drm/amdgpu: partial revert "remove ctx->lock" v2

This reverts commit 461fa7b.

We are missing some inter dependencies here so re-introduce the lock
until we have figured out what's missing. Just drop/retake it while
adding dependencies.

v2: still drop the lock while adding dependencies

Signed-off-by: Christian König <christian.koenig@amd.com>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> (v1)
Fixes: 461fa7b ("drm/amdgpu: remove ctx->lock")
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220419110633.166236-1-christian.koenig@amd.com

drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c

@@ -128,6 +128,8 @@ static int amdgpu_cs_parser_init(struct amdgpu_cs_parser *p, union drm_amdgpu_cs
 		goto free_chunk;
 	}
 
+	mutex_lock(&p->ctx->lock);
+
 	/* skip guilty context job */
 	if (atomic_read(&p->ctx->guilty) == 1) {
 		ret = -ECANCELED;
@@ -709,6 +711,7 @@ static void amdgpu_cs_parser_fini(struct amdgpu_cs_parser *parser, int error,
 	dma_fence_put(parser->fence);
 
 	if (parser->ctx) {
+		mutex_unlock(&parser->ctx->lock);
 		amdgpu_ctx_put(parser->ctx);
 	}
 	if (parser->bo_list)
@@ -1157,6 +1160,9 @@ static int amdgpu_cs_dependencies(struct amdgpu_device *adev,
 {
 	int i, r;
 
+	/* TODO: Investigate why we still need the context lock */
+	mutex_unlock(&p->ctx->lock);
+
 	for (i = 0; i < p->nchunks; ++i) {
 		struct amdgpu_cs_chunk *chunk;
 
@@ -1167,32 +1173,34 @@ static int amdgpu_cs_dependencies(struct amdgpu_device *adev,
 		case AMDGPU_CHUNK_ID_SCHEDULED_DEPENDENCIES:
 			r = amdgpu_cs_process_fence_dep(p, chunk);
 			if (r)
-				return r;
+				goto out;
 			break;
 		case AMDGPU_CHUNK_ID_SYNCOBJ_IN:
 			r = amdgpu_cs_process_syncobj_in_dep(p, chunk);
 			if (r)
-				return r;
+				goto out;
 			break;
 		case AMDGPU_CHUNK_ID_SYNCOBJ_OUT:
 			r = amdgpu_cs_process_syncobj_out_dep(p, chunk);
 			if (r)
-				return r;
+				goto out;
 			break;
 		case AMDGPU_CHUNK_ID_SYNCOBJ_TIMELINE_WAIT:
 			r = amdgpu_cs_process_syncobj_timeline_in_dep(p, chunk);
 			if (r)
-				return r;
+				goto out;
 			break;
 		case AMDGPU_CHUNK_ID_SYNCOBJ_TIMELINE_SIGNAL:
 			r = amdgpu_cs_process_syncobj_timeline_out_dep(p, chunk);
 			if (r)
-				return r;
+				goto out;
 			break;
 		}
 	}
 
-	return 0;
+out:
+	mutex_lock(&p->ctx->lock);
+	return r;
 }
 
 static void amdgpu_cs_post_dependencies(struct amdgpu_cs_parser *p)
@@ -1368,6 +1376,7 @@ int amdgpu_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
 		goto out;
 
 	r = amdgpu_cs_submit(&parser, cs);
+
 out:
 	amdgpu_cs_parser_fini(&parser, r, reserved_buffers);
 

drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c

@@ -237,6 +237,7 @@ static int amdgpu_ctx_init(struct amdgpu_device *adev,
 
 	kref_init(&ctx->refcount);
 	spin_lock_init(&ctx->ring_lock);
+	mutex_init(&ctx->lock);
 
 	ctx->reset_counter = atomic_read(&adev->gpu_reset_counter);
 	ctx->reset_counter_query = ctx->reset_counter;
@@ -357,6 +358,7 @@ static void amdgpu_ctx_fini(struct kref *ref)
 		drm_dev_exit(idx);
 	}
 
+	mutex_destroy(&ctx->lock);
 	kfree(ctx);
 }
 

drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h

@@ -49,6 +49,7 @@ struct amdgpu_ctx {
 	bool				preamble_presented;
 	int32_t				init_priority;
 	int32_t				override_priority;
+	struct mutex			lock;
 	atomic_t			guilty;
 	unsigned long			ras_counter_ce;
 	unsigned long			ras_counter_ue;