diff options
| author | Matthew Auld <matthew.auld@intel.com> | 2023-07-19 11:38:12 +0300 |
|---|---|---|
| committer | Rodrigo Vivi <rodrigo.vivi@intel.com> | 2023-12-21 19:37:36 +0300 |
| commit | e3d2309250d49e4558b0abe95924b18f74995607 (patch) | |
| tree | 6e21f3a5aca6240848404fbcfc2fb5779a3f5568 /drivers/gpu/drm/xe/xe_device.c | |
| parent | 7d623575a34539c0302a3ed3ec7321efcb281e37 (diff) | |
| download | linux-e3d2309250d49e4558b0abe95924b18f74995607.tar.xz | |
drm/xe: add lockdep annotation for xe_device_mem_access_get()
The atomics here might hide potential issues, also rpm core is not
holding any lock when calling our rpm resume callback, so add a dummy lock
with the idea that xe_pm_runtime_resume() is eventually going to be
called when we are holding it. This only needs to happen once and then
lockdep can validate all callers and their locks.
v2: (Thomas Hellström)
- Prefer static lockdep_map instead of full blown mutex.
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Acked-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Diffstat (limited to 'drivers/gpu/drm/xe/xe_device.c')
| -rw-r--r-- | drivers/gpu/drm/xe/xe_device.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c index 47401bb49958..b1f36c986f0d 100644 --- a/drivers/gpu/drm/xe/xe_device.c +++ b/drivers/gpu/drm/xe/xe_device.c @@ -34,6 +34,12 @@ #include "xe_vm_madvise.h" #include "xe_wait_user_fence.h" +#ifdef CONFIG_LOCKDEP +static struct lockdep_map xe_device_mem_access_lockdep_map = { + .name = "xe_device_mem_access_lockdep_map" +}; +#endif + static int xe_file_open(struct drm_device *dev, struct drm_file *file) { struct xe_file *xef; @@ -410,10 +416,28 @@ void xe_device_mem_access_get(struct xe_device *xe) if (xe_pm_read_callback_task(xe) == current) return; + /* + * Since the resume here is synchronous it can be quite easy to deadlock + * if we are not careful. Also in practice it might be quite timing + * sensitive to ever see the 0 -> 1 transition with the callers locks + * held, so deadlocks might exist but are hard for lockdep to ever see. + * With this in mind, help lockdep learn about the potentially scary + * stuff that can happen inside the runtime_resume callback by acquiring + * a dummy lock (it doesn't protect anything and gets compiled out on + * non-debug builds). Lockdep then only needs to see the + * mem_access_lockdep_map -> runtime_resume callback once, and then can + * hopefully validate all the (callers_locks) -> mem_access_lockdep_map. + * For example if the (callers_locks) are ever grabbed in the + * runtime_resume callback, lockdep should give us a nice splat. + */ + lock_map_acquire(&xe_device_mem_access_lockdep_map); + xe_pm_runtime_get(xe); ref = atomic_inc_return(&xe->mem_access.ref); XE_WARN_ON(ref == S32_MAX); + + lock_map_release(&xe_device_mem_access_lockdep_map); } void xe_device_mem_access_put(struct xe_device *xe) |