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c21f11d182
In mutex_init() lockdep identifies a lock by defining a special static
key for each lock class. However if we wrap the macro in a function,
like in drmm_mutex_init(), we end up generating:
int drmm_mutex_init(struct drm_device *dev, struct mutex *lock)
{
static struct lock_class_key __key;
__mutex_init((lock), "lock", &__key);
....
}
The static __key here is what lockdep uses to identify the lock class,
however since this is just a normal function the key here will be
created once, where all callers then use the same key. In effect the
mutex->depmap.key will be the same pointer for different
drmm_mutex_init() callers. This then results in impossible lockdep
splats since lockdep thinks completely unrelated locks are the same lock
class.
To fix this turn drmm_mutex_init() into a macro such that it generates a
different "static struct lock_class_key __key" for each invocation,
which looks to be inline with what mutex_init() wants.
v2:
- Revamp the commit message with clearer explanation of the issue.
- Rather export __drmm_mutex_release() than static inline.
Reported-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reported-by: Sarah Walker <sarah.walker@imgtec.com>
Fixes:
|
||
|---|---|---|
| .. | ||
| bridge | ||
| display | ||
| i2c | ||
| ttm | ||
| amd_asic_type.h | ||
| drm_accel.h | ||
| drm_aperture.h | ||
| drm_atomic_helper.h | ||
| drm_atomic_state_helper.h | ||
| drm_atomic_uapi.h | ||
| drm_atomic.h | ||
| drm_audio_component.h | ||
| drm_auth.h | ||
| drm_blend.h | ||
| drm_bridge_connector.h | ||
| drm_bridge.h | ||
| drm_buddy.h | ||
| drm_cache.h | ||
| drm_client.h | ||
| drm_color_mgmt.h | ||
| drm_connector.h | ||
| drm_crtc_helper.h | ||
| drm_crtc.h | ||
| drm_damage_helper.h | ||
| drm_debugfs_crc.h | ||
| drm_debugfs.h | ||
| drm_device.h | ||
| drm_displayid.h | ||
| drm_drv.h | ||
| drm_edid.h | ||
| drm_encoder_slave.h | ||
| drm_encoder.h | ||
| drm_fb_dma_helper.h | ||
| drm_fb_helper.h | ||
| drm_fbdev_dma.h | ||
| drm_fbdev_generic.h | ||
| drm_file.h | ||
| drm_fixed.h | ||
| drm_flip_work.h | ||
| drm_format_helper.h | ||
| drm_fourcc.h | ||
| drm_framebuffer.h | ||
| drm_gem_atomic_helper.h | ||
| drm_gem_dma_helper.h | ||
| drm_gem_framebuffer_helper.h | ||
| drm_gem_shmem_helper.h | ||
| drm_gem_ttm_helper.h | ||
| drm_gem_vram_helper.h | ||
| drm_gem.h | ||
| drm_ioctl.h | ||
| drm_kunit_helpers.h | ||
| drm_lease.h | ||
| drm_legacy.h | ||
| drm_managed.h | ||
| drm_mipi_dbi.h | ||
| drm_mipi_dsi.h | ||
| drm_mm.h | ||
| drm_mode_config.h | ||
| drm_mode_object.h | ||
| drm_modes.h | ||
| drm_modeset_helper_vtables.h | ||
| drm_modeset_helper.h | ||
| drm_modeset_lock.h | ||
| drm_module.h | ||
| drm_of.h | ||
| drm_panel.h | ||
| drm_pciids.h | ||
| drm_plane_helper.h | ||
| drm_plane.h | ||
| drm_prime.h | ||
| drm_print.h | ||
| drm_privacy_screen_consumer.h | ||
| drm_privacy_screen_driver.h | ||
| drm_privacy_screen_machine.h | ||
| drm_probe_helper.h | ||
| drm_property.h | ||
| drm_rect.h | ||
| drm_self_refresh_helper.h | ||
| drm_simple_kms_helper.h | ||
| drm_suballoc.h | ||
| drm_syncobj.h | ||
| drm_sysfs.h | ||
| drm_util.h | ||
| drm_utils.h | ||
| drm_vblank_work.h | ||
| drm_vblank.h | ||
| drm_vma_manager.h | ||
| drm_writeback.h | ||
| gma_drm.h | ||
| gpu_scheduler.h | ||
| gud.h | ||
| i915_component.h | ||
| i915_drm.h | ||
| i915_hdcp_interface.h | ||
| i915_pciids.h | ||
| i915_pxp_tee_interface.h | ||
| intel_lpe_audio.h | ||
| intel-gtt.h | ||
| spsc_queue.h | ||
| task_barrier.h | ||