From: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
To: Hans Verkuil <hverkuil@xs4all.nl>,
linux-media@vger.kernel.org, mchehab@osg.samsung.com,
hans.verkuil@cisco.com
Subject: Re: em38xx locking question
Date: Tue, 10 Mar 2015 10:29:53 -0300 [thread overview]
Message-ID: <54FEF1D1.3000909@vanguardiasur.com.ar> (raw)
In-Reply-To: <54FEF0E9.9070804@xs4all.nl>
On 03/10/2015 10:26 AM, Hans Verkuil wrote:
> On 03/10/2015 02:18 PM, Ezequiel Garcia wrote:
>> Mauro,
>>
>> Function drivers/media/usb/em28xx/em28xx-video.c:get_next_buf
>> (copy pasted below for reference) does not take the list spinlock,
>> yet it modifies the list. Is that correct?
>
> That looks wrong to me. You really need spinlocks here.
>
OK, second question then. Is there any way to guarantee the URBs irq handler
is *not* running, when vb2_ops are called (e.g. stop_streaming)?
Otherwise, given stop_streaming will return the current buffer to vb2
(dev->usb_ctl.vid_buf), I believe that will race against the irq handler,
which is processing it.
It seems that's currently racy as well.
--
Ezequiel Garcia, VanguardiaSur
www.vanguardiasur.com.ar
next prev parent reply other threads:[~2015-03-10 13:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-10 13:18 em38xx locking question Ezequiel Garcia
2015-03-10 13:26 ` Hans Verkuil
2015-03-10 13:29 ` Ezequiel Garcia [this message]
2015-03-10 13:46 ` Hans Verkuil
2015-03-10 14:06 ` Ezequiel Garcia
2015-03-10 14:16 ` Hans Verkuil
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