From: Thomas Hellstrom <thomas@shipmail.org>
To: dri-devel@lists.freedesktop.org
Subject: Re: GEM - radeon cs ioctl deadlock
Date: Mon, 18 Oct 2010 17:16:07 +0200 [thread overview]
Message-ID: <4CBC64B7.7000200@shipmail.org> (raw)
In-Reply-To: <1287020839.812.2.camel@nisroch>
On 10/14/2010 03:47 AM, Ben Skeggs wrote:
> On Thu, 2010-10-14 at 08:14 +1000, Dave Airlie wrote:
>
>> On Wed, 2010-10-13 at 17:57 -0400, Jerome Glisse wrote:
>>
>>> So we are facing a deadlock with the radeon cs ioctl. When a buffer is given
>>> a name (with flink) we could endup with 2 handle pointing to the same
>>> object (flink object and open it from same file descriptor). Would it be ok
>>> if i change gem open to first look if we already have an handle for the
>>> object and to use that handle instead of creating a new one ? Or could
>>> this break intel driver ?
>>>
>> I think r300g worked around this already, maybe we should just avoid
>> doing it from userspace if possible.
>>
> We had this in nouveau at some point. In the end, I prevented the
> deadlock from occuring by checking that a process doesn't reserve the
> same buffer twice (we store file_priv in a reserved_by field in the bo
> as we reserve the buffers), and then just fixed userspace.
>
> Ben.
>
>>
Hi, Ben,
Without knowing the exact details, that sounds a little dangerous? It
would be better to use a process identifier rather than a file
identifier since multiple threads in a single client can and should use
the same file descriptor.
/Thomas
>> Dave.
>>
>>
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/dri-devel
>>
>
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>
prev parent reply other threads:[~2010-10-18 15:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-13 21:57 GEM - radeon cs ioctl deadlock Jerome Glisse
2010-10-13 22:14 ` Dave Airlie
2010-10-14 1:47 ` Ben Skeggs
2010-10-18 15:16 ` Thomas Hellstrom [this message]
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