Merge branch 'drm-intel-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ickle...

[linux-beck.git] / drivers / gpu / drm / ttm / ttm_bo.c

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 3ca77dc03915017e78d0e7f7e8e479d9f279fc56..148a322d8f5d7c45d0487351635f89eb9a9a0949 100644 (file)
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -224,6 +224,9 @@ int ttm_bo_reserve_locked(struct ttm_buffer_object *bo,
        int ret;
 
        while (unlikely(atomic_cmpxchg(&bo->reserved, 0, 1) != 0)) {
+               /**
+                * Deadlock avoidance for multi-bo reserving.
+                */
                if (use_sequence && bo->seq_valid &&
                        (sequence - bo->val_seq < (1 << 31))) {
                        return -EAGAIN;
@@ -241,6 +244,14 @@ int ttm_bo_reserve_locked(struct ttm_buffer_object *bo,
        }
 
        if (use_sequence) {
+               /**
+                * Wake up waiters that may need to recheck for deadlock,
+                * if we decreased the sequence number.
+                */
+               if (unlikely((bo->val_seq - sequence < (1 << 31))
+                            || !bo->seq_valid))
+                       wake_up_all(&bo->event_queue);
+
                bo->val_seq = sequence;
                bo->seq_valid = true;
        } else {