diff options
| author | Rob Clark <robdclark@chromium.org> | 2025-06-29 13:13:22 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-08-20 18:30:33 +0200 |
| commit | 20406ace80ad27d338023b62e7c83e28e61bafaf (patch) | |
| tree | ecc72754e2dbfa9f3d7aff9cb616fe76a43d506f | |
| parent | 574fb734ac3d882ed03f776aba39a1788af615ec (diff) | |
drm/msm: use trylock for debugfs
[ Upstream commit 0a1ff88ec5b60b41ba830c5bf08b6cd8f45ab411 ]
This resolves a potential deadlock vs msm_gem_vm_close(). Otherwise for
_NO_SHARE buffers msm_gem_describe() could be trying to acquire the
shared vm resv, while already holding priv->obj_lock. But _vm_close()
might drop the last reference to a GEM obj while already holding the vm
resv, and msm_gem_free_object() needs to grab priv->obj_lock, a locking
inversion.
OTOH this is only for debugfs and it isn't critical if we undercount by
skipping a locked obj. So just use trylock() and move along if we can't
get the lock.
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
Tested-by: Antonino Maniscalco <antomani103@gmail.com>
Reviewed-by: Antonino Maniscalco <antomani103@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/661525/
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/gpu/drm/msm/msm_gem.c | 3 | ||||
| -rw-r--r-- | drivers/gpu/drm/msm/msm_gem.h | 6 |
2 files changed, 8 insertions, 1 deletions
diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c index ebc9ba66efb8..eeb3b65dd4d1 100644 --- a/drivers/gpu/drm/msm/msm_gem.c +++ b/drivers/gpu/drm/msm/msm_gem.c @@ -963,7 +963,8 @@ void msm_gem_describe(struct drm_gem_object *obj, struct seq_file *m, uint64_t off = drm_vma_node_start(&obj->vma_node); const char *madv; - msm_gem_lock(obj); + if (!msm_gem_trylock(obj)) + return; stats->all.count++; stats->all.size += obj->size; diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h index 85f0257e83da..748053f70ca7 100644 --- a/drivers/gpu/drm/msm/msm_gem.h +++ b/drivers/gpu/drm/msm/msm_gem.h @@ -188,6 +188,12 @@ msm_gem_lock(struct drm_gem_object *obj) dma_resv_lock(obj->resv, NULL); } +static inline bool __must_check +msm_gem_trylock(struct drm_gem_object *obj) +{ + return dma_resv_trylock(obj->resv); +} + static inline int msm_gem_lock_interruptible(struct drm_gem_object *obj) { |