| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.15 020/109] xen/manage: fix potential deadlock when resuming the console | Date | Sat, 26 Jul 2014 12:01:42 -0700 |
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3.15-stable review patch. If anyone has any objections, please let me know.
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From: David Vrabel <david.vrabel@citrix.com>
commit 1b6478231c6f5f844185acb32045cf195028cfce upstream.
Calling xen_console_resume() in xen_suspend() causes a warning because it locks irq_mapping_update_lock (a mutex) and this may sleep. If a userspace process is using the evtchn device then this mutex may be locked at the point of the stop_machine() call and xen_console_resume() would then deadlock.
Resuming the console after stop_machine() returns avoids this deadlock.
Signed-off-by: David Vrabel <david.vrabel@citrix.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/xen/manage.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/xen/manage.c +++ b/drivers/xen/manage.c @@ -109,7 +109,6 @@ static int xen_suspend(void *data) if (!si->cancelled) { xen_irq_resume(); - xen_console_resume(); xen_timer_resume(); } @@ -166,6 +165,10 @@ static void do_suspend(void) err = stop_machine(xen_suspend, &si, cpumask_of(0)); + /* Resume console as early as possible. */ + if (!si.cancelled) + xen_console_resume(); + raw_notifier_call_chain(&xen_resume_notifier, 0, NULL); dpm_resume_start(si.cancelled ? PMSG_THAW : PMSG_RESTORE);
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