[PATCH 07/11] drm/msm: Track "seqno" fences by idr

Rob Clark
2021-07-17T20:25:51Z

Previously the (non-fd) fence returned from submit ioctl was a raw
seqno, which is scoped to the ring. But from UABI standpoint, the
ioctls related to seqno fences all specify a submitqueue. We can
take advantage of that to replace the seqno fences with a cyclic idr
handle.

This is in preperation for moving to drm scheduler, at which point
the submit ioctl will return after queuing the submit job to the
scheduler, but before the submit is written into the ring (and
therefore before a ring seqno has been assigned). Which means we
need to replace the dma_fence that userspace may need to wait on
with a scheduler fence.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
drivers/gpu/drm/msm/msm_drv.c | 30 +++++++++++++++++++--
drivers/gpu/drm/msm/msm_fence.c | 39 ---------------------------
drivers/gpu/drm/msm/msm_fence.h | 2 --
drivers/gpu/drm/msm/msm_gem.h | 1 +
drivers/gpu/drm/msm/msm_gem_submit.c | 23 +++++++++++++++-
drivers/gpu/drm/msm/msm_gpu.h | 5 ++++
drivers/gpu/drm/msm/msm_submitqueue.c | 5 ++++
7 files changed, 61 insertions(+), 44 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 9b8fa2ad0d84..1594ae39d54f 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -911,6 +911,7 @@ static int msm_ioctl_wait_fence(struct drm_device *dev, void *data,
ktime_t timeout = to_ktime(args->timeout);
struct msm_gpu_submitqueue *queue;
struct msm_gpu *gpu = priv->gpu;
+ struct dma_fence *fence;
int ret;

if (args->pad) {
@@ -925,10 +926,35 @@ static int msm_ioctl_wait_fence(struct drm_device *dev, void *data,
if (!queue)
return -ENOENT;

- ret = msm_wait_fence(gpu->rb[queue->prio]->fctx, args->fence, &timeout,
- true);
+ /*
+ * Map submitqueue scoped "seqno" (which is actually an idr key)
+ * back to underlying dma-fence
+ *
+ * The fence is removed from the fence_idr when the submit is
+ * retired, so if the fence is not found it means there is nothing
+ * to wait for
+ */
+ ret = mutex_lock_interruptible(&queue->lock);
+ if (ret)
+ return ret;
+ fence = idr_find(&queue->fence_idr, args->fence);
+ if (fence)
+ fence = dma_fence_get_rcu(fence);
+ mutex_unlock(&queue->lock);
+
+ if (!fence)
+ return 0;

+ ret = dma_fence_wait_timeout(fence, true, timeout_to_jiffies(&timeout));
+ if (ret == 0) {
+ ret = -ETIMEDOUT;
+ } else if (ret != -ERESTARTSYS) {
+ ret = 0;
+ }
+
+ dma_fence_put(fence);
msm_submitqueue_put(queue);
+
return ret;
}

diff --git a/drivers/gpu/drm/msm/msm_fence.c b/drivers/gpu/drm/msm/msm_fence.c
index e58895603726..efa86807e622 100644
--- a/drivers/gpu/drm/msm/msm_fence.c
+++ b/drivers/gpu/drm/msm/msm_fence.c
@@ -39,45 +39,6 @@ static inline bool fence_completed(struct msm_fence_context *fctx, uint32_t fenc
return (int32_t)(fctx->completed_fence - fence) >= 0;
}

-/* legacy path for WAIT_FENCE ioctl: */
-int msm_wait_fence(struct msm_fence_context *fctx, uint32_t fence,
- ktime_t *timeout, bool interruptible)
-{
- int ret;
-
- if (fence > fctx->last_fence) {
- DRM_ERROR_RATELIMITED("%s: waiting on invalid fence: %u (of %u)\n",
- fctx->name, fence, fctx->last_fence);
- return -EINVAL;
- }
-
- if (!timeout) {
- /* no-wait: */
- ret = fence_completed(fctx, fence) ? 0 : -EBUSY;
- } else {
- unsigned long remaining_jiffies = timeout_to_jiffies(timeout);
-
- if (interruptible)
- ret = wait_event_interruptible_timeout(fctx->event,
- fence_completed(fctx, fence),
- remaining_jiffies);
- else
- ret = wait_event_timeout(fctx->event,
- fence_completed(fctx, fence),
- remaining_jiffies);
-
- if (ret == 0) {
- DBG("timeout waiting for fence: %u (completed: %u)",
- fence, fctx->completed_fence);
- ret = -ETIMEDOUT;
- } else if (ret != -ERESTARTSYS) {
- ret = 0;
- }
- }
-
- return ret;
-}
-
/* called from workqueue */
void msm_update_fence(struct msm_fence_context *fctx, uint32_t fence)
{
diff --git a/drivers/gpu/drm/msm/msm_fence.h b/drivers/gpu/drm/msm/msm_fence.h
index 2d9af66dcca5..98d495ce2dee 100644
--- a/drivers/gpu/drm/msm/msm_fence.h
+++ b/drivers/gpu/drm/msm/msm_fence.h
@@ -24,8 +24,6 @@ struct msm_fence_context * msm_fence_context_alloc(struct drm_device *dev,
const char *name);
void msm_fence_context_free(struct msm_fence_context *fctx);

-int msm_wait_fence(struct msm_fence_context *fctx, uint32_t fence,
- ktime_t *timeout, bool interruptible);
void msm_update_fence(struct msm_fence_context *fctx, uint32_t fence);

struct dma_fence * msm_fence_alloc(struct msm_fence_context *fctx);
diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h
index da3af702a6c8..e0579abda5b9 100644
--- a/drivers/gpu/drm/msm/msm_gem.h
+++ b/drivers/gpu/drm/msm/msm_gem.h
@@ -320,6 +320,7 @@ struct msm_gem_submit {
struct ww_acquire_ctx ticket;
uint32_t seqno; /* Sequence number of the submit on the ring */
struct dma_fence *fence;
+ int fence_id; /* key into queue->fence_idr */
struct msm_gpu_submitqueue *queue;
struct pid *pid; /* submitting process */
bool fault_dumped; /* Limit devcoredump dumping to one per submit */
diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
index 4f02fa3c78f9..f6f595aae2c5 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -68,7 +68,14 @@ void __msm_gem_submit_destroy(struct kref *kref)
container_of(kref, struct msm_gem_submit, ref);
unsigned i;

+ if (submit->fence_id) {
+ mutex_lock(&submit->queue->lock);
+ idr_remove(&submit->queue->fence_idr, submit->fence_id);
+ mutex_unlock(&submit->queue->lock);
+ }
+
dma_fence_put(submit->fence);
+
put_pid(submit->pid);
msm_submitqueue_put(submit->queue);

@@ -872,6 +879,20 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
goto out;
}

+ /*
+ * Allocate an id which can be used by WAIT_FENCE ioctl to map back
+ * to the underlying fence.
+ */
+ mutex_lock(&queue->lock);
+ submit->fence_id = idr_alloc_cyclic(&queue->fence_idr,
+ submit->fence, 0, INT_MAX, GFP_KERNEL);
+ mutex_unlock(&queue->lock);
+ if (submit->fence_id < 0) {
+ ret = submit->fence_id = 0;
+ submit->fence_id = 0;
+ goto out;
+ }
+
if (args->flags & MSM_SUBMIT_FENCE_FD_OUT) {
struct sync_file *sync_file = sync_file_create(submit->fence);
if (!sync_file) {
@@ -886,7 +907,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,

msm_gpu_submit(gpu, submit);

- args->fence = submit->fence->seqno;
+ args->fence = submit->fence_id;

msm_reset_syncobjs(syncobjs_to_reset, args->nr_in_syncobjs);
msm_process_post_deps(post_deps, args->nr_out_syncobjs,
diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index f3609eca5c8f..cc4e4a9ac1c2 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -221,6 +221,9 @@ struct msm_gpu_perfcntr {
* which set of pgtables do submits jobs associated with the
* submitqueue use)
* @node: node in the context's list of submitqueues
+ * @fence_idr: maps fence-id to dma_fence for userspace visible fence
+ * seqno, protected by submitqueue lock
+ * @lock: submitqueue lock
* @ref: reference count
*/
struct msm_gpu_submitqueue {
@@ -230,6 +233,8 @@ struct msm_gpu_submitqueue {
int faults;
struct msm_file_private *ctx;
struct list_head node;
+ struct idr fence_idr;
+ struct mutex lock;
struct kref ref;
};

diff --git a/drivers/gpu/drm/msm/msm_submitqueue.c b/drivers/gpu/drm/msm/msm_submitqueue.c
index fbea6e7adf40..75cded54d571 100644
--- a/drivers/gpu/drm/msm/msm_submitqueue.c
+++ b/drivers/gpu/drm/msm/msm_submitqueue.c
@@ -12,6 +12,8 @@ void msm_submitqueue_destroy(struct kref *kref)
struct msm_gpu_submitqueue *queue = container_of(kref,
struct msm_gpu_submitqueue, ref);

+ idr_destroy(&queue->fence_idr);
+
msm_file_private_put(queue->ctx);

kfree(queue);
@@ -89,6 +91,9 @@ int msm_submitqueue_create(struct drm_device *drm, struct msm_file_private *ctx,
if (id)
*id = queue->id;

+ idr_init(&queue->fence_idr);
+ mutex_init(&queue->lock);
+
list_add_tail(&queue->node, &ctx->submitqueues);

write_unlock(&ctx->queuelock);
--
2.31.1