Locking mutex in different orders just screams for
deadlocks, and some testing showed that it is actually
quite easy to trigger them.
Signed-off-by: Christian König <deathsim...@vodafone.de>
Cc: sta...@vger.kernel.org
---
drivers/gpu/drm/radeon/radeon_gart.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/radeon/radeon_gart.c
b/drivers/gpu/drm/radeon/radeon_gart.c
index 79db56e..59d4493 100644
--- a/drivers/gpu/drm/radeon/radeon_gart.c
+++ b/drivers/gpu/drm/radeon/radeon_gart.c
@@ -476,12 +476,18 @@ int radeon_vm_bo_add(struct radeon_device *rdev,
mutex_lock(&vm->mutex);
if (last_pfn > vm->last_pfn) {
- /* grow va space 32M by 32M */
- unsigned align = ((32 << 20) >> 12) - 1;
+ /* release mutex and lock in right order */
+ mutex_unlock(&vm->mutex);
radeon_mutex_lock(&rdev->cs_mutex);
- radeon_vm_unbind_locked(rdev, vm);
+ mutex_lock(&vm->mutex);
+ /* and check again */
+ if (last_pfn > vm->last_pfn) {
+ /* grow va space 32M by 32M */
+ unsigned align = ((32 << 20) >> 12) - 1;
+ radeon_vm_unbind_locked(rdev, vm);
+ vm->last_pfn = (last_pfn + align) & ~align;
+ }
radeon_mutex_unlock(&rdev->cs_mutex);
- vm->last_pfn = (last_pfn + align) & ~align;
}
head = &vm->va;
last_offset = 0;
@@ -595,8 +601,8 @@ int radeon_vm_bo_rmv(struct radeon_device *rdev,
if (bo_va == NULL)
return 0;
- mutex_lock(&vm->mutex);
radeon_mutex_lock(&rdev->cs_mutex);
+ mutex_lock(&vm->mutex);
radeon_vm_bo_update_pte(rdev, vm, bo, NULL);
radeon_mutex_unlock(&rdev->cs_mutex);
list_del(&bo_va->vm_list);
@@ -641,9 +647,8 @@ void radeon_vm_fini(struct radeon_device *rdev, struct
radeon_vm *vm)
struct radeon_bo_va *bo_va, *tmp;
int r;
- mutex_lock(&vm->mutex);
-
radeon_mutex_lock(&rdev->cs_mutex);
+ mutex_lock(&vm->mutex);
radeon_vm_unbind_locked(rdev, vm);
radeon_mutex_unlock(&rdev->cs_mutex);
--
1.7.9.5
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