From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Date: Wed, 24 Aug 2011 16:54:24 +0000 (-0700)
Subject: xen: use non-tracing preempt in xen_clocksource_read()
X-Git-Tag: v3.1-rc7~68^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f1c39625d63c9f8eba8f036429c10a9cb9e32920;p=pandora-kernel.git

xen: use non-tracing preempt in xen_clocksource_read()

The tracing code used sched_clock() to get tracing timestamps, which
ends up calling xen_clocksource_read().  xen_clocksource_read() must
disable preemption, but if preemption tracing is enabled, this results
in infinite recursion.

I've only noticed this when boot-time tracing tests are enabled, but it
seems like a generic bug.  It looks like it would also affect
kvm_clocksource_read().

Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
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