From: Michael Ellerman Date: Thu, 7 Aug 2014 05:36:18 +0000 (+1000) Subject: powerpc: Add smp_mb()s to arch_spin_unlock_wait() X-Git-Tag: omap-for-v3.17/fixes-against-rc2~65^2~21 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=78e05b1421fa41ae8457701140933baa5e7d9479;p=pandora-kernel.git powerpc: Add smp_mb()s to arch_spin_unlock_wait() Similar to the previous commit which described why we need to add a barrier to arch_spin_is_locked(), we have a similar problem with spin_unlock_wait(). We need a barrier on entry to ensure any spinlock we have previously taken is visibly locked prior to the load of lock->slock. It's also not clear if spin_unlock_wait() is intended to have ACQUIRE semantics. For now be conservative and add a barrier on exit to give it ACQUIRE semantics. Signed-off-by: Michael Ellerman Signed-off-by: Benjamin Herrenschmidt --- Reading git-diff-tree failed