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authorSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>2012-02-03 22:22:41 +0100
committerRafael J. Wysocki <rjw@sisk.pl>2012-02-04 22:23:05 +0100
commit379e0be812ab8a2a351e784b0c987788f5123090 (patch)
tree70f1e7ac57e198d0a94a89a65933da9a2ca35ccc
parentfe9161db2e6053da21e4649d77bbefaf3030b11d (diff)
downloadop-kernel-dev-379e0be812ab8a2a351e784b0c987788f5123090.zip
op-kernel-dev-379e0be812ab8a2a351e784b0c987788f5123090.tar.gz
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.) [rjw: In fact, this patch fixes a regression introduced during the 3.3 merge window, because without it thaw_processes() may be called before swsusp_free() in some situations and that may lead to massive memory allocation failures.] Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Nigel Cunningham <nigel@tuxonice.net> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
-rw-r--r--kernel/power/power.h24
-rw-r--r--kernel/power/process.c7
2 files changed, 27 insertions, 4 deletions
diff --git a/kernel/power/power.h b/kernel/power/power.h
index 0c4defe..21724ee 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -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)
diff --git a/kernel/power/process.c b/kernel/power/process.c
index eeca003..7e42645 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -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;
}
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