drm/amdgpu: remove ctx->lock

KMD reports a warning on holding a lock from drm_syncobj_find_fence,
when running amdgpu_test case “syncobj timeline test”.

ctx->lock was designed to prevent concurrent "amdgpu_ctx_wait_prev_fence"
calls and avoid dead reservation lock from GPU reset. since no reservation
lock is held in latest GPU reset any more, ctx->lock can be simply removed
and concurrent "amdgpu_ctx_wait_prev_fence" call also can be prevented by
PD root bo reservation lock.

call stacks:
=================
//hold lock
amdgpu_cs_ioctl->amdgpu_cs_parser_init->mutex_lock(&parser->ctx->lock);
…
//report warning
amdgpu_cs_dependencies->amdgpu_cs_process_syncobj_timeline_in_dep \
->amdgpu_syncobj_lookup_and_add_to_sync -> drm_syncobj_find_fence \
-> lockdep_assert_none_held_once
…
amdgpu_cs_ioctl->amdgpu_cs_parser_fini->mutex_unlock(&parser->ctx->lock);

Signed-off-by: Ken Xue <Ken.Xue@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index a34be65..af12256 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -127,8 +127,6 @@ 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;
@@ -585,6 +583,16 @@ static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,
                }
        }
 
+       /* Move fence waiting after getting reservation lock of
+        * PD root. Then there is no need on a ctx mutex lock.
+        */
+       r = amdgpu_ctx_wait_prev_fence(p->ctx, p->entity);
+       if (unlikely(r != 0)) {
+               if (r != -ERESTARTSYS)
+                       DRM_ERROR("amdgpu_ctx_wait_prev_fence failed.\n");
+               goto error_validate;
+       }
+
        amdgpu_cs_get_threshold_for_moves(p->adev, &p->bytes_moved_threshold,
                                          &p->bytes_moved_vis_threshold);
        p->bytes_moved = 0;
@@ -700,7 +708,6 @@ 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)
@@ -944,7 +951,7 @@ static int amdgpu_cs_ib_fill(struct amdgpu_device *adev,
        if (parser->job->uf_addr && ring->funcs->no_user_fence)
                return -EINVAL;
 
-       return amdgpu_ctx_wait_prev_fence(parser->ctx, parser->entity);
+       return 0;
 }
 
 static int amdgpu_cs_process_fence_dep(struct amdgpu_cs_parser *p,
@@ -1363,7 +1370,6 @@ 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);
 

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
index 2c929fa..1c72f60 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
@@ -230,7 +230,6 @@ 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;
@@ -352,7 +351,6 @@ static void amdgpu_ctx_fini(struct kref *ref)
                }
        }
        amdgpu_ctx_set_stable_pstate(ctx, AMDGPU_CTX_STABLE_PSTATE_NONE);
-       mutex_destroy(&ctx->lock);
        kfree(ctx);
 }
 

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h
index 142f2f8..d0cbfce 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h
@@ -49,7 +49,6 @@ 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;