drm/msm/gem: Convert to drm_exec

Replace the ww_mutex locking dance with the drm_exec helper.

v2: Error path fixes, move drm_exec_fini so we only call it once (and
    only if we have drm_exec_init()
Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/568342/

drivers/gpu/drm/msm/Kconfig

@@ -17,6 +17,7 @@ config DRM_MSM
 	select DRM_DP_AUX_BUS
 	select DRM_DISPLAY_DP_HELPER
 	select DRM_DISPLAY_HELPER
+	select DRM_EXEC
 	select DRM_KMS_HELPER
 	select DRM_PANEL
 	select DRM_BRIDGE

drivers/gpu/drm/msm/msm_gem.h

@@ -9,6 +9,7 @@
 
 #include <linux/kref.h>
 #include <linux/dma-resv.h>
+#include "drm/drm_exec.h"
 #include "drm/gpu_scheduler.h"
 #include "msm_drv.h"
 
@@ -258,7 +259,7 @@ struct msm_gem_submit {
 	struct msm_gpu *gpu;
 	struct msm_gem_address_space *aspace;
 	struct list_head node;   /* node in ring submit list */
-	struct ww_acquire_ctx ticket;
+	struct drm_exec exec;
 	uint32_t seqno;		/* Sequence number of the submit on the ring */
 
 	/* Hw fence, which is created when the scheduler executes the job, and
@@ -291,8 +292,6 @@ struct msm_gem_submit {
 		struct drm_msm_gem_submit_reloc *relocs;
 	} *cmd;  /* array of size nr_cmds */
 	struct {
-/* make sure these don't conflict w/ MSM_SUBMIT_BO_x */
-#define BO_LOCKED	0x4000	/* obj lock is held */
 		uint32_t flags;
 		union {
 			struct drm_gem_object *obj;

drivers/gpu/drm/msm/msm_gem_submit.c

@@ -248,85 +248,30 @@ static int submit_lookup_cmds(struct msm_gem_submit *submit,
 	return ret;
 }
 
-static void submit_unlock_bo(struct msm_gem_submit *submit, int i)
-{
-	struct drm_gem_object *obj = submit->bos[i].obj;
-	unsigned cleanup_flags = BO_LOCKED;
-	unsigned flags = submit->bos[i].flags & cleanup_flags;
-
-	/*
-	 * Clear flags bit before dropping lock, so that the msm_job_run()
-	 * path isn't racing with submit_cleanup() (ie. the read/modify/
-	 * write is protected by the obj lock in all paths)
-	 */
-	submit->bos[i].flags &= ~cleanup_flags;
-
-	if (flags & BO_LOCKED)
-		dma_resv_unlock(obj->resv);
-}
-
 /* This is where we make sure all the bo's are reserved and pin'd: */
 static int submit_lock_objects(struct msm_gem_submit *submit)
 {
-	int contended, slow_locked = -1, i, ret = 0;
-
-retry:
-	for (i = 0; i < submit->nr_bos; i++) {
-		struct drm_gem_object *obj = submit->bos[i].obj;
-
-		if (slow_locked == i)
-			slow_locked = -1;
+	int ret;
 
-		contended = i;
+	drm_exec_init(&submit->exec, DRM_EXEC_INTERRUPTIBLE_WAIT, submit->nr_bos);
 
-		if (!(submit->bos[i].flags & BO_LOCKED)) {
-			ret = dma_resv_lock_interruptible(obj->resv,
-							  &submit->ticket);
+	drm_exec_until_all_locked (&submit->exec) {
+		for (unsigned i = 0; i < submit->nr_bos; i++) {
+			struct drm_gem_object *obj = submit->bos[i].obj;
+			ret = drm_exec_prepare_obj(&submit->exec, obj, 1);
+			drm_exec_retry_on_contention(&submit->exec);
 			if (ret)
-				goto fail;
-			submit->bos[i].flags |= BO_LOCKED;
+				goto error;
 		}
 	}
 
-	ww_acquire_done(&submit->ticket);
-
 	return 0;
 
-fail:
-	if (ret == -EALREADY) {
-		SUBMIT_ERROR(submit, "handle %u at index %u already on submit list\n",
-			     submit->bos[i].handle, i);
-		ret = -EINVAL;
-	}
-
-	for (; i >= 0; i--)
-		submit_unlock_bo(submit, i);
-
-	if (slow_locked > 0)
-		submit_unlock_bo(submit, slow_locked);
-
-	if (ret == -EDEADLK) {
-		struct drm_gem_object *obj = submit->bos[contended].obj;
-		/* we lost out in a seqno race, lock and retry.. */
-		ret = dma_resv_lock_slow_interruptible(obj->resv,
-						       &submit->ticket);
-		if (!ret) {
-			submit->bos[contended].flags |= BO_LOCKED;
-			slow_locked = contended;
-			goto retry;
-		}
-
-		/* Not expecting -EALREADY here, if the bo was already
-		 * locked, we should have gotten -EALREADY already from
-		 * the dma_resv_lock_interruptable() call.
-		 */
-		WARN_ON_ONCE(ret == -EALREADY);
-	}
-
+error:
 	return ret;
 }
 
-static int submit_fence_sync(struct msm_gem_submit *submit, bool no_implicit)
+static int submit_fence_sync(struct msm_gem_submit *submit)
 {
 	int i, ret = 0;
 
@@ -334,22 +279,6 @@ static int submit_fence_sync(struct msm_gem_submit *submit, bool no_implicit)
 		struct drm_gem_object *obj = submit->bos[i].obj;
 		bool write = submit->bos[i].flags & MSM_SUBMIT_BO_WRITE;
 
-		/* NOTE: _reserve_shared() must happen before
-		 * _add_shared_fence(), which makes this a slightly
-		 * strange place to call it.  OTOH this is a
-		 * convenient can-fail point to hook it in.
-		 */
-		ret = dma_resv_reserve_fences(obj->resv, 1);
-		if (ret)
-			return ret;
-
-		/* If userspace has determined that explicit fencing is
-		 * used, it can disable implicit sync on the entire
-		 * submit:
-		 */
-		if (no_implicit)
-			continue;
-
 		/* Otherwise userspace can ask for implicit sync to be
 		 * disabled on specific buffers.  This is useful for internal
 		 * usermode driver managed buffers, suballocation, etc.
@@ -529,17 +458,14 @@ static int submit_reloc(struct msm_gem_submit *submit, struct drm_gem_object *ob
  */
 static void submit_cleanup(struct msm_gem_submit *submit, bool error)
 {
-	unsigned i;
-
-	if (error)
+	if (error) {
 		submit_unpin_objects(submit);
-
-	for (i = 0; i < submit->nr_bos; i++) {
-		struct drm_gem_object *obj = submit->bos[i].obj;
-		submit_unlock_bo(submit, i);
-		if (error)
-			drm_gem_object_put(obj);
+		/* job wasn't enqueued to scheduler, so early retirement: */
+		msm_submit_retire(submit);
 	}
+
+	if (submit->exec.objects)
+		drm_exec_fini(&submit->exec);
 }
 
 void msm_submit_retire(struct msm_gem_submit *submit)
@@ -733,7 +659,6 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 	struct msm_submit_post_dep *post_deps = NULL;
 	struct drm_syncobj **syncobjs_to_reset = NULL;
 	int out_fence_fd = -1;
-	bool has_ww_ticket = false;
 	unsigned i;
 	int ret;
 
@@ -839,15 +764,15 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 		goto out;
 
 	/* copy_*_user while holding a ww ticket upsets lockdep */
-	ww_acquire_init(&submit->ticket, &reservation_ww_class);
-	has_ww_ticket = true;
 	ret = submit_lock_objects(submit);
 	if (ret)
 		goto out;
 
-	ret = submit_fence_sync(submit, !!(args->flags & MSM_SUBMIT_NO_IMPLICIT));
-	if (ret)
-		goto out;
+	if (!(args->flags & MSM_SUBMIT_NO_IMPLICIT)) {
+		ret = submit_fence_sync(submit);
+		if (ret)
+			goto out;
+	}
 
 	ret = submit_pin_objects(submit);
 	if (ret)
@@ -975,8 +900,6 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 
 out:
 	submit_cleanup(submit, !!ret);
-	if (has_ww_ticket)
-		ww_acquire_fini(&submit->ticket);
 out_unlock:
 	mutex_unlock(&queue->lock);
 out_post_unlock: