From: Benjamin Herrenschmidt Date: Fri, 16 Apr 2010 21:20:00 +0000 (+0200) Subject: mutex: Don't spin when the owner CPU is offline or other weird cases X-Git-Tag: v2.6.34-rc7~31^2~2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4b402210486c6414fe5fbfd85934a0a22da56b04;p=pandora-kernel.git mutex: Don't spin when the owner CPU is offline or other weird cases Due to recent load-balancer changes that delay the task migration to the next wakeup, the adaptive mutex spinning ends up in a live lock when the owner's CPU gets offlined because the cpu_online() check lives before the owner running check. This patch changes mutex_spin_on_owner() to return 0 (don't spin) in any case where we aren't sure about the owner struct validity or CPU number, and if the said CPU is offline. There is no point going back & re-evaluate spinning in corner cases like that, let's just go to sleep. Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Peter Zijlstra LKML-Reference: <1271212509.13059.135.camel@pasglop> Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed