[Intel-gfx] [PATCH v2 0/7] xfree86: Handle drm race condition

[Bryce Harrington]

Update:  Squashes a couple commits to avoid potential hang if
git bisecting.  No other changes from v1.

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When starting up (on Ubuntu), X can hit an error trying to set the
version on the drm device.  We believe this is a race with plymouth (or
the kernel), since adding some delay to the boot results in a
functioning session for affected users.

So far we have not found a reliable way to reproduce the bug
synthetically.  It appears to affect users on fast booting hardware
(e.g. SSDs) when using the Intel graphics driver.

We have not root-caused the bug yet.  Currently we suspect the actual
breakage is underneath X (plymouth/lightdm/kernel), and are still
experimenting.  However, this patch does seem to improve things for
users, so it or parts of it may be worth your consideration for
inclusion in xserver.

I'm including the patch broken down into easily pickable chunks.  Note
the final patch in the series is highly optional; it handles EAGAIN
being passed from the ioctl - which looks impossible to happen in
practice.

https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/982889


Bryce Harrington (7):
  xfree86: (Cleanup) Close fd if drm interface 1.4 could not be set.
  xfree86: Track error code and add label for error handling.
  xfree86: Provide more details on failure
  xfree86: Keep trying to set interface on drm for 2 seconds.
  xfree86: Fix race condition failure opening drm.
  xfree86: Be verbose if waiting on opening the drm device
  xfree86: Also handle EAGAIN errors from drmSetInterfaceVersion().

 hw/xfree86/os-support/linux/lnx_platform.c |   43 ++++++++++++++++++++++------
 1 file changed, 35 insertions(+), 8 deletions(-)

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1.7.9.5