On 27/02/2020 08:57, Chris Wilson wrote:
Pull the final atomic_dec of vm->open (marking the vm as closed)
underneath the same vm->mutex as used to close it. This is required to
correctly serialise with attempting to reuse the vma as the vm is closed
by a second thread.
References: 00de702c6c6f ("drm/i915: Check that the vma hasn't been closed before we insert it")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_gtt.c | 5 ++++-
drivers/gpu/drm/i915/gt/intel_gtt.h | 3 +--
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.c b/drivers/gpu/drm/i915/gt/intel_gtt.c
index bb9a6e638175..dfb1be050cca 100644
--- a/drivers/gpu/drm/i915/gt/intel_gtt.c
+++ b/drivers/gpu/drm/i915/gt/intel_gtt.c
@@ -171,7 +171,9 @@ void __i915_vm_close(struct i915_address_space *vm)
{
struct i915_vma *vma, *vn;
- mutex_lock(&vm->mutex);
+ if (!atomic_dec_and_mutex_lock(&vm->open, &vm->mutex))
+ return;
+
list_for_each_entry_safe(vma, vn, &vm->bound_list, vm_link) {
struct drm_i915_gem_object *obj = vma->obj;
@@ -186,6 +188,7 @@ void __i915_vm_close(struct i915_address_space *vm)
i915_gem_object_put(obj);
}
GEM_BUG_ON(!list_empty(&vm->bound_list));
+
mutex_unlock(&vm->mutex);
}
diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.h b/drivers/gpu/drm/i915/gt/intel_gtt.h
index 23004445806a..eac38c682ef4 100644
--- a/drivers/gpu/drm/i915/gt/intel_gtt.h
+++ b/drivers/gpu/drm/i915/gt/intel_gtt.h
@@ -429,8 +429,7 @@ static inline void
i915_vm_close(struct i915_address_space *vm)
{
GEM_BUG_ON(!atomic_read(&vm->open));
- if (atomic_dec_and_test(&vm->open))
- __i915_vm_close(vm);
+ __i915_vm_close(vm);
i915_vm_put(vm);
}
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Regards,
Tvrtko
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