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| author | Thomas Hellstrom <thellstrom@vmware.com> | 2010-11-17 12:28:28 +0000 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2010-11-22 13:25:17 +1000 |
| commit | 96726fe50feae74812a2ccf5d5da23cb01c0a413 (patch) | |
| tree | 1c5cb041b88e33ae5d10cb9292852cc5ee5fb24b /drivers/gpu/drm/ttm/ttm_bo.c | |
| parent | 68c4fa31aa52765314b4285a7835368ea35b509c (diff) | |
| download | lwn-96726fe50feae74812a2ccf5d5da23cb01c0a413.tar.gz lwn-96726fe50feae74812a2ccf5d5da23cb01c0a413.zip | |
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>
Diffstat (limited to 'drivers/gpu/drm/ttm/ttm_bo.c')
| -rw-r--r-- | drivers/gpu/drm/ttm/ttm_bo.c | 15 |
1 files changed, 12 insertions, 3 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) |