From 96726fe50feae74812a2ccf5d5da23cb01c0a413 Mon Sep 17 00:00:00 2001 From: Thomas Hellstrom Date: Wed, 17 Nov 2010 12:28:28 +0000 Subject: 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 Reviewed-by: Jerome Glisse Signed-off-by: Dave Airlie --- include/drm/ttm/ttm_bo_driver.h | 25 ++++++++++++++++++++++--- 1 file changed, 22 insertions(+), 3 deletions(-) (limited to 'include/drm/ttm') 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, -- cgit v1.2.3-59-g8ed1b