From: Tejun Heo Date: Tue, 16 Oct 2012 22:03:14 +0000 (-0700) Subject: freezer: add missing mb's to freezer_count() and freezer_should_skip() X-Git-Tag: v3.2.36~138 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=26e5f795726ed11feff7125d727377a3eb231403;p=pandora-kernel.git freezer: add missing mb's to freezer_count() and freezer_should_skip() commit dd67d32dbc5de299d70cc9e10c6c1e29ffa56b92 upstream. A task is considered frozen enough between freezer_do_not_count() and freezer_count() and freezers use freezer_should_skip() to test this condition. This supposedly works because freezer_count() always calls try_to_freezer() after clearing %PF_FREEZER_SKIP. However, there currently is nothing which guarantees that freezer_count() sees %true freezing() after clearing %PF_FREEZER_SKIP when freezing is in progress, and vice-versa. A task can escape the freezing condition in effect by freezer_count() seeing !freezing() and freezer_should_skip() seeing %PF_FREEZER_SKIP. This patch adds smp_mb()'s to freezer_count() and freezer_should_skip() such that either %true freezing() is visible to freezer_count() or !PF_FREEZER_SKIP is visible to freezer_should_skip(). Signed-off-by: Tejun Heo Cc: Oleg Nesterov Cc: Rafael J. Wysocki [bwh: Backported to 3.2: - Adjust context and indentation - freezer_do_not_count() and freezer_count() are no-ops for kernel tasks] Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed