drm/xe: Take a reference in xe_exec_queue_last_fence_get()

Take a reference in xe_exec_queue_last_fence_get(). Also fix a reference
counting underflow bug VM bind and unbind.

Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240201004849.2219558-2-matthew.brost@intel.com
(cherry picked from commit a856b67a84169e065ebbeee50258936b1eacc9eb)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c b/drivers/gpu/drm/xe/xe_exec_queue.c
index bcfc4127c7c59f0fffc8e40df70a5b1c8222495f..254b1d3af4cb56888700f82b2a6b8fa3436e1a2a 100644 (file)
--- a/drivers/gpu/drm/xe/xe_exec_queue.c
+++ b/drivers/gpu/drm/xe/xe_exec_queue.c
@@ -926,20 +926,24 @@ void xe_exec_queue_last_fence_put_unlocked(struct xe_exec_queue *q)
  * @q: The exec queue
  * @vm: The VM the engine does a bind or exec for
  *
- * Get last fence, does not take a ref
+ * Get last fence, takes a ref
  *
  * Returns: last fence if not signaled, dma fence stub if signaled
  */
 struct dma_fence *xe_exec_queue_last_fence_get(struct xe_exec_queue *q,
                                               struct xe_vm *vm)
 {
+       struct dma_fence *fence;
+
        xe_exec_queue_last_fence_lockdep_assert(q, vm);
 
        if (q->last_fence &&
            test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &q->last_fence->flags))
                xe_exec_queue_last_fence_put(q, vm);
 
-       return q->last_fence ? q->last_fence : dma_fence_get_stub();
+       fence = q->last_fence ? q->last_fence : dma_fence_get_stub();
+       dma_fence_get(fence);
+       return fence;
 }
 
 /**

diff --git a/drivers/gpu/drm/xe/xe_migrate.c b/drivers/gpu/drm/xe/xe_migrate.c
index 5c6c5462425217c9301560a626d67ec7386bd418..0cc31837ef26bc65123d431326fd4f79bee68010 100644 (file)
--- a/drivers/gpu/drm/xe/xe_migrate.c
+++ b/drivers/gpu/drm/xe/xe_migrate.c
@@ -1204,8 +1204,11 @@ static bool no_in_syncs(struct xe_vm *vm, struct xe_exec_queue *q,
        }
        if (q) {
                fence = xe_exec_queue_last_fence_get(q, vm);
-               if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+               if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
+                       dma_fence_put(fence);
                        return false;
+               }
+               dma_fence_put(fence);
        }
 
        return true;

diff --git a/drivers/gpu/drm/xe/xe_sched_job.c b/drivers/gpu/drm/xe/xe_sched_job.c
index 01106a1156ad82ab30378b29abf3f18d55b64fe3..4e2ccad0e52fabaf43ea26ddc1dd86f2294662a1 100644 (file)
--- a/drivers/gpu/drm/xe/xe_sched_job.c
+++ b/drivers/gpu/drm/xe/xe_sched_job.c
@@ -274,7 +274,6 @@ int xe_sched_job_last_fence_add_dep(struct xe_sched_job *job, struct xe_vm *vm)
        struct dma_fence *fence;
 
        fence = xe_exec_queue_last_fence_get(job->q, vm);
-       dma_fence_get(fence);
 
        return drm_sched_job_add_dependency(&job->drm, fence);
 }

diff --git a/drivers/gpu/drm/xe/xe_sync.c b/drivers/gpu/drm/xe/xe_sync.c
index e4c220cf9115e9d52fc7b1e9440e0e44ba247c46..aab92bee1d7cf2ff52ec07befe0dcc220325a649 100644 (file)
--- a/drivers/gpu/drm/xe/xe_sync.c
+++ b/drivers/gpu/drm/xe/xe_sync.c
@@ -307,7 +307,6 @@ xe_sync_in_fence_get(struct xe_sync_entry *sync, int num_sync,
        /* Easy case... */
        if (!num_in_fence) {
                fence = xe_exec_queue_last_fence_get(q, vm);
-               dma_fence_get(fence);
                return fence;
        }
 
@@ -322,7 +321,6 @@ xe_sync_in_fence_get(struct xe_sync_entry *sync, int num_sync,
                }
        }
        fences[current_fence++] = xe_exec_queue_last_fence_get(q, vm);
-       dma_fence_get(fences[current_fence - 1]);
        cf = dma_fence_array_create(num_in_fence, fences,
                                    vm->composite_fence_ctx,
                                    vm->composite_fence_seqno++,

diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
index d45cbf75d2037100fc096bd18c8bacd15561d252..96b1833c0e8c6fd896788b882862c531b863f45b 100644 (file)
--- a/drivers/gpu/drm/xe/xe_vm.c
+++ b/drivers/gpu/drm/xe/xe_vm.c
@@ -1984,6 +1984,7 @@ static int xe_vm_prefetch(struct xe_vm *vm, struct xe_vma *vma,
                                        xe_exec_queue_last_fence_get(wait_exec_queue, vm);
 
                                xe_sync_entry_signal(&syncs[i], NULL, fence);
+                               dma_fence_put(fence);
                        }
                }