PM/Freezer: Thaw only kernel threads if freezing of kernel threads fails
Subsystems (2)
PATCH 1/1 PM/Freezer: Thaw only kernel threads if freezing of kernel threads fails
If freezing of kernel threads fails, we are expected to automatically thaw tasks in the error recovery path. However, at times, we encounter situations in which we would like the automatic error recovery path to thaw only the kernel threads, because we want to be able to do some more cleanup before we thaw userspace. Something like:
error = freeze_kernel_threads();
if (error) {
/* Do some cleanup */
/* Only then thaw userspace tasks*/
thaw_processes();
}An example of such a situation is where we freeze/thaw filesystems during suspend/hibernation. There, if freezing of kernel threads fails, we would like to thaw the frozen filesystems before thawing the userspace tasks.
So, modify freeze_kernel_threads() to thaw only kernel threads in case of freezing failure.
---
kernel/power/power.h | 26 ++++++++++++++++++++++++-- kernel/power/process.c | 7 +++++-- 2 files changed, 29 insertions(+), 4 deletions(-)
kernel/power/power.h +24 -2
@@ -231,8 +231,30 @@ extern int pm_test_level;#ifdef CONFIG_SUSPEND_FREEZER static inline int suspend_freeze_processes (void ) { -int error =freeze_processes (); -return error ? :freeze_kernel_threads (); +int error; + + error =freeze_processes (); + +/* +* freeze_processes() automatically thaws +* every task if freezing fails. So we need +* not do anything extra upon error. +*/ +if (error) + goto Finish; + + error =freeze_kernel_threads (); + +/* +* freeze_kernel_threads() thaws only kernel +* threads upon freezing failure. So we have +* to thaw the userspace tasks ourselves. +*/ +if (error) +thaw_processes (); + + Finish: +return error; }static inline void suspend_thaw_processes (void )
kernel/power/process.c +5 -2
@@ -143,7 +143,10 @@ int freeze_processes(void)/** * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator. * -* On success, returns 0. On failure, -errno and system is fully thawed. +* On success, returns 0. On failure, -errno and only the kernel threads are +* thawed, so as to give a chance to the caller to do additional cleanups +* (if any) before thawing the userspace tasks. So, it is the responsibility +* of the caller to thaw the userspace tasks, when the time is right. */ int freeze_kernel_threads (void ) {
@@ -159,7 +162,7 @@ int freeze_kernel_threads(void)BUG_ON (in_atomic ());if (error) -thaw_processes (); +thaw_kernel_threads ();return error; }
Quoted 14 lines · Srivatsa S. Bhat
If freezing of kernel threads fails, we are expected to automatically thaw tasks in the error recovery path. However, at times, we encounter situations in which we would like the automatic error recovery path to thaw only the kernel threads, because we want to be able to do some more cleanup before we thaw userspace. Something like:
error =
freeze_kernel_threads();if (error) { /* Do some cleanup */ /* Only then thaw userspace tasks*/ thaw_processes(); }
Quoted 8 lines
An example of such a situation is where we freeze/thaw filesystems during suspend/hibernation. There, if freezing of kernel threads fails, we would like to thaw the frozen filesystems before thawing the userspace tasks.
So, modify
freeze_kernel_threads()to thaw only kernel threads in case of freezing failure.Signed-off-by Srivatsa S. Bhat <[email protected]>
with nits below,
Quoted 30 lines
---
kernel/power/power.h | 26 ++++++++++++++++++++++++-- kernel/power/process.c | 7 +++++-- 2 files changed, 29 insertions(+), 4 deletions(-)kernel/power/power.h +14
-2@@ -231,8 +231,30 @@ extern int pm_test_level;#ifdef CONFIG_SUSPEND_FREEZER static inline int suspend_freeze_processes (void ) { -int error =freeze_processes (); -return error ? :freeze_kernel_threads (); +int error; + + error =freeze_processes (); + +/* +* freeze_processes() automatically thaws +* every task if freezing fails. So we need +* not do anything extra upon error. +*/ +if (error) + goto Finish; + + error =freeze_kernel_threads (); +
kernel/power/power.h extern int pm_test_level; · line 257
Quoted 10 lines
kernel/power/power.h +10
-0+/* +* freeze_kernel_threads() thaws only kernel +* threads upon freezing failure. So we have +* to thaw the userspace tasks ourselves. +*/ +if (error) +thaw_processes (); + + Finish: +return error;
Heh, the original ?: code was scary. That said, IMHO, the above seems a bit too verbose. Functions usually shouldn't have side effects on failure and the above code is usual in that sense and it would be nice to mention the reformatting (from cryptic to sane) in the commit log. Also, how many columns are you flowing the text to? It seems quite narrower than they usually should be.
Thanks.
Signature · 1 line
tejun
Quoted 62 lines · Tejun Heo
Quoted 14 lines · Srivatsa S. Bhat
If freezing of kernel threads fails, we are expected to automatically thaw tasks in the error recovery path. However, at times, we encounter situations in which we would like the automatic error recovery path to thaw only the kernel threads, because we want to be able to do some more cleanup before we thaw userspace. Something like:
error =
freeze_kernel_threads();if (error) { /* Do some cleanup */ /* Only then thaw userspace tasks*/ thaw_processes(); }Quoted 8 lines
An example of such a situation is where we freeze/thaw filesystems during suspend/hibernation. There, if freezing of kernel threads fails, we would like to thaw the frozen filesystems before thawing the userspace tasks.
So, modify
freeze_kernel_threads()to thaw only kernel threads in case of freezing failure.Signed-off-by Srivatsa S. Bhat <[email protected]>Acked-by Tejun Heo <[email protected]>with nits below,
Quoted 34 lines
---
kernel/power/power.h | 26 ++++++++++++++++++++++++-- kernel/power/process.c | 7 +++++-- 2 files changed, 29 insertions(+), 4 deletions(-)kernel/power/power.h +18
-2@@ -231,8 +231,30 @@ extern int pm_test_level;#ifdef CONFIG_SUSPEND_FREEZER static inline int suspend_freeze_processes (void ) { -int error =freeze_processes (); -return error ? :freeze_kernel_threads (); +int error; + + error =freeze_processes (); + +/* +* freeze_processes() automatically thaws +* every task if freezing fails. So we need +* not do anything extra upon error. +*/ +if (error) + goto Finish; + + error =freeze_kernel_threads (); + +/* +* freeze_kernel_threads() thaws only kernel +* threads upon freezing failure. So we have +* to thaw the userspace tasks ourselves.
Quoted 8 lines
kernel/power/power.h extern int pm_test_level; · line 257
Quoted 6 lines
kernel/power/power.h +6
-0+*/ +if (error) +thaw_processes (); + + Finish: +return error;Heh, the original ?: code was scary.
C'mon. ;-)
Quoted 6 lines
That said, IMHO, the above seems
a bit too verbose. Functions usually shouldn't have side effects on failure and the above code is usual in that sense and it would be nice to mention the reformatting (from cryptic to sane) in the commit log. Also, how many columns are you flowing the text to? It seems quite narrower than they usually should be.
I agree.
Srivatsa, care to resubmit?
Rafael
Srivatsa S. Bhat
Acked-by Tejun HeoQuoted 8 lines · Tejun Heo
Quoted 4 lines · Srivatsa S. Bhat
So, modify
freeze_kernel_threads()to thaw only kernel threads in case of freezing failure.Signed-off-by Srivatsa S. Bhat <[email protected]>Acked-by Tejun Heo <[email protected]>
Thanks a lot!
Quoted 7 lines
with nits below,
Heh, the original ?: code was scary. That said, IMHO, the above seems a bit too verbose. Functions usually shouldn't have side effects on failure and the above code is usual in that sense and it would be nice to mention the reformatting (from cryptic to sane) in the commit log.
Ok :-)
Quoted 2 lines
Also, how many columns are you flowing the text to? It seems quite narrower than they usually should be.
Oh right, I didn't give attention to that. I'll try to fit it in lesser number of lines. But, should I really cut short on the explanation itself? I remember Nigel had requested some comments on a different patch on roughly similar code path https://lkml.org/lkml/2012/1/28/111.
So I thought it would be a good idea to explicitly document the differences, to be clear...
Here is the updated patch:
From: Srivatsa S. Bhat <[email protected]>
Subject: [PATCH] PM/Freezer: Thaw only kernel threads if freezing of kernel threads fails
If freezing of kernel threads fails, we are expected to automatically thaw tasks in the error recovery path. However, at times, we encounter situations in which we would like the automatic error recovery path to thaw only the kernel threads, because we want to be able to do some more cleanup before we thaw userspace. Something like:
error = freeze_kernel_threads();
if (error) {
/* Do some cleanup */
/* Only then thaw userspace tasks*/
thaw_processes();
}An example of such a situation is where we freeze/thaw filesystems during suspend/hibernation. There, if freezing of kernel threads fails, we would like to thaw the frozen filesystems before thawing the userspace tasks.
So, modify freeze_kernel_threads() to thaw only kernel threads in case of freezing failure. And change suspend_freeze_processes() accordingly. (At the same time, let us also get rid of the rather cryptic usage of the conditional operator (:?) in that function.)
---
kernel/power/power.h | 24 ++++++++++++++++++++++-- kernel/power/process.c | 7 +++++-- 2 files changed, 27 insertions(+), 4 deletions(-)
kernel/power/power.h +22 -2
@@ -231,8 +231,28 @@ extern int pm_test_level;#ifdef CONFIG_SUSPEND_FREEZER static inline int suspend_freeze_processes (void ) { -int error =freeze_processes (); -return error ? :freeze_kernel_threads (); +int error; + + error =freeze_processes (); + +/* +* freeze_processes() automatically thaws every task if freezing +* fails. So we need not do anything extra upon error. +*/ +if (error) + goto Finish; + + error =freeze_kernel_threads (); + +/* +* freeze_kernel_threads() thaws only kernel threads upon freezing +* failure. So we have to thaw the userspace tasks ourselves. +*/ +if (error) +thaw_processes (); + + Finish: +return error; }static inline void suspend_thaw_processes (void )
kernel/power/process.c +5 -2
@@ -143,7 +143,10 @@ int freeze_processes(void)/** * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator. * -* On success, returns 0. On failure, -errno and system is fully thawed. +* On success, returns 0. On failure, -errno and only the kernel threads are +* thawed, so as to give a chance to the caller to do additional cleanups +* (if any) before thawing the userspace tasks. So, it is the responsibility +* of the caller to thaw the userspace tasks, when the time is right. */ int freeze_kernel_threads (void ) {
@@ -159,7 +162,7 @@ int freeze_kernel_threads(void)BUG_ON (in_atomic ());if (error) -thaw_processes (); +thaw_kernel_threads ();return error; }
Nigel Cunningham
Acked-byHi
Quoted 9 lines · Srivatsa S. Bhat
Quoted 7 lines · Tejun Heo
Quoted 4 lines · Srivatsa S. Bhat
So, modify
freeze_kernel_threads()to thaw only kernel threads in case of freezing failure.Signed-off-by Srivatsa S. Bhat <[email protected]>Acked-by Tejun Heo <[email protected]>
Regards,
Nigel
Signature · 3 lines
Evolution (n): A hypothetical process whereby improbable events occur with alarming frequency, order arises from chaos, and no one is given credit.
Rafael J. Wysocki
AppliedQuoted 59 lines · Srivatsa S. Bhat
Quoted 8 lines · Tejun Heo
Quoted 4 lines · Srivatsa S. Bhat
So, modify
freeze_kernel_threads()to thaw only kernel threads in case of freezing failure.Signed-off-by Srivatsa S. Bhat <[email protected]>Acked-by Tejun Heo <[email protected]>Thanks a lot!
Quoted 7 lines
with nits below,
Heh, the original ?: code was scary. That said, IMHO, the above seems a bit too verbose. Functions usually shouldn't have side effects on failure and the above code is usual in that sense and it would be nice to mention the reformatting (from cryptic to sane) in the commit log.
Ok :-)
Quoted 2 lines
Also, how many columns are you flowing the text to? It seems quite narrower than they usually should be.
Oh right, I didn't give attention to that. I'll try to fit it in lesser number of lines. But, should I really cut short on the explanation itself? I remember Nigel had requested some comments on a different patch on roughly similar code path https://lkml.org/lkml/2012/1/28/111.
So I thought it would be a good idea to explicitly document the differences, to be clear...Here is the updated patch:
From: Srivatsa S. Bhat <[email protected]>
Subject: [PATCH] PM/Freezer: Thaw only kernel threads if freezing of kernel threads failsIf freezing of kernel threads fails, we are expected to automatically thaw tasks in the error recovery path. However, at times, we encounter situations in which we would like the automatic error recovery path to thaw only the kernel threads, because we want to be able to do some more cleanup before we thaw userspace. Something like:
error =
freeze_kernel_threads();if (error) { /* Do some cleanup */ /* Only then thaw userspace tasks*/ thaw_processes(); }An example of such a situation is where we freeze/thaw filesystems during suspend/hibernation. There, if freezing of kernel threads fails, we would like to thaw the frozen filesystems before thawing the userspace tasks.
Quoted 7 lines
So, modify
freeze_kernel_threads()to thaw only kernel threads in case of freezing failure. And changesuspend_freeze_processes()accordingly. (At the same time, let us also get rid of the rather cryptic usage of the conditional operator (:?) in that function.)Signed-off-by Srivatsa S. Bhat <[email protected]>Acked-by Tejun Heo <[email protected]>
Applied.
Thanks,
Rafael
Quoted 70 lines
---
kernel/power/power.h | 24 ++++++++++++++++++++++-- kernel/power/process.c | 7 +++++-- 2 files changed, 27 insertions(+), 4 deletions(-)kernel/power/power.h +22
-2@@ -231,8 +231,28 @@ extern int pm_test_level;#ifdef CONFIG_SUSPEND_FREEZER static inline int suspend_freeze_processes (void ) { -int error =freeze_processes (); -return error ? :freeze_kernel_threads (); +int error; + + error =freeze_processes (); + +/* +* freeze_processes() automatically thaws every task if freezing +* fails. So we need not do anything extra upon error. +*/ +if (error) + goto Finish; + + error =freeze_kernel_threads (); + +/* +* freeze_kernel_threads() thaws only kernel threads upon freezing +* failure. So we have to thaw the userspace tasks ourselves. +*/ +if (error) +thaw_processes (); + + Finish: +return error; }static inline void suspend_thaw_processes (void )kernel/power/process.c +5
-2@@ -143,7 +143,10 @@ int freeze_processes(void)/** * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator. * -* On success, returns 0. On failure, -errno and system is fully thawed. +* On success, returns 0. On failure, -errno and only the kernel threads are +* thawed, so as to give a chance to the caller to do additional cleanups +* (if any) before thawing the userspace tasks. So, it is the responsibility +* of the caller to thaw the userspace tasks, when the time is right. */ int freeze_kernel_threads (void ) {@@ -159,7 +162,7 @@ int freeze_kernel_threads(void)BUG_ON (in_atomic ());if (error) -thaw_processes (); +thaw_kernel_threads ();return error; }
PATCH 1/1 PM/Freezer: Thaw only kernel threads if freezing of kernel threads fails
In reply to Srivatsa S. BhatQuoted 22 lines · Srivatsa S. Bhat
From: Srivatsa S. Bhat <[email protected]>
Subject: [PATCH] PM/Freezer: Thaw only kernel threads if freezing of kernel threads failsIf freezing of kernel threads fails, we are expected to automatically thaw tasks in the error recovery path. However, at times, we encounter situations in which we would like the automatic error recovery path to thaw only the kernel threads, because we want to be able to do some more cleanup before we thaw userspace. Something like:
error =
freeze_kernel_threads();if (error) { /* Do some cleanup */ /* Only then thaw userspace tasks*/ thaw_processes(); }An example of such a situation is where we freeze/thaw filesystems during suspend/hibernation. There, if freezing of kernel threads fails, we would like to thaw the frozen filesystems before thawing the userspace tasks.
Quoted 8 lines
So, modify
freeze_kernel_threads()to thaw only kernel threads in case of freezing failure. And changesuspend_freeze_processes()accordingly. (At the same time, let us also get rid of the rather cryptic usage of the conditional operator (:?) in that function.)Signed-off-by Srivatsa S. Bhat <[email protected]>Acked-by Tejun Heo <[email protected]>---
Hi Rafael,
I have reworked the changelog of this patch to indicate that this fixes a regression. Here is the updated patch:
From: Srivatsa S. Bhat <[email protected]>
Subject: [PATCH] PM/Freezer: Thaw only kernel threads if freezing of kernel threads fails
If freezing of kernel threads fails, we are expected to automatically thaw tasks in the error recovery path. However, at times, we encounter situations in which we would like the automatic error recovery path to thaw only the kernel threads, because we want to be able to do some more cleanup before we thaw userspace. Something like:
error = freeze_kernel_threads();
if (error) {
/* Do some cleanup */
/* Only then thaw userspace tasks*/
thaw_processes();
}An example of such a situation is where we freeze/thaw filesystems during suspend/hibernation. There, if freezing of kernel threads fails, we would like to thaw the frozen filesystems before thawing the userspace tasks.
So, modify freeze_kernel_threads() to thaw only kernel threads in case of freezing failure.
This also fixes a regression in hibernation_snapshot() by which, if the freezing of kernel threads happened to fail, we would thaw every task (including userspace tasks) before freeing the memory pre-allocated for the purpose of hibernation (which could be quite significant).
So, thawing only kernel threads upon failure to freeze kernel threads will give us a chance to free up the pre-allocated memory before thawing userspace tasks, thereby reducing the probability of unreasonable memory allocation failures.
And while we are updating suspend_freeze_processes() to adapt to this change, let us also get rid of the rather cryptic usage of the conditional operator (:?) in that function.
---
kernel/power/power.h | 24 ++++++++++++++++++++++-- kernel/power/process.c | 7 +++++-- 2 files changed, 27 insertions(+), 4 deletions(-)
kernel/power/power.h +22 -2
@@ -231,8 +231,28 @@ extern int pm_test_level;#ifdef CONFIG_SUSPEND_FREEZER static inline int suspend_freeze_processes (void ) { -int error =freeze_processes (); -return error ? :freeze_kernel_threads (); +int error; + + error =freeze_processes (); + +/* +* freeze_processes() automatically thaws every task if freezing +* fails. So we need not do anything extra upon error. +*/ +if (error) + goto Finish; + + error =freeze_kernel_threads (); + +/* +* freeze_kernel_threads() thaws only kernel threads upon freezing +* failure. So we have to thaw the userspace tasks ourselves. +*/ +if (error) +thaw_processes (); + + Finish: +return error; }static inline void suspend_thaw_processes (void )
kernel/power/process.c +5 -2
@@ -143,7 +143,10 @@ int freeze_processes(void)/** * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator. * -* On success, returns 0. On failure, -errno and system is fully thawed. +* On success, returns 0. On failure, -errno and only the kernel threads are +* thawed, so as to give a chance to the caller to do additional cleanups +* (if any) before thawing the userspace tasks. So, it is the responsibility +* of the caller to thaw the userspace tasks, when the time is right. */ int freeze_kernel_threads (void ) {
@@ -159,7 +162,7 @@ int freeze_kernel_threads(void)BUG_ON (in_atomic ());if (error) -thaw_processes (); +thaw_kernel_threads ();return error; }
Quoted 34 lines · Srivatsa S. Bhat
Quoted 22 lines · Srivatsa S. Bhat
From: Srivatsa S. Bhat <[email protected]>
Subject: [PATCH] PM/Freezer: Thaw only kernel threads if freezing of kernel threads failsIf freezing of kernel threads fails, we are expected to automatically thaw tasks in the error recovery path. However, at times, we encounter situations in which we would like the automatic error recovery path to thaw only the kernel threads, because we want to be able to do some more cleanup before we thaw userspace. Something like:
error =
freeze_kernel_threads();if (error) { /* Do some cleanup */ /* Only then thaw userspace tasks*/ thaw_processes(); }An example of such a situation is where we freeze/thaw filesystems during suspend/hibernation. There, if freezing of kernel threads fails, we would like to thaw the frozen filesystems before thawing the userspace tasks.
Quoted 8 lines
So, modify
freeze_kernel_threads()to thaw only kernel threads in case of freezing failure. And changesuspend_freeze_processes()accordingly. (At the same time, let us also get rid of the rather cryptic usage of the conditional operator (:?) in that function.)Signed-off-by Srivatsa S. Bhat <[email protected]>Acked-by Tejun Heo <[email protected]>---
Quoted 4 lines
Hi Rafael,
I have reworked the changelog of this patch to indicate that this fixes a regression. Here is the updated patch:
Well, I've already fixed that up in my tree, but thanks anyway. :-)
Rafael
Quoted 9 lines · Rafael J. Wysocki
Quoted 5 lines · Srivatsa S. Bhat
On 02/02/2012 04:29 AM, Srivatsa S. Bhat wrote:
Hi Rafael,I have reworked the changelog of this patch to indicate that this fixes a regression. Here is the updated patch:
Well, I've already fixed that up in my tree, but thanks anyway. :-)
Nicer if gurus open wider windows for patches received, no?
Good weekend
Hillf
Quoted 5 lines · Hillf Danton
Quoted 4 lines · Rafael J. Wysocki
Quoted 3 lines · Srivatsa S. Bhat
On 02/02/2012 04:29 AM, Srivatsa S. Bhat wrote:
Hi Rafael,
Quoted 7 lines
Quoted 5 lines
Quoted 2 lines
I have reworked the changelog of this patch to indicate that this fixes a regression. Here is the updated patch:
Well, I've already fixed that up in my tree, but thanks anyway. :-)
Nicer if gurus open wider windows for patches received, no?
Well, I hope Srivatsa didn't mind. :-)
Thanks,
Rafael
Quoted 5 lines · Hillf Danton
Quoted 4 lines · Rafael J. Wysocki
Quoted 3 lines · Srivatsa S. Bhat
On 02/02/2012 04:29 AM, Srivatsa S. Bhat wrote:
Hi Rafael,
Quoted 8 lines
Quoted 5 lines
Quoted 2 lines
I have reworked the changelog of this patch to indicate that this fixes a regression. Here is the updated patch:
Well, I've already fixed that up in my tree, but thanks anyway. :-)
Nicer if gurus open wider windows for patches received, no?
I am not quite sure what you meant by that, but just in case you got the wrong idea by any chance, let me clarify:
Working with Rafael has *always* been an immensely pleasurable experience! There is absolutely no doubt in that :-)
So there really is no reason to feel bad about the above incident :-)
Regards,
Srivatsa S. Bhat
Quoted 17 lines · Srivatsa S. Bhat
Quoted 5 lines · Hillf Danton
Quoted 4 lines · Rafael J. Wysocki
Quoted 3 lines · Srivatsa S. Bhat
On 02/02/2012 04:29 AM, Srivatsa S. Bhat wrote:
Hi Rafael,Quoted 8 lines
Quoted 5 lines
Quoted 2 lines
I have reworked the changelog of this patch to indicate that this fixes a regression. Here is the updated patch:
Well, I've already fixed that up in my tree, but thanks anyway. :-)
Nicer if gurus open wider windows for patches received, no?
Quoted 5 lines
I am not quite sure what you meant by that, but just in case you got the wrong idea by any chance, let me clarify:
Working with Rafael has *always* been an immensely pleasurable experience! There is absolutely no doubt in that :-)
Well, thanks! :-)
Rafael
Quoted 17 lines · Srivatsa S. Bhat
Quoted 5 lines · Hillf Danton
Quoted 4 lines · Rafael J. Wysocki
Quoted 3 lines · Srivatsa S. Bhat
On 02/02/2012 04:29 AM, Srivatsa S. Bhat wrote:
Hi Rafael,Quoted 8 lines
Quoted 5 lines
Quoted 2 lines
I have reworked the changelog of this patch to indicate that this fixes a regression. Here is the updated patch:
Well, I've already fixed that up in my tree, but thanks anyway. :-)
Nicer if gurus open wider windows for patches received, no?
Quoted 8 lines
I am not quite sure what you meant by that, but just in case you got the wrong idea by any chance, let me clarify:
Working with Rafael has *always* been an immensely pleasurable experience! There is absolutely no doubt in that :-)
So there really is no reason to feel bad about the above incident :-)
Yes, no reason not to keep mind open.
Good weekend
Hillf