again;
}
Signed-off-by: TaoJiang <tao.jiang_2@nxp.com>
Signed-off-by: Ming Qian <ming.qian@nxp.com>
---
include/linux/wait.h | 9 +++++++--
kernel/sched/wait.c | 14 ++++++++++++++
2 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/include/linux/wait.h b/include/linux/wait.h
index 5ec7739400f4..975ee67f259a 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -287,6 +287,7 @@ static inline void wake_up_pollfree(struct wait_queue_head *wq_head)
(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
extern void init_wait_entry(struct wait_queue_entry *wq_entry, int flags);
+bool freezing_wait(struct wait_queue_entry *wq_entry, int state);
/*
* The below macro ___wait_event() has an explicit shadow of the __ret
@@ -314,8 +315,12 @@ extern void init_wait_entry(struct wait_queue_entry *wq_entry, int flags);
break; \
\
if (___wait_is_interruptible(state) && __int) { \
- __ret = __int; \
- goto __out; \
+ if (unlikely(freezing_wait(&__wq_entry, state))) { \
+ clear_thread_flag(TIF_SIGPENDING); \
+ } else { \
+ __ret = __int; \
+ goto __out; \
+ } \
} \
\
cmd; \
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 802d98cf2de3..37c3b2bc1fc9 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -5,6 +5,8 @@
* (C) 2004 Nadia Yvette Chambers, Oracle
*/
+#include <linux/freezer.h>
+
void __init_waitqueue_head(struct wait_queue_head *wq_head, const char *name, struct lock_class_key *key)
{
spin_lock_init(&wq_head->lock);
@@ -484,3 +486,15 @@ int woken_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int sy
return default_wake_function(wq_entry, mode, sync, key);
}
EXPORT_SYMBOL(woken_wake_function);
+
+bool freezing_wait(struct wait_queue_entry *wq_entry, int state)
+{
+ if (!(state & TASK_FREEZABLE))
+ return false;
+ if (fatal_signal_pending(wq_entry->private))
+ return false;
+ if (unlikely(freezing(wq_entry->private)))
+ return true;
+ return false;
+}
+EXPORT_SYMBOL(freezing_wait);
--
2.38.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH] wait: don't wake up freezable wait by freezing fake signal
@ 2023-08-22 7:45 ` Ming Qian
0 siblings, 0 replies; 6+ messages in thread
From: Ming Qian @ 2023-08-22 7:45 UTC (permalink / raw)
To: mingo, peterz, juri.lelli, vincent.guittot
Cc: dietmar.eggemann, rostedt, bsegall, mgorman, bristot, vschneid,
eagle.zhou, tao.jiang_2, linux-imx, linux-kernel,
linux-arm-kernel
kernel may try to wake up task with fake signal when freezing task,
if the task is waiting event using wait_event_freezable,
it's better to freeze the wait, instead of breaking it.
otherwise the caller may need to retry the wait,
maybe like below code:
if (rc == -ERESTARTSYS && freezing(current)) {
clear_thread_flag(TIF_SIGPENDING);
goto again;
}
Signed-off-by: TaoJiang <tao.jiang_2@nxp.com>
Signed-off-by: Ming Qian <ming.qian@nxp.com>
---
include/linux/wait.h | 9 +++++++--
kernel/sched/wait.c | 14 ++++++++++++++
2 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/include/linux/wait.h b/include/linux/wait.h
index 5ec7739400f4..975ee67f259a 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -287,6 +287,7 @@ static inline void wake_up_pollfree(struct wait_queue_head *wq_head)
(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
extern void init_wait_entry(struct wait_queue_entry *wq_entry, int flags);
+bool freezing_wait(struct wait_queue_entry *wq_entry, int state);
/*
* The below macro ___wait_event() has an explicit shadow of the __ret
@@ -314,8 +315,12 @@ extern void init_wait_entry(struct wait_queue_entry *wq_entry, int flags);
break; \
\
if (___wait_is_interruptible(state) && __int) { \
- __ret = __int; \
- goto __out; \
+ if (unlikely(freezing_wait(&__wq_entry, state))) { \
+ clear_thread_flag(TIF_SIGPENDING); \
+ } else { \
+ __ret = __int; \
+ goto __out; \
+ } \
} \
\
cmd; \
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 802d98cf2de3..37c3b2bc1fc9 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -5,6 +5,8 @@
* (C) 2004 Nadia Yvette Chambers, Oracle
*/
+#include <linux/freezer.h>
+
void __init_waitqueue_head(struct wait_queue_head *wq_head, const char *name, struct lock_class_key *key)
{
spin_lock_init(&wq_head->lock);
@@ -484,3 +486,15 @@ int woken_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int sy
return default_wake_function(wq_entry, mode, sync, key);
}
EXPORT_SYMBOL(woken_wake_function);
+
+bool freezing_wait(struct wait_queue_entry *wq_entry, int state)
+{
+ if (!(state & TASK_FREEZABLE))
+ return false;
+ if (fatal_signal_pending(wq_entry->private))
+ return false;
+ if (unlikely(freezing(wq_entry->private)))
+ return true;
+ return false;
+}
+EXPORT_SYMBOL(freezing_wait);
--
2.38.1
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] wait: don't wake up freezable wait by freezing fake signal
2023-08-22 7:45 ` Ming Qian
@ 2023-09-25 10:08 ` Peter Zijlstra
-1 siblings, 0 replies; 6+ messages in thread
From: Peter Zijlstra @ 2023-09-25 10:08 UTC (permalink / raw)
To: Ming Qian
Cc: mingo, juri.lelli, vincent.guittot, dietmar.eggemann, rostedt,
bsegall, mgorman, bristot, vschneid, eagle.zhou, tao.jiang_2,
linux-imx, linux-kernel, linux-arm-kernel
On Tue, Aug 22, 2023 at 03:45:47PM +0800, Ming Qian wrote:
> kernel may try to wake up task with fake signal when freezing task,
> if the task is waiting event using wait_event_freezable,
> it's better to freeze the wait, instead of breaking it.
>
> otherwise the caller may need to retry the wait,
> maybe like below code:
>
> if (rc == -ERESTARTSYS && freezing(current)) {
> clear_thread_flag(TIF_SIGPENDING);
> goto again;
> }
I'm not sure I get it -- is there an actual problem, or are you trying
to optimize something?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] wait: don't wake up freezable wait by freezing fake signal
@ 2023-09-25 10:08 ` Peter Zijlstra
0 siblings, 0 replies; 6+ messages in thread
From: Peter Zijlstra @ 2023-09-25 10:08 UTC (permalink / raw)
To: Ming Qian
Cc: mingo, juri.lelli, vincent.guittot, dietmar.eggemann, rostedt,
bsegall, mgorman, bristot, vschneid, eagle.zhou, tao.jiang_2,
linux-imx, linux-kernel, linux-arm-kernel
On Tue, Aug 22, 2023 at 03:45:47PM +0800, Ming Qian wrote:
> kernel may try to wake up task with fake signal when freezing task,
> if the task is waiting event using wait_event_freezable,
> it's better to freeze the wait, instead of breaking it.
>
> otherwise the caller may need to retry the wait,
> maybe like below code:
>
> if (rc == -ERESTARTSYS && freezing(current)) {
> clear_thread_flag(TIF_SIGPENDING);
> goto again;
> }
I'm not sure I get it -- is there an actual problem, or are you trying
to optimize something?
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [EXT] Re: [PATCH] wait: don't wake up freezable wait by freezing fake signal
2023-09-25 10:08 ` Peter Zijlstra
@ 2023-09-26 2:43 ` Ming Qian
-1 siblings, 0 replies; 6+ messages in thread
From: Ming Qian @ 2023-09-26 2:43 UTC (permalink / raw)
To: Peter Zijlstra
Cc: mingo, juri.lelli, vincent.guittot, dietmar.eggemann, rostedt,
bsegall, mgorman, bristot, vschneid, Eagle Zhou, Tao Jiang,
dl-linux-imx, linux-kernel, linux-arm-kernel
>From: Peter Zijlstra <peterz@infradead.org>
>Sent: 2023年9月25日 18:08
>To: Ming Qian <ming.qian@nxp.com>
>Cc: mingo@redhat.com; juri.lelli@redhat.com; vincent.guittot@linaro.org;
>dietmar.eggemann@arm.com; rostedt@goodmis.org; bsegall@google.com;
>mgorman@suse.de; bristot@redhat.com; vschneid@redhat.com; Eagle Zhou
><eagle.zhou@nxp.com>; Tao Jiang <tao.jiang_2@nxp.com>; dl-linux-imx
><linux-imx@nxp.com>; linux-kernel@vger.kernel.org; linux-arm-
>kernel@lists.infradead.org
>Subject: [EXT] Re: [PATCH] wait: don't wake up freezable wait by freezing fake
>signal
>
>Caution: This is an external email. Please take care when clicking links or
>opening attachments. When in doubt, report the message using the 'Report
>this email' button
>
>
>On Tue, Aug 22, 2023 at 03:45:47PM +0800, Ming Qian wrote:
>> kernel may try to wake up task with fake signal when freezing task, if
>> the task is waiting event using wait_event_freezable, it's better to
>> freeze the wait, instead of breaking it.
>>
>> otherwise the caller may need to retry the wait, maybe like below
>> code:
>>
>> if (rc == -ERESTARTSYS && freezing(current)) {
>> clear_thread_flag(TIF_SIGPENDING);
>> goto again;
>> }
>
>I'm not sure I get it -- is there an actual problem, or are you trying to optimize
>something?
Hi Peter,
We have a driver that needs to interact with the daemon on nxp IMX8MP-EVK, Initially we use wait_event_interruptible to wait for a response from the daemon, but in our suspend test, sometimes we met failure which was caused by the waiting interrupted.
Then we use wait_event_freezable instead, but the problem remains. The above retry code should fix the problem, but we think it may be a common issue.
So we try to improve the wait_event_freezable, then we can pass our suspend test without any rety.
Ming
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [EXT] Re: [PATCH] wait: don't wake up freezable wait by freezing fake signal
@ 2023-09-26 2:43 ` Ming Qian
0 siblings, 0 replies; 6+ messages in thread
From: Ming Qian @ 2023-09-26 2:43 UTC (permalink / raw)
To: Peter Zijlstra
Cc: mingo, juri.lelli, vincent.guittot, dietmar.eggemann, rostedt,
bsegall, mgorman, bristot, vschneid, Eagle Zhou, Tao Jiang,
dl-linux-imx, linux-kernel, linux-arm-kernel
>From: Peter Zijlstra <peterz@infradead.org>
>Sent: 2023年9月25日 18:08
>To: Ming Qian <ming.qian@nxp.com>
>Cc: mingo@redhat.com; juri.lelli@redhat.com; vincent.guittot@linaro.org;
>dietmar.eggemann@arm.com; rostedt@goodmis.org; bsegall@google.com;
>mgorman@suse.de; bristot@redhat.com; vschneid@redhat.com; Eagle Zhou
><eagle.zhou@nxp.com>; Tao Jiang <tao.jiang_2@nxp.com>; dl-linux-imx
><linux-imx@nxp.com>; linux-kernel@vger.kernel.org; linux-arm-
>kernel@lists.infradead.org
>Subject: [EXT] Re: [PATCH] wait: don't wake up freezable wait by freezing fake
>signal
>
>Caution: This is an external email. Please take care when clicking links or
>opening attachments. When in doubt, report the message using the 'Report
>this email' button
>
>
>On Tue, Aug 22, 2023 at 03:45:47PM +0800, Ming Qian wrote:
>> kernel may try to wake up task with fake signal when freezing task, if
>> the task is waiting event using wait_event_freezable, it's better to
>> freeze the wait, instead of breaking it.
>>
>> otherwise the caller may need to retry the wait, maybe like below
>> code:
>>
>> if (rc == -ERESTARTSYS && freezing(current)) {
>> clear_thread_flag(TIF_SIGPENDING);
>> goto again;
>> }
>
>I'm not sure I get it -- is there an actual problem, or are you trying to optimize
>something?
Hi Peter,
We have a driver that needs to interact with the daemon on nxp IMX8MP-EVK, Initially we use wait_event_interruptible to wait for a response from the daemon, but in our suspend test, sometimes we met failure which was caused by the waiting interrupted.
Then we use wait_event_freezable instead, but the problem remains. The above retry code should fix the problem, but we think it may be a common issue.
So we try to improve the wait_event_freezable, then we can pass our suspend test without any rety.
Ming
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-09-26 2:43 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-08-22 7:45 [PATCH] wait: don't wake up freezable wait by freezing fake signal Ming Qian
2023-08-22 7:45 ` Ming Qian
2023-09-25 10:08 ` Peter Zijlstra
2023-09-25 10:08 ` Peter Zijlstra
2023-09-26 2:43 ` [EXT] " Ming Qian
2023-09-26 2:43 ` Ming Qian
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