Messages in this thread Patch in this message | | | Date | Wed, 16 Dec 2009 19:56:33 -0800 | From | Greg KH <> | Subject | [096/151] xen: explicitly create/destroy stop_machine workqueues outside suspend/resume region. |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
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From: Ian Campbell <ian.campbell@citrix.com>
commit b4606f2165153833247823e8c04c5e88cb3d298b upstream.
I have observed cases where the implicit stop_machine_destroy() done by stop_machine() hangs while destroying the workqueues, specifically in kthread_stop(). This seems to be because timer ticks are not restarted until after stop_machine() returns.
Fortunately stop_machine provides a facility to pre-create/post-destroy the workqueues so use this to ensure that workqueues are only destroyed after everything is really up and running again.
I only actually observed this failure with 2.6.30. It seems that newer kernels are somehow more robust against doing kthread_stop() without timer interrupts (I tried some backports of some likely looking candidates but did not track down the commit which added this robustness). However this change seems like a reasonable belt&braces thing to do.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/xen/manage.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
--- a/drivers/xen/manage.c +++ b/drivers/xen/manage.c @@ -79,6 +79,12 @@ static void do_suspend(void) shutting_down = SHUTDOWN_SUSPEND; + err = stop_machine_create(); + if (err) { + printk(KERN_ERR "xen suspend: failed to setup stop_machine %d\n", err); + goto out; + } + #ifdef CONFIG_PREEMPT /* If the kernel is preemptible, we need to freeze all the processes to prevent them from being in the middle of a pagetable update @@ -86,7 +92,7 @@ static void do_suspend(void) err = freeze_processes(); if (err) { printk(KERN_ERR "xen suspend: freeze failed %d\n", err); - goto out; + goto out_destroy_sm; } #endif @@ -129,7 +135,11 @@ out_resume: out_thaw: #ifdef CONFIG_PREEMPT thaw_processes(); + +out_destroy_sm: #endif + stop_machine_destroy(); + out: shutting_down = SHUTDOWN_INVALID; }
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