From: Qing Huang <qing.huang@oracle.com>
To: Shamir Rabinovitch <shamir.rabinovitch@oracle.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Grant Likely <grant.likely@linaro.org>,
Santosh Shilimkar <santosh.shilimkar@oracle.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] device probe: add self triggered delayed work request
Date: Tue, 9 Aug 2016 13:57:47 -0700 [thread overview]
Message-ID: <57AA43CB.5050209@oracle.com> (raw)
In-Reply-To: <20160809101122.GA30759@shamir-linux.uk.oracle.com>
On 08/09/2016 03:11 AM, Shamir Rabinovitch wrote:
> On Mon, Aug 08, 2016 at 05:10:05PM -0700, Qing Huang wrote:
>> Not sure if I understood your scenario. Why there is a deadlock here?
>>
> CPU0 | CPU1
> ---------------------------------------------------------------------------------------------
> driver_deferred_probe_add | driver_deferred_probe_trigger_wrapper
> mutex_lock(&deferred_probe_mutex) | driver_deferred_probe_trigger
> cancel_delayed_work(&deferred_probe_trigger_work) | mutex_lock(&deferred_probe_mutex)
> wait for "driver_deferred_probe_trigger_wrapper" | wait for "deferred_probe_mutex"
>
> is this possible scenario with this patch?
>
> if yes then CPU0 will wait for CPU1 to finish the delayed work whith
> mutex deferred_probe_mutex held while CPU1 will try to finish the
> delayed work and will wait for the same mutex forever.
CPU0 will not wait for "driver_deferred_probe_trigger_wrapper" to
finish, it simply puts the work request onto the queue and returns.
Qing
>
> it seems like dead lock scenario to me.
>
> please say if this scenario is possible.
>
> BR, Shamir Rabinovitch
next prev parent reply other threads:[~2016-08-09 20:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-08 10:42 [PATCH] device probe: add self triggered delayed work request Shamir Rabinovitch
2016-08-09 0:10 ` Qing Huang
2016-08-09 10:11 ` Shamir Rabinovitch
2016-08-09 20:57 ` Qing Huang [this message]
-- strict thread matches above, loose matches on Subject: below --
2016-07-30 5:39 Qing Huang
2016-08-08 20:44 ` Frank Rowand
2016-08-08 21:51 ` Qing Huang
2016-08-09 1:11 ` Frank Rowand
2016-08-09 1:15 ` Santosh Shilimkar
2016-08-09 7:16 ` Frank Rowand
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