[PATCH v2 14/22] drm/msm: Protect ring->submits with it's own lock

[Rob Clark]

From: Rob Clark <robdclark at chromium.org>

One less place to rely on dev->struct_mutex.

Signed-off-by: Rob Clark <robdclark at chromium.org>
Reviewed-by: Jordan Crouse <jcrouse at codeaurora.org>
---
 drivers/gpu/drm/msm/msm_gem_submit.c |  2 ++
 drivers/gpu/drm/msm/msm_gpu.c        | 37 ++++++++++++++++++++++------
 drivers/gpu/drm/msm/msm_ringbuffer.c |  1 +
 drivers/gpu/drm/msm/msm_ringbuffer.h |  6 +++++
 4 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
index 35b7d9d06850..a91c1b99db97 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -65,7 +65,9 @@ void msm_gem_submit_free(struct msm_gem_submit *submit)
 	unsigned i;
 
 	dma_fence_put(submit->fence);
+	spin_lock(&submit->ring->submit_lock);
 	list_del(&submit->node);
+	spin_unlock(&submit->ring->submit_lock);
 	put_pid(submit->pid);
 	msm_submitqueue_put(submit->queue);
 
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index e5b7c8a77c99..bb904e467b24 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -270,6 +270,7 @@ static void update_fences(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
 {
 	struct msm_gem_submit *submit;
 
+	spin_lock(&ring->submit_lock);
 	list_for_each_entry(submit, &ring->submits, node) {
 		if (submit->seqno > fence)
 			break;
@@ -277,6 +278,7 @@ static void update_fences(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
 		msm_update_fence(submit->ring->fctx,
 			submit->fence->seqno);
 	}
+	spin_unlock(&ring->submit_lock);
 }
 
 #ifdef CONFIG_DEV_COREDUMP
@@ -430,11 +432,14 @@ find_submit(struct msm_ringbuffer *ring, uint32_t fence)
 {
 	struct msm_gem_submit *submit;
 
-	WARN_ON(!mutex_is_locked(&ring->gpu->dev->struct_mutex));
-
-	list_for_each_entry(submit, &ring->submits, node)
-		if (submit->seqno == fence)
+	spin_lock(&ring->submit_lock);
+	list_for_each_entry(submit, &ring->submits, node) {
+		if (submit->seqno == fence) {
+			spin_unlock(&ring->submit_lock);
 			return submit;
+		}
+	}
+	spin_unlock(&ring->submit_lock);
 
 	return NULL;
 }
@@ -523,8 +528,10 @@ static void recover_worker(struct work_struct *work)
 		for (i = 0; i < gpu->nr_rings; i++) {
 			struct msm_ringbuffer *ring = gpu->rb[i];
 
+			spin_lock(&ring->submit_lock);
 			list_for_each_entry(submit, &ring->submits, node)
 				gpu->funcs->submit(gpu, submit);
+			spin_unlock(&ring->submit_lock);
 		}
 	}
 
@@ -711,7 +718,6 @@ static void retire_submit(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
 static void retire_submits(struct msm_gpu *gpu)
 {
 	struct drm_device *dev = gpu->dev;
-	struct msm_gem_submit *submit, *tmp;
 	int i;
 
 	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
@@ -720,9 +726,24 @@ static void retire_submits(struct msm_gpu *gpu)
 	for (i = 0; i < gpu->nr_rings; i++) {
 		struct msm_ringbuffer *ring = gpu->rb[i];
 
-		list_for_each_entry_safe(submit, tmp, &ring->submits, node) {
-			if (dma_fence_is_signaled(submit->fence))
+		while (true) {
+			struct msm_gem_submit *submit = NULL;
+
+			spin_lock(&ring->submit_lock);
+			submit = list_first_entry_or_null(&ring->submits,
+					struct msm_gem_submit, node);
+			spin_unlock(&ring->submit_lock);
+
+			/*
+			 * If no submit, we are done.  If submit->fence hasn't
+			 * been signalled, then later submits are not signalled
+			 * either, so we are also done.
+			 */
+			if (submit && dma_fence_is_signaled(submit->fence)) {
 				retire_submit(gpu, ring, submit);
+			} else {
+				break;
+			}
 		}
 	}
 }
@@ -765,7 +786,9 @@ void msm_gpu_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 
 	submit->seqno = ++ring->seqno;
 
+	spin_lock(&ring->submit_lock);
 	list_add_tail(&submit->node, &ring->submits);
+	spin_unlock(&ring->submit_lock);
 
 	msm_rd_dump_submit(priv->rd, submit, NULL);
 
diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.c b/drivers/gpu/drm/msm/msm_ringbuffer.c
index 1b6958e908dc..4d2a2a4abef8 100644
--- a/drivers/gpu/drm/msm/msm_ringbuffer.c
+++ b/drivers/gpu/drm/msm/msm_ringbuffer.c
@@ -46,6 +46,7 @@ struct msm_ringbuffer *msm_ringbuffer_new(struct msm_gpu *gpu, int id,
 	ring->memptrs_iova = memptrs_iova;
 
 	INIT_LIST_HEAD(&ring->submits);
+	spin_lock_init(&ring->submit_lock);
 	spin_lock_init(&ring->preempt_lock);
 
 	snprintf(name, sizeof(name), "gpu-ring-%d", ring->id);
diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.h b/drivers/gpu/drm/msm/msm_ringbuffer.h
index 4956d1bc5d0e..fe55d4a1aa16 100644
--- a/drivers/gpu/drm/msm/msm_ringbuffer.h
+++ b/drivers/gpu/drm/msm/msm_ringbuffer.h
@@ -39,7 +39,13 @@ struct msm_ringbuffer {
 	int id;
 	struct drm_gem_object *bo;
 	uint32_t *start, *end, *cur, *next;
+
+	/*
+	 * List of in-flight submits on this ring.  Protected by submit_lock.
+	 */
 	struct list_head submits;
+	spinlock_t submit_lock;
+
 	uint64_t iova;
 	uint32_t seqno;
 	uint32_t hangcheck_fence;
-- 
2.26.2