From: Colin Cross <ccross@android.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: Zoran Markovic <zoran.markovic@linaro.org>,
lkml <linux-kernel@vger.kernel.org>,
Linux PM list <linux-pm@vger.kernel.org>,
Benoit Goby <benoit@android.com>,
Android Kernel Team <kernel-team@android.com>,
Todd Poynor <toddpoynor@google.com>, San Mehat <san@google.com>,
John Stultz <john.stultz@linaro.org>,
"Rafael J. Wysocki" <rjw@sisk.pl>,
Len Brown <len.brown@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [RFC PATCH] drivers: power: Add watchdog timer to catch drivers which lockup during suspend.
Date: Thu, 2 May 2013 11:25:12 -0700 [thread overview]
Message-ID: <CAMbhsRSdk-z-67BEEd=zbWLR6=WXjpCk1uJky2ZEONS7FLcmGw@mail.gmail.com> (raw)
In-Reply-To: <20130502123033.GC22618@amd.pavel.ucw.cz>
On Thu, May 2, 2013 at 5:30 AM, Pavel Machek <pavel@ucw.cz> wrote:
> Hi!
>
>> >> > do BUG which
>> >> > dumps stack of current task
>> >> > kills current task
>> >> >
>> >> > Current task may very well be idle task; in such case you kill the
>> >> > machine. Sounds like you should be doing something else, like kill -9
>> >> > instead of BUG()?
>> >>
>> >> Not much else you can do, you are stuck part way into suspend with a
>> >> driver's suspend callback half executed. All userspace tasks are
>> >> frozen, and the suspend task is blocked indefinitely.
>> >
>> > Yes, there's better option. Attempt killing the [a]suspend task,
>> > instead of killing the current task.
>>
>> That will leave you in a completely undefined state. If you just kill
>> the task, you are likely to kill the synchronous suspend task, which
>> is the task that would resume your drivers and unfreeze tasks. That
>> will leave you with no userspace tasks running, and much of your
>> hardware suspended. How is that a useful result? If you somehow
>
> So instead you kill random task? (BUG() from timer kills pretty much
> random task, right?)
>
> If you want to do panic(), do panic().
At least on ARM a BUG() in an interrupt or softirq always results in a
panic, but this can be switched to directly call panic.
prev parent reply other threads:[~2013-05-02 18:25 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-30 22:28 [RFC PATCH] drivers: power: Add watchdog timer to catch drivers which lockup during suspend Zoran Markovic
2013-04-30 22:28 ` [RFC PATCH] power: Add option to log time spent in suspend Zoran Markovic
2013-05-01 0:29 ` Pavel Machek
2013-05-01 3:29 ` Colin Cross
2013-05-02 12:27 ` Pavel Machek
2013-05-02 18:29 ` Colin Cross
2013-05-02 18:58 ` John Stultz
2013-05-02 19:11 ` Colin Cross
2013-04-30 23:30 ` [RFC PATCH] drivers: power: Add watchdog timer to catch drivers which lockup during suspend Greg Kroah-Hartman
2013-05-01 3:36 ` Colin Cross
2013-05-01 4:17 ` Greg Kroah-Hartman
2013-05-01 4:39 ` Colin Cross
[not found] ` <CAK7N6voYXxJKWDwSj5T9Y2fKK+Y5JqN9Wm8Qoffi9N7nRnsYhw@mail.gmail.com>
2013-05-01 5:14 ` Colin Cross
2013-05-01 0:30 ` Pavel Machek
2013-05-01 3:39 ` Colin Cross
2013-05-01 10:56 ` Pavel Machek
2013-05-01 16:10 ` Colin Cross
2013-05-01 16:24 ` Greg Kroah-Hartman
2013-05-02 12:30 ` Pavel Machek
2013-05-02 18:25 ` Colin Cross [this message]
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