Re: [PATCH v3 4/4] drm/v3d: add multiple syncobjs support

On 10/01, Iago Toral wrote:

On Thu, 2021-09-30 at 17:19 +0100, Melissa Wen wrote:

...

Using the generic extension from the previous patch, a specific multisync extension enables more than one in/out binary syncobj per job submission. Arrays of syncobjs are set in struct drm_v3d_multisync, that also cares of determining the stage for sync (wait deps) according to the job queue.

v2:

• subclass the generic extension struct (Daniel)
• simplify adding dependency conditions to make understandable (Iago)

v3:

• fix conditions to consider single or multiples in/out_syncs (Iago)
• remove irrelevant comment (Iago)

Signed-off-by: Melissa Wen mwen@igalia.com

drivers/gpu/drm/v3d/v3d_drv.c | 6 +- drivers/gpu/drm/v3d/v3d_drv.h | 24 +++-- drivers/gpu/drm/v3d/v3d_gem.c | 185 ++++++++++++++++++++++++++++++

---

include/uapi/drm/v3d_drm.h | 49 ++++++++- 4 files changed, 232 insertions(+), 32 deletions(-)

diff --git a/drivers/gpu/drm/v3d/v3d_drv.c b/drivers/gpu/drm/v3d/v3d_drv.c index 3d6b9bcce2f7..bd46396a1ae0 100644 --- a/drivers/gpu/drm/v3d/v3d_drv.c +++ b/drivers/gpu/drm/v3d/v3d_drv.c @@ -96,6 +96,9 @@ static int v3d_get_param_ioctl(struct drm_device

(...)

...

@@ -516,9 +536,11 @@ v3d_attach_fences_and_unlock_reservation(struct drm_file *file_priv, struct v3d_job *job, struct ww_acquire_ctx *acquire_ctx, u32 out_sync,

• 			 struct v3d_submit_ext *se,
  		 struct dma_fence *done_fence)
  

{ struct drm_syncobj *sync_out;

• bool has_multisync = se && (se->flags &

We always pass the 'se' pointer from a local variable allocated in the stack of the caller so it is never going to be NULL.

I am happy to keep the NULL check if you want to protect against future changes just in case, but if we do that then...

...

DRM_V3D_EXT_ID_MULTI_SYNC); int i;

for (i = 0; i < job->bo_count; i++) {

(...)

...

+static void +v3d_put_multisync_post_deps(struct v3d_submit_ext *se) +{

• unsigned int i;
• if (!se->out_sync_count)

...we should also check for NULL here for consistency.

yes, consistency makes sense here.

Also, I think there is another problem in the code: we always call v3d_job_cleanup for failed jobs, but only call v3d_job_put for successful jobs. However, reading the docs for drm_sched_job_init:

"Drivers must make sure drm_sched_job_cleanup() if this function returns successfully, even when @job is aborted before drm_sched_job_arm() is called."

So my understanding is that we should call v3d_job_cleanup instead of v3d_job_put for successful jobs or we would be leaking sched resources on every successful job, no?

When job_init is successful, v3d_job_cleanup is called by scheduler when job is completed. drm_sched_job_cleanup describes how it works after drm_sched_job_arm:

" After that point of no return @job is committed to be executed by the scheduler, and this function should be called from the &drm_sched_backend_ops.free_job callback."

On v3d_sched.c, .free_job points to v3d_sched_job_free(), which in turn calls v3d_job_cleanup() (and then drm_sched_job_cleanup). So, it looks ok.

Also, we can say that the very last v3d_job_put() is in charge to decrement refcount initialized (set 1) in v3d_job_init(); while the v3d_job_cleanup() from v3d_sched_job_free() callback decrements refcount that was incremented when v3d_job_push() pushed the job to the scheduler.

So, refcount pairs seem consistent, I mean, get and put. And about drm_sched_job_cleanup, it is explicitly called when job_init fails or after that by the scheduler.

Thanks,

Melissa

Iago

...

• return;
  

• for (i = 0; i < se->out_sync_count; i++)

• drm_syncobj_put(se->out_syncs[i].syncobj);
  

• kvfree(se->out_syncs);

+}

+static int +v3d_get_multisync_post_deps(struct drm_file *file_priv,

• 	    struct v3d_submit_ext *se,
  

• 	    u32 count, u64 handles)
  

+{

• struct drm_v3d_sem __user *post_deps;
• int i, ret;
• if (!count)

• return 0;
  

• se->out_syncs = (struct v3d_submit_outsync *)

• 	kvmalloc_array(count,
  

• 		       sizeof(struct
  

v3d_submit_outsync),

• 		       GFP_KERNEL);
  

• if (!se->out_syncs)

• return -ENOMEM;
  

• post_deps = u64_to_user_ptr(handles);
• for (i = 0; i < count; i++) {

• struct drm_v3d_sem out;
  

• ret = copy_from_user(&out, post_deps++, sizeof(out));
  

• if (ret) {
  

• 	DRM_DEBUG("Failed to copy post dep handles\n");
  

• 	goto fail;
  

• }
  

• se->out_syncs[i].syncobj = drm_syncobj_find(file_priv,
  

• 					    out.handle)
  

;

• if (!se->out_syncs[i].syncobj) {
  

• 	ret = -EINVAL;
  

• 	goto fail;
  

• }
  

  }
• se->out_sync_count = count;
• return 0;

+fail:

• for (i--; i >= 0; i--)

• drm_syncobj_put(se->out_syncs[i].syncobj);
  

• kvfree(se->out_syncs);
• return ret;

+}

+/* Get data for multiple binary semaphores synchronization. Parse syncobj

• • to be signaled when job completes (out_sync).
• */

+static int +v3d_get_multisync_submit_deps(struct drm_file *file_priv,

• 	      struct drm_v3d_extension __user *ext,
  

• 	      void *data)
  

+{

• struct drm_v3d_multi_sync multisync;
• struct v3d_submit_ext *se = data;
• int ret;
• ret = copy_from_user(&multisync, ext, sizeof(multisync));
• if (ret)

• return ret;
  

• if (multisync.pad)

• return -EINVAL;
  

• ret = v3d_get_multisync_post_deps(file_priv, data,

multisync.out_sync_count,

• 			  multisync.out_syncs);
  

• if (ret)

• return ret;
  

• se->in_sync_count = multisync.in_sync_count;
• se->in_syncs = multisync.in_syncs;
• se->flags |= DRM_V3D_EXT_ID_MULTI_SYNC;
• se->wait_stage = multisync.wait_stage;
• return 0;

}

/* Whenever userspace sets ioctl extensions, v3d_get_extensions parses data

• according to the extension id (name).

*/ static int -v3d_get_extensions(struct drm_file *file_priv, u64 ext_handles) +v3d_get_extensions(struct drm_file *file_priv,

•    u64 ext_handles,
  

•    void *data)
  

{ struct drm_v3d_extension __user *user_ext;

• int ret;

  user_ext = u64_to_user_ptr(ext_handles); while (user_ext) {

@@ -555,7 +687,11 @@ v3d_get_extensions(struct drm_file *file_priv, u64 ext_handles) }

switch (ext.id) {

• case 0:
  

• case DRM_V3D_EXT_ID_MULTI_SYNC:
  

• 	ret = v3d_get_multisync_submit_deps(file_priv,
  

user_ext, data);

• 	if (ret)
  

• 		return ret;
  

• 	break;
  

  default: DRM_DEBUG_DRIVER("Unknown extension id: %d\n",

ext.id); return -EINVAL; @@ -586,6 +722,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data, struct v3d_dev *v3d = to_v3d_dev(dev); struct v3d_file_priv *v3d_priv = file_priv->driver_priv; struct drm_v3d_submit_cl *args = data;

• struct v3d_submit_ext se = {0}; struct v3d_bin_job *bin = NULL; struct v3d_render_job *render = NULL; struct v3d_job *clean_job = NULL;

@@ -606,7 +743,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data, }

if (args->flags & DRM_V3D_SUBMIT_EXTENSION) {

• ret = v3d_get_extensions(file_priv, args->extensions);
  

• ret = v3d_get_extensions(file_priv, args->extensions,
  

&se); if (ret) { DRM_DEBUG("Failed to get extensions.\n"); return ret; @@ -614,7 +751,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data, }

ret = v3d_job_init(v3d, file_priv, (void *)&render, sizeof(*render),

• 	   v3d_render_job_free, args->in_sync_rcl,
  

V3D_RENDER);

• 	   v3d_render_job_free, args->in_sync_rcl, &se,
  

V3D_RENDER); if (ret) goto fail;

@@ -624,7 +761,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,

if (args->bcl_start != args->bcl_end) { ret = v3d_job_init(v3d, file_priv, (void *)&bin, sizeof(*bin),

• 		   v3d_job_free, args->in_sync_bcl,
  

V3D_BIN);

• 		   v3d_job_free, args->in_sync_bcl,
  

&se, V3D_BIN); if (ret) goto fail;

@@ -638,7 +775,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,

if (args->flags & DRM_V3D_SUBMIT_CL_FLUSH_CACHE) { ret = v3d_job_init(v3d, file_priv, (void *)&clean_job, sizeof(*clean_job),

• 		   v3d_job_free, 0, V3D_CACHE_CLEAN);
  

• 		   v3d_job_free, 0, 0,
  

V3D_CACHE_CLEAN); if (ret) goto fail;

@@ -698,6 +835,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data, last_job, &acquire_ctx, args->out_sync,

• 				 &se,
  			 last_job->done_fence);
  
  

  if (bin)

@@ -716,6 +854,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data, v3d_job_cleanup((void *)bin); v3d_job_cleanup((void *)render); v3d_job_cleanup(clean_job);

• v3d_put_multisync_post_deps(&se);

  return ret;

} @@ -735,6 +874,7 @@ v3d_submit_tfu_ioctl(struct drm_device *dev, void *data, { struct v3d_dev *v3d = to_v3d_dev(dev); struct drm_v3d_submit_tfu *args = data;

• struct v3d_submit_ext se = {0}; struct v3d_tfu_job *job = NULL; struct ww_acquire_ctx acquire_ctx; int ret = 0;

@@ -747,7 +887,7 @@ v3d_submit_tfu_ioctl(struct drm_device *dev, void *data, }

if (args->flags & DRM_V3D_SUBMIT_EXTENSION) {

• ret = v3d_get_extensions(file_priv, args->extensions);
  

• ret = v3d_get_extensions(file_priv, args->extensions,
  

&se); if (ret) { DRM_DEBUG("Failed to get extensions.\n"); return ret; @@ -755,7 +895,7 @@ v3d_submit_tfu_ioctl(struct drm_device *dev, void *data, }

ret = v3d_job_init(v3d, file_priv, (void *)&job, sizeof(*job),

• 	   v3d_job_free, args->in_sync, V3D_TFU);
  

• 	   v3d_job_free, args->in_sync, &se, V3D_TFU);
  

  if (ret) goto fail;

@@ -803,6 +943,7 @@ v3d_submit_tfu_ioctl(struct drm_device *dev, void *data, v3d_attach_fences_and_unlock_reservation(file_priv, &job->base, &acquire_ctx, args->out_sync,

• 				 &se,
  			 job->base.done_fence);
  
  

  v3d_job_put(&job->base);

@@ -811,6 +952,7 @@ v3d_submit_tfu_ioctl(struct drm_device *dev, void *data,

fail: v3d_job_cleanup((void *)job);

• v3d_put_multisync_post_deps(&se);

  return ret;

} @@ -831,6 +973,7 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data, struct v3d_dev *v3d = to_v3d_dev(dev); struct v3d_file_priv *v3d_priv = file_priv->driver_priv; struct drm_v3d_submit_csd *args = data;

• struct v3d_submit_ext se = {0}; struct v3d_csd_job *job = NULL; struct v3d_job *clean_job = NULL; struct ww_acquire_ctx acquire_ctx;

@@ -852,7 +995,7 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data, }

if (args->flags & DRM_V3D_SUBMIT_EXTENSION) {

• ret = v3d_get_extensions(file_priv, args->extensions);
  

• ret = v3d_get_extensions(file_priv, args->extensions,
  

&se); if (ret) { DRM_DEBUG("Failed to get extensions.\n"); return ret; @@ -860,12 +1003,12 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data, }

ret = v3d_job_init(v3d, file_priv, (void *)&job, sizeof(*job),

• 	   v3d_job_free, args->in_sync, V3D_CSD);
  

• 	   v3d_job_free, args->in_sync, &se, V3D_CSD);
  

  if (ret) goto fail;

  ret = v3d_job_init(v3d, file_priv, (void *)&clean_job,

sizeof(*clean_job),

• 	   v3d_job_free, 0, V3D_CACHE_CLEAN);
  

• 	   v3d_job_free, 0, 0, V3D_CACHE_CLEAN);
  

  if (ret) goto fail;

@@ -904,6 +1047,7 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data, clean_job, &acquire_ctx, args->out_sync,

• 				 &se,
  			 clean_job-
  

...

done_fence);

v3d_job_put(&job->base); @@ -918,6 +1062,7 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data, fail: v3d_job_cleanup((void *)job); v3d_job_cleanup(clean_job);

• v3d_put_multisync_post_deps(&se);

  return ret;

} diff --git a/include/uapi/drm/v3d_drm.h b/include/uapi/drm/v3d_drm.h index 55b443ca6c0b..3dfc0af8756a 100644 --- a/include/uapi/drm/v3d_drm.h +++ b/include/uapi/drm/v3d_drm.h @@ -73,6 +73,53 @@ struct drm_v3d_extension { __u32 flags; /* mbz */ };

+/* struct drm_v3d_sem - wait/signal semaphore

• • If binary semaphore, it only takes syncobj handle and ignores

flags and

• • point fields. Point is defined for timeline syncobj feature.
• */

+struct drm_v3d_sem {

• __u32 handle; /* syncobj */
• /* rsv below, for future uses */
• __u32 flags;
• __u64 point; /* for timeline sem support */
• __u64 mbz[2]; /* must be zero, rsv */

+};

+/* Enum for each of the V3D queues. */ +enum v3d_queue {

• V3D_BIN,
• V3D_RENDER,
• V3D_TFU,
• V3D_CSD,
• V3D_CACHE_CLEAN,

+};

+/**

• • struct drm_v3d_multi_sync - ioctl extension to add support

multiples

• • syncobjs for commands submission.
• • When an extension of DRM_V3D_EXT_ID_MULTI_SYNC id is defined, it

points to

• • this extension to define wait and signal dependencies, instead of

single

• • in/out sync entries on submitting commands. The field flags is

used to

• • determine the stage to set wait dependencies.
• */

+struct drm_v3d_multi_sync {

• struct drm_v3d_extension base;
• /* Array of wait and signal semaphores */
• __u64 in_syncs;
• __u64 out_syncs;
• /* Number of entries */
• __u32 in_sync_count;
• __u32 out_sync_count;
• /* set the stage (v3d_queue) to sync */
• __u32 wait_stage;
• __u32 pad; /* mbz */

+};

/**

• struct drm_v3d_submit_cl - ioctl argument for submitting commands

to the 3D

• engine.

@@ -228,6 +275,7 @@ enum drm_v3d_param { DRM_V3D_PARAM_SUPPORTS_CSD, DRM_V3D_PARAM_SUPPORTS_CACHE_FLUSH, DRM_V3D_PARAM_SUPPORTS_PERFMON,

• DRM_V3D_PARAM_SUPPORTS_MULTISYNC_EXT,

};

struct drm_v3d_get_param { @@ -271,7 +319,6 @@ struct drm_v3d_submit_tfu {

/* Pointer to an array of ioctl extensions*/ __u64 extensions;

};

/* Submits a compute shader for dispatch. This job will block on any