[PATCH v8 1/2] drm/gem: Properly annotate WW context on drm_gem_lock_reservations() error

Dmitry Osipenko
2022-07-01T09:04:03Z

Use ww_acquire_fini() in the error code paths. Otherwise lockdep
thinks that lock is held when lock's memory is freed after the
drm_gem_lock_reservations() error. The ww_acquire_context needs to be
annotated as "released", which fixes the noisy "WARNING: held lock freed!"
splat of VirtIO-GPU driver with CONFIG_DEBUG_MUTEXES=y and enabled lockdep.

Cc: stable@vger.kernel.org
Fixes: 7edc3e3b975b5 ("drm: Add helpers for locking an array of BO reservations.")
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
---
drivers/gpu/drm/drm_gem.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index eb0c2d041f13..86d670c71286 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -1226,7 +1226,7 @@ drm_gem_lock_reservations(struct drm_gem_object **objs, int count,
ret = dma_resv_lock_slow_interruptible(obj->resv,
acquire_ctx);
if (ret) {
- ww_acquire_done(acquire_ctx);
+ ww_acquire_fini(acquire_ctx);
return ret;
}
}
@@ -1251,7 +1251,7 @@ drm_gem_lock_reservations(struct drm_gem_object **objs, int count,
goto retry;
}

- ww_acquire_done(acquire_ctx);
+ ww_acquire_fini(acquire_ctx);
return ret;
}
}
--
2.36.1