From: Tejun Heo Date: Fri, 26 Nov 2010 22:07:27 +0000 (+0100) Subject: Freezer: Fix a race during freezing of TASK_STOPPED tasks X-Git-Tag: v2.6.38-rc1~443^2~16 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8cfe400ca54fd1ed96f962bea5f7e20b09b6d69f;p=pandora-kernel.git Freezer: Fix a race during freezing of TASK_STOPPED tasks After calling freeze_task(), try_to_freeze_tasks() see whether the task is stopped or traced and if so, considers it to be frozen; however, nothing guarantees that either the task being frozen sees TIF_FREEZE or the freezer sees TASK_STOPPED -> TASK_RUNNING transition. The task being frozen may wake up and not see TIF_FREEZE while the freezer fails to notice the transition and believes the task is still stopped. This patch fixes the race by making freeze_task() always go through fake_signal_wake_up() for applicable tasks. The function goes through the target task's scheduler lock and thus guarantees that either the target sees TIF_FREEZE or try_to_freeze_task() sees TASK_RUNNING. Signed-off-by: Tejun Heo Signed-off-by: Rafael J. Wysocki --- Reading git-diff-tree failed