Messages in this thread Patch in this message | | | Date | Thu, 01 Dec 2011 21:58:22 +0530 | From | "Srivatsa S. Bhat" <> | Subject | Re: [PATCH] PM / Hibernate: Thaw processes in SNAPSHOT_CREATE_IMAGE ioctl error/test paths |
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On 12/01/2011 09:17 PM, Tejun Heo wrote:
> On Thu, Dec 01, 2011 at 06:45:37PM +0530, Srivatsa S. Bhat wrote: >> Commit 2aede851ddf08666f68ffc17be446420e9d2a056 (PM / Hibernate: Freeze >> kernel threads after preallocating memory) moved the freezing of kernel >> threads to hibernation_snapshot() function. >> >> So now, if the call to hibernation_snapshot() fails or returns early due >> to a successful hibernation test, the caller has to thaw processes to >> ensure that the system gets back to its original state. >> >> But in SNAPSHOT_CREATE_IMAGE hibernation ioctl, the caller does not thaw >> processes. Fix this issue. But note that if hibernation_snapshot() returned >> due to a successful freezer test, we still send the value of 'in_suspend' >> (which is now 0) to userspace, because we are not in an error path per-se, >> and moreover, the value of in_suspend correctly depicts the situation here. >> >> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> > > Is this still applicable on top of pm-freezer branch? >
Well, yes, but not in this form. Thanks for bringing that up!
If the call to hibernation_snapshot() returns an error, we need not do anything since your freezer changes handle that case and call thaw_processes() automatically. But in case of return due to a successful freezer test, we would need to explicitly thaw processes since the freezer successfully froze them in the previous step.
So the following patch would do that, for the pm-freezer branch:
--- From: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Subject: [PATCH] PM / Hibernate: Thaw processes in SNAPSHOT_CREATE_IMAGE ioctl test path
Commit 2aede851ddf08666f68ffc17be446420e9d2a056 (PM / Hibernate: Freeze kernel threads after preallocating memory) moved the freezing of kernel threads to hibernation_snapshot() function.
So now, if the call to hibernation_snapshot() returns early due to a successful hibernation test, the caller has to thaw processes to ensure that the system gets back to its original state.
But in SNAPSHOT_CREATE_IMAGE hibernation ioctl, the caller does not thaw processes in case hibernation_snapshot() returned due to a successful freezer test. Fix this issue. But note we still send the value of 'in_suspend' (which is now 0) to userspace, because we are not in an error path per-se, and moreover, the value of in_suspend correctly depicts the situation here.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> ---
kernel/power/hibernate.c | 2 +- kernel/power/power.h | 2 ++ kernel/power/user.c | 11 ++++++++--- 3 files changed, 11 insertions(+), 4 deletions(-)
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c index 80c2d90..57bab63 100644 --- a/kernel/power/hibernate.c +++ b/kernel/power/hibernate.c @@ -55,7 +55,7 @@ enum { static int hibernation_mode = HIBERNATION_SHUTDOWN; -static bool freezer_test_done; +bool freezer_test_done; static const struct platform_hibernation_ops *hibernation_ops; diff --git a/kernel/power/power.h b/kernel/power/power.h index 23a2db1..0c4defe 100644 --- a/kernel/power/power.h +++ b/kernel/power/power.h @@ -50,6 +50,8 @@ static inline char *check_image_kernel(struct swsusp_info *info) #define SPARE_PAGES ((1024 * 1024) >> PAGE_SHIFT) /* kernel/power/hibernate.c */ +extern bool freezer_test_done; + extern int hibernation_snapshot(int platform_mode); extern int hibernation_restore(int platform_mode); extern int hibernation_platform_enter(void); diff --git a/kernel/power/user.c b/kernel/power/user.c index 7cc3f5b..c202e2e 100644 --- a/kernel/power/user.c +++ b/kernel/power/user.c @@ -281,10 +281,15 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd, } pm_restore_gfp_mask(); error = hibernation_snapshot(data->platform_support); - if (!error) + if (!error) { error = put_user(in_suspend, (int __user *)arg); - if (!error) - data->ready = 1; + if (!error && !freezer_test_done) + data->ready = 1; + if (freezer_test_done) { + freezer_test_done = false; + thaw_processes(); + } + } break; case SNAPSHOT_ATOMIC_RESTORE:
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