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 ?
Cheers, Jerome
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.
Dave.
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.
Dave.
dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel
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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Thomas Hellstrom