linux-kernel - freezer: should barriers be smp ?

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Message-ID: <BANLkTi=F-C-vwX4PGGfbkdTBw3OWL-twfg@mail.gmail.com>
Date:	Wed, 13 Apr 2011 02:14:39 -0400
From:	Mike Frysinger <vapier@...too.org>
To:	Pavel Machek <pavel@....cz>, "Rafael J. Wysocki" <rjw@...k.pl>
Cc:	linux-kernel@...r.kernel.org,
	uclinux-dist-devel@...ckfin.uclinux.org,
	linux-pm@...ts.linux-foundation.org
Subject: freezer: should barriers be smp ?

when we suspend/resume Blackfin SMP systems, we notice that the
freezer code runs on multiple cores.  this is of course what you want
-- freeze processes in parallel.  however, the code only uses non-smp
based barriers which causes us problems ... our cores need software
support to keep caches in sync, so our smp barriers do just that.  but
the non-smp barriers do not, and so the frozen/thawed processes
randomly get stuck in the wrong task state.

thinking about it, shouldnt the freezer code be using smp barriers ?
the point is to make sure that the updates are seen across all cores
are not just the current one ?
-mike
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