From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Tue, 10 Feb 2009 15:52:37 +0000 (+0100)
Subject: softlockup: ensure the task has been switched out once
X-Git-Tag: v2.6.30-rc1~1^2~4
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cf2592f59c0e8ed4308adbdb2e0a88655379d579;p=pandora-kernel.git

softlockup: ensure the task has been switched out once

When we check if a task has been switched out since the last scan, we might
have a race condition on the following scenario:

- the task is freshly created and scheduled

- it puts its state to TASK_UNINTERRUPTIBLE and is not yet switched out

- check_hung_task() scans this task and will report a false positive because
  t->nvcsw + t->nivcsw == t->last_switch_count == 0

Add a check for such cases.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Mandeep Singh Baines <msb@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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