9ea8d05932
Hugh found an error path where we were attempting to unref a bo without holding the struct mutex: [drm:intel_init_clock_gating] *ERROR* failed to pin power context: -16 ------------[ cut here ]------------ WARNING: at drivers/gpu/drm/drm_gem.c:438 drm_gem_object_free+0x20/0x5e() Hardware name: ESPRIMO Mobile V5505 Modules linked in: snd_pcm_oss snd_mixer_oss snd_seq snd_seq_device Pid: 3793, comm: s2ram Not tainted 2.6.33-rc2 #4 Call Trace: [<7815298e>] warn_slowpath_common+0x59/0x6b [<781529b3>] warn_slowpath_null+0x13/0x18 [<78317c1a>] ? drm_gem_object_free+0x20/0x5e [<78317c1a>] drm_gem_object_free+0x20/0x5e [<78317bfa>] ? drm_gem_object_free+0x0/0x5e [<7829df11>] kref_put+0x38/0x45 [<7833a5f0>] intel_init_clock_gating+0x232/0x271 [<78317bfa>] ? drm_gem_object_free+0x0/0x5e [<7832c307>] i915_restore_state+0x21a/0x2b3 [<7832379d>] i915_resume+0x3c/0xbb [<78174fe5>] ? trace_hardirqs_on_caller+0xfc/0x123 [<7831c756>] ? drm_class_resume+0x0/0x3e [<7831c78d>] drm_class_resume+0x37/0x3e [<78351e0a>] legacy_resume+0x1e/0x51 [<78351ece>] device_resume+0x91/0xab [<7831c756>] ? drm_class_resume+0x0/0x3e [<78352226>] dpm_resume+0x58/0x10f [<783522fb>] dpm_resume_end+0x1e/0x2c [<78180f80>] suspend_devices_and_enter+0x61/0x84 [<78180ff8>] enter_state+0x55/0x83 [<7818091c>] state_store+0x94/0xaa [<7829d09e>] kobj_attr_store+0x1e/0x23 [<782098e0>] sysfs_write_file+0x66/0x99 [<781cd2f0>] vfs_write+0x8a/0x108 [<781cd408>] sys_write+0x3c/0x63 [<78125c10>] sysenter_do_call+0x12/0x36 ---[ end trace a343537f29950fda ]--- It is in fact slightly more insiduous that first appears since we are attempting to not just free the object without the lock, but are trying to do the whole bo manipulation without holding the lock. Reported-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: stable@kernel.org Signed-off-by: Eric Anholt <eric@anholt.net>
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* For the very latest on DRI development, please see: *
* http://dri.freedesktop.org/ *
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The Direct Rendering Manager (drm) is a device-independent kernel-level
device driver that provides support for the XFree86 Direct Rendering
Infrastructure (DRI).
The DRM supports the Direct Rendering Infrastructure (DRI) in four major
ways:
1. The DRM provides synchronized access to the graphics hardware via
the use of an optimized two-tiered lock.
2. The DRM enforces the DRI security policy for access to the graphics
hardware by only allowing authenticated X11 clients access to
restricted regions of memory.
3. The DRM provides a generic DMA engine, complete with multiple
queues and the ability to detect the need for an OpenGL context
switch.
4. The DRM is extensible via the use of small device-specific modules
that rely extensively on the API exported by the DRM module.
Documentation on the DRI is available from:
http://dri.freedesktop.org/wiki/Documentation
http://sourceforge.net/project/showfiles.php?group_id=387
http://dri.sourceforge.net/doc/
For specific information about kernel-level support, see:
The Direct Rendering Manager, Kernel Support for the Direct Rendering
Infrastructure
http://dri.sourceforge.net/doc/drm_low_level.html
Hardware Locking for the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/hardware_locking_low_level.html
A Security Analysis of the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/security_low_level.html