If a syncobj has not yet been assigned, treat it as a future fence and install and wait upon a dma-fence-proxy. The proxy will be replace by the real fence later, and that fence will be responsible for signaling our waiter. Link: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4854 Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> --- .../gpu/drm/i915/gem/i915_gem_execbuffer.c | 21 ++- drivers/gpu/drm/i915/i915_request.c | 133 ++++++++++++++++++ drivers/gpu/drm/i915/i915_scheduler.c | 41 ++++++ drivers/gpu/drm/i915/i915_scheduler.h | 3 + 4 files changed, 196 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c index 966523a8503f..7abb96505a31 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c @@ -5,6 +5,7 @@ */ #include <linux/intel-iommu.h> +#include <linux/dma-fence-proxy.h> #include <linux/dma-resv.h> #include <linux/sync_file.h> #include <linux/uaccess.h> @@ -2524,8 +2525,24 @@ await_fence_array(struct i915_execbuffer *eb, continue; fence = drm_syncobj_fence_get(syncobj); - if (!fence) - return -EINVAL; + if (!fence) { + struct dma_fence *old; + + fence = dma_fence_create_proxy(); + if (!fence) + return -ENOMEM; + + spin_lock(&syncobj->lock); + old = rcu_dereference_protected(syncobj->fence, true); + if (unlikely(old)) { + dma_fence_put(fence); + fence = dma_fence_get(old); + } else { + rcu_assign_pointer(syncobj->fence, + dma_fence_get(fence)); + } + spin_unlock(&syncobj->lock); + } err = i915_request_await_dma_fence(eb->request, fence); dma_fence_put(fence); diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index d369b25e46bb..9c5de07db47d 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -23,6 +23,7 @@ */ #include <linux/dma-fence-array.h> +#include <linux/dma-fence-proxy.h> #include <linux/irq_work.h> #include <linux/prefetch.h> #include <linux/sched.h> @@ -1065,6 +1066,136 @@ i915_request_await_request(struct i915_request *to, struct i915_request *from) return 0; } +struct await_proxy { + struct wait_queue_entry base; + struct i915_request *request; + struct dma_fence *fence; + struct timer_list timer; + struct work_struct work; + int (*attach)(struct await_proxy *ap); + void *data; +}; + +static void await_proxy_work(struct work_struct *work) +{ + struct await_proxy *ap = container_of(work, typeof(*ap), work); + struct i915_request *rq = ap->request; + + del_timer_sync(&ap->timer); + + if (ap->fence) { + int err = 0; + + /* + * If the fence is external, we impose a 10s timeout. + * However, if the fence is internal, we skip a timeout in + * the belief that all fences are in-order (DAG, no cycles) + * and we can enforce forward progress by reset the GPU if + * necessary. A future fence, provided userspace, can trivially + * generate a cycle in the dependency graph, and so cause + * that entire cycle to become deadlocked and for no forward + * progress to either be made, and the driver being kept + * eternally awake. + */ + if (dma_fence_is_i915(ap->fence) && + !i915_sched_node_verify_dag(&rq->sched, + &to_request(ap->fence)->sched)) + err = -EDEADLK; + + if (!err) { + mutex_lock(&rq->context->timeline->mutex); + err = ap->attach(ap); + mutex_unlock(&rq->context->timeline->mutex); + } + + if (err < 0) + i915_sw_fence_set_error_once(&rq->submit, err); + } + + i915_sw_fence_complete(&rq->submit); + + dma_fence_put(ap->fence); + kfree(ap); +} + +static int +await_proxy_wake(struct wait_queue_entry *entry, + unsigned int mode, + int flags, + void *fence) +{ + struct await_proxy *ap = container_of(entry, typeof(*ap), base); + + ap->fence = dma_fence_get(fence); + schedule_work(&ap->work); + + return 0; +} + +static void +await_proxy_timer(struct timer_list *t) +{ + struct await_proxy *ap = container_of(t, typeof(*ap), timer); + + if (dma_fence_remove_proxy_listener(ap->base.private, &ap->base)) { + struct i915_request *rq = ap->request; + + pr_notice("Asynchronous wait on unset proxy fence by %s:%s:%llx timed out\n", + rq->fence.ops->get_driver_name(&rq->fence), + rq->fence.ops->get_timeline_name(&rq->fence), + rq->fence.seqno); + i915_sw_fence_set_error_once(&rq->submit, -ETIMEDOUT); + + schedule_work(&ap->work); + } +} + +static int +__i915_request_await_proxy(struct i915_request *rq, + struct dma_fence *fence, + unsigned long timeout, + int (*attach)(struct await_proxy *ap), + void *data) +{ + struct await_proxy *ap; + + ap = kzalloc(sizeof(*ap), I915_FENCE_GFP); + if (!ap) + return -ENOMEM; + + i915_sw_fence_await(&rq->submit); + + ap->base.private = fence; + ap->base.func = await_proxy_wake; + ap->request = rq; + INIT_WORK(&ap->work, await_proxy_work); + ap->attach = attach; + ap->data = data; + + timer_setup(&ap->timer, await_proxy_timer, 0); + if (timeout) + mod_timer(&ap->timer, round_jiffies_up(jiffies + timeout)); + + dma_fence_add_proxy_listener(fence, &ap->base); + return 0; +} + +static int await_proxy(struct await_proxy *ap) +{ + return i915_request_await_dma_fence(ap->request, ap->fence); +} + +static int +i915_request_await_proxy(struct i915_request *rq, struct dma_fence *fence) +{ + /* + * Wait until we know the real fence so that can optimise the + * inter-fence synchronisation. + */ + return __i915_request_await_proxy(rq, fence, I915_FENCE_TIMEOUT, + await_proxy, NULL); +} + int i915_request_await_dma_fence(struct i915_request *rq, struct dma_fence *fence) { @@ -1111,6 +1242,8 @@ i915_request_await_dma_fence(struct i915_request *rq, struct dma_fence *fence) if (dma_fence_is_i915(fence)) ret = i915_request_await_request(rq, to_request(fence)); + else if (dma_fence_is_proxy(fence)) + ret = i915_request_await_proxy(rq, fence); else ret = i915_sw_fence_await_dma_fence(&rq->submit, fence, fence->context ? I915_FENCE_TIMEOUT : 0, diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c index 5f4c1e49e974..ad6c4363eaa6 100644 --- a/drivers/gpu/drm/i915/i915_scheduler.c +++ b/drivers/gpu/drm/i915/i915_scheduler.c @@ -484,6 +484,47 @@ int i915_sched_node_add_dependency(struct i915_sched_node *node, return 0; } +bool i915_sched_node_verify_dag(struct i915_sched_node *waiter, + struct i915_sched_node *signaler) +{ + struct i915_dependency *dep, *p; + struct i915_dependency stack; + bool result = false; + LIST_HEAD(dfs); + + if (waiter == signaler) + return true; + + spin_lock_irq(&schedule_lock); + + stack.signaler = signaler; + list_add(&stack.dfs_link, &dfs); + + list_for_each_entry(dep, &dfs, dfs_link) { + struct i915_sched_node *node = dep->signaler; + + if (node_signaled(node)) + continue; + + list_for_each_entry(p, &node->signalers_list, signal_link) { + if (p->signaler == waiter) + goto out; + + if (list_empty(&p->dfs_link)) + list_add_tail(&p->dfs_link, &dfs); + } + } + + result = true; +out: + list_for_each_entry_safe(dep, p, &dfs, dfs_link) + INIT_LIST_HEAD(&dep->dfs_link); + + spin_unlock_irq(&schedule_lock); + + return result; +} + void i915_sched_node_fini(struct i915_sched_node *node) { struct i915_dependency *dep, *tmp; diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h index 6f0bf00fc569..13432add8929 100644 --- a/drivers/gpu/drm/i915/i915_scheduler.h +++ b/drivers/gpu/drm/i915/i915_scheduler.h @@ -28,6 +28,9 @@ void i915_sched_node_init(struct i915_sched_node *node); void i915_sched_node_reinit(struct i915_sched_node *node); +bool i915_sched_node_verify_dag(struct i915_sched_node *waiter, + struct i915_sched_node *signal); + bool __i915_sched_node_add_dependency(struct i915_sched_node *node, struct i915_sched_node *signal, struct i915_dependency *dep, -- 2.20.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
