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Date: Thu, 27 Oct 2016 17:34:06 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: Brian Norris <briannorris@...omium.org> Cc: "Rafael J . Wysocki" <rjw@...ysocki.net>, Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>, linux-kernel@...r.kernel.org, Doug Anderson <dianders@...omium.org>, Brian Norris <computersforpeace@...il.com>, Jeffy Chen <jeffy.chen@...k-chips.com>, linux-pm@...r.kernel.org, Chuansheng Liu <chuansheng.liu@...el.com>, Dmitry Torokhov <dmitry.torokhov@...il.com> Subject: Re: [PATCH 2/2] PM / sleep: don't suspend parent when async child suspend_{noirq,early} fails On Wed, Oct 19, 2016 at 05:46:11PM -0700, Brian Norris wrote: > Ugh, as I hope the patch context makes clear, the subject should be > > s/early/late/ > > as should the body of the commit message. > > On Wed, Oct 19, 2016 at 05:26:10PM -0700, Brian Norris wrote: > > Consider two devices, A and B, where B is a child of A, and B utilizes > > asynchronous suspend (it does not matter whether A is sync or async). If > > B fails to suspend_noirq() or suspend_early(), or is interrupted by a > > s/early/late/ > > > wakeup (pm_wakeup_pending()), then it aborts and sets the async_error > > variable. However, device A does not (immediately) check the async_error > > variable; it may continue to run its own suspend_noirq()/suspend_early() > > s/early/late/ > > > callback. This is bad. > > > > We can resolve this problem by checking the async_error flag after > > waiting for children to suspend, using the same logic for the noirq and > > late suspend cases as we already do for __device_suspend(). > > > > It's easy to observe this erroneous behavior by, for example, forcing a > > device to sleep a bit in its suspend_noirq() (to ensure the parent is > > waiting for the child to complete), then return an error, and watch the > > parent suspend_noirq() still get called. (Or similarly, fake a wakeup > > event at the right (or is it wrong?) time.) > > > > Fixes: de377b397272 ("PM / sleep: Asynchronous threads for suspend_late") > > Fixes: 28b6fd6e3779 ("PM / sleep: Asynchronous threads for suspend_noirq") > > Reported-by: Jeffy Chen <jeffy.chen@...k-chips.com> > > Signed-off-by: Brian Norris <briannorris@...omium.org> > > If the patch is otherwise acceptable, feel free to make the above edits. > Or I can fix them up if I send v2. Please fix up, we should never have to hand-edit a changelog text...
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