[PATCH v2 5/7] xfree86: Fix race condition failure opening drm.

[Bryce Harrington <bryce@canonical.com>]

If other processes have had drm open previously, xserver may attempt to
open the device too early and fail, with xserver error exit "Cannot
run in framebuffer mode" or Xorg.0.log messages about "setversion 1.4
failed".

In this situation, we're receiving back -EACCES from libdrm.  To address
this we need to re-set ourselves as the drm master, and keep trying to
set the interface until it works (or until we give up).

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

Signed-off-by: Bryce Harrington <bryce@canonical.com>
---
 hw/xfree86/os-support/linux/lnx_platform.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/xfree86/os-support/linux/lnx_platform.c b/hw/xfree86/os-support/linux/lnx_platform.c
index 4094866..bb76d90 100644
--- a/hw/xfree86/os-support/linux/lnx_platform.c
+++ b/hw/xfree86/os-support/linux/lnx_platform.c
@@ -43,8 +43,14 @@ get_drm_info(struct OdevAttributes *attribs, char *path)
 	    if (tries > 1)
 		LogMessage(X_INFO, "setversion 1.4 succeeded on try #%d\n", tries);
 	    break;
+	} if (err != -EACCES) {
+	    break;
 	}
+
 	usleep(1000);
+
+	if (!drmSetMaster(fd))
+	    LogMessage(X_INFO, "drmSetMaster succeeded\n");
     }
     if (err) {
         ErrorF("setversion 1.4 failed: %s\n", strerror(-err));
-- 
1.7.9.5