Rafael J. Wysocki 8a102eed9c [PATCH] PM: Fix SMP races in the freezer ... Currently, to tell a task that it should go to the refrigerator, we set the PF_FREEZE flag for it and send a fake signal to it. Unfortunately there are two SMP-related problems with this approach. First, a task running on another CPU may be updating its flags while the freezer attempts to set PF_FREEZE for it and this may leave the task's flags in an inconsistent state. Second, there is a potential race between freeze_process() and refrigerator() in which freeze_process() running on one CPU is reading a task's PF_FREEZE flag while refrigerator() running on another CPU has just set PF_FROZEN for the same task and attempts to reset PF_FREEZE for it. If the refrigerator wins the race, freeze_process() will state that PF_FREEZE hasn't been set for the task and will set it unnecessarily, so the task will go to the refrigerator once again after it's been thawed. To solve first of these problems we need to stop using PF_FREEZE to tell tasks that they should go to the refrigerator. Instead, we can introduce a special TIF_*** flag and use it for this purpose, since it is allowed to change the other tasks' TIF_*** flags and there are special calls for it. To avoid the freeze_process()-refrigerator() race we can make freeze_process() to always check the task's PF_FROZEN flag after it's read its "freeze" flag. We should also make sure that refrigerator() will always reset the task's "freeze" flag after it's set PF_FROZEN for it. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Cc: Russell King <rmk@arm.linux.org.uk> Cc: David Howells <dhowells@redhat.com> Cc: Andi Kleen <ak@muc.de> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>		2006-12-13 09:05:49 -08:00
..
console.c	[PATCH] Fix build failure in recent pm_prepare_* changes.	2006-02-07 16:12:33 -08:00
disk.c	[PATCH] swsusp: kill write-only variable	2006-12-07 08:39:29 -08:00
Kconfig	[PATCH] swsusp: Support i386 systems with PAE or without PSE	2006-12-07 08:39:28 -08:00
main.c	[PATCH] Export pm_suspend for the shared APM emulation	2006-12-07 08:39:32 -08:00
Makefile	[PATCH] Disable CPU hotplug during suspend	2006-09-26 08:48:59 -07:00
pm.c	[PATCH] remove kernel/power/pm.c:pm_unregister_all()	2006-07-12 16:09:08 -07:00
power.h	[PATCH] convert pm_sem to a mutex	2006-12-07 08:39:28 -08:00
poweroff.c	WorkStruct: Pass the work_struct pointer instead of context data	2006-11-22 14:55:48 +00:00
process.c	[PATCH] PM: Fix SMP races in the freezer	2006-12-13 09:05:49 -08:00
snapshot.c	[PATCH] swsusp: Fix labels	2006-12-07 08:39:28 -08:00
swap.c	[PATCH] swsusp: Fix labels	2006-12-07 08:39:28 -08:00
swsusp.c	[PATCH] swsusp: Fix labels	2006-12-07 08:39:28 -08:00
user.c	[PATCH] struct seq_operations and struct file_operations constification	2006-12-07 08:39:46 -08:00