diff options
| author | Thomas Hellstrom | 2010-11-17 12:28:28 +0000 |
|---|---|---|
| committer | Dave Airlie | 2010-11-22 13:25:17 +1000 |
| commit | 96726fe50feae74812a2ccf5d5da23cb01c0a413 (patch) | |
| tree | 1c5cb041b88e33ae5d10cb9292852cc5ee5fb24b | |
| parent | 68c4fa31aa52765314b4285a7835368ea35b509c (diff) | |
drm/ttm: Don't deadlock on recursive multi-bo reservations
Add an aid for the driver to detect deadlocks on multi-bo reservations
Update documentation.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jerome Glisse <j.glisse@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
| -rw-r--r-- | drivers/gpu/drm/ttm/ttm_bo.c | 15 | ||||
| -rw-r--r-- | include/drm/ttm/ttm_bo_driver.h | 25 |
2 files changed, 34 insertions, 6 deletions
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index 9ef893d5da88..5d8750830dc3 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -223,9 +223,18 @@ int ttm_bo_reserve_locked(struct ttm_buffer_object *bo, /** * Deadlock avoidance for multi-bo reserving. */ - if (use_sequence && bo->seq_valid && - (sequence - bo->val_seq < (1 << 31))) { - return -EAGAIN; + if (use_sequence && bo->seq_valid) { + /** + * We've already reserved this one. + */ + if (unlikely(sequence == bo->val_seq)) + return -EDEADLK; + /** + * Already reserved by a thread that will not back + * off for us. We need to back off. + */ + if (unlikely(sequence - bo->val_seq < (1 << 31))) + return -EAGAIN; } if (no_wait) diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h index 95068e6024db..1e25a40c688e 100644 --- a/include/drm/ttm/ttm_bo_driver.h +++ b/include/drm/ttm/ttm_bo_driver.h @@ -859,6 +859,9 @@ extern void ttm_bo_unmap_virtual(struct ttm_buffer_object *bo); * try again. (only if use_sequence == 1). * -ERESTARTSYS: A wait for the buffer to become unreserved was interrupted by * a signal. Release all buffer reservations and return to user-space. + * -EBUSY: The function needed to sleep, but @no_wait was true + * -EDEADLK: Bo already reserved using @sequence. This error code will only + * be returned if @use_sequence is set to true. */ extern int ttm_bo_reserve(struct ttm_buffer_object *bo, bool interruptible, @@ -868,11 +871,27 @@ extern int ttm_bo_reserve(struct ttm_buffer_object *bo, /** * ttm_bo_reserve_locked: * - * Similar to ttm_bo_reserve, but must be called with the glob::lru_lock - * spinlock held, and will not remove reserved buffers from the lru lists. + * @bo: A pointer to a struct ttm_buffer_object. + * @interruptible: Sleep interruptible if waiting. + * @no_wait: Don't sleep while trying to reserve, rather return -EBUSY. + * @use_sequence: If @bo is already reserved, Only sleep waiting for + * it to become unreserved if @sequence < (@bo)->sequence. + * + * Must be called with struct ttm_bo_global::lru_lock held, + * and will not remove reserved buffers from the lru lists. * The function may release the LRU spinlock if it needs to sleep. + * Otherwise identical to ttm_bo_reserve. + * + * Returns: + * -EAGAIN: The reservation may cause a deadlock. + * Release all buffer reservations, wait for @bo to become unreserved and + * try again. (only if use_sequence == 1). + * -ERESTARTSYS: A wait for the buffer to become unreserved was interrupted by + * a signal. Release all buffer reservations and return to user-space. + * -EBUSY: The function needed to sleep, but @no_wait was true + * -EDEADLK: Bo already reserved using @sequence. This error code will only + * be returned if @use_sequence is set to true. */ - extern int ttm_bo_reserve_locked(struct ttm_buffer_object *bo, bool interruptible, bool no_wait, bool use_sequence, |