1 files changed, 278 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_wait.c b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
new file mode 100644
index 000000000000..26ec6579b7cd
--- /dev/null
+++ b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
@@ -0,0 +1,278 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2016 Intel Corporation
+ */
+
+#include <linux/dma-fence-array.h>
+#include <linux/jiffies.h>
+
+#include "gt/intel_engine.h"
+
+#include "i915_gem_ioctls.h"
+#include "i915_gem_object.h"
+
+static long
+i915_gem_object_wait_fence(struct dma_fence *fence,
+			   unsigned int flags,
+			   long timeout)
+{
+	BUILD_BUG_ON(I915_WAIT_INTERRUPTIBLE != 0x1);
+
+	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+		return timeout;
+
+	if (dma_fence_is_i915(fence))
+		return i915_request_wait(to_request(fence), flags, timeout);
+
+	return dma_fence_wait_timeout(fence,
+				      flags & I915_WAIT_INTERRUPTIBLE,
+				      timeout);
+}
+
+static long
+i915_gem_object_wait_reservation(struct reservation_object *resv,
+				 unsigned int flags,
+				 long timeout)
+{
+	unsigned int seq = __read_seqcount_begin(&resv->seq);
+	struct dma_fence *excl;
+	bool prune_fences = false;
+
+	if (flags & I915_WAIT_ALL) {
+		struct dma_fence **shared;
+		unsigned int count, i;
+		int ret;
+
+		ret = reservation_object_get_fences_rcu(resv,
+							&excl, &count, &shared);
+		if (ret)
+			return ret;
+
+		for (i = 0; i < count; i++) {
+			timeout = i915_gem_object_wait_fence(shared[i],
+							     flags, timeout);
+			if (timeout < 0)
+				break;
+
+			dma_fence_put(shared[i]);
+		}
+
+		for (; i < count; i++)
+			dma_fence_put(shared[i]);
+		kfree(shared);
+
+		/*
+		 * If both shared fences and an exclusive fence exist,
+		 * then by construction the shared fences must be later
+		 * than the exclusive fence. If we successfully wait for
+		 * all the shared fences, we know that the exclusive fence
+		 * must all be signaled. If all the shared fences are
+		 * signaled, we can prune the array and recover the
+		 * floating references on the fences/requests.
+		 */
+		prune_fences = count && timeout >= 0;
+	} else {
+		excl = reservation_object_get_excl_rcu(resv);
+	}
+
+	if (excl && timeout >= 0)
+		timeout = i915_gem_object_wait_fence(excl, flags, timeout);
+
+	dma_fence_put(excl);
+
+	/*
+	 * Opportunistically prune the fences iff we know they have *all* been
+	 * signaled and that the reservation object has not been changed (i.e.
+	 * no new fences have been added).
+	 */
+	if (prune_fences && !__read_seqcount_retry(&resv->seq, seq)) {
+		if (reservation_object_trylock(resv)) {
+			if (!__read_seqcount_retry(&resv->seq, seq))
+				reservation_object_add_excl_fence(resv, NULL);
+			reservation_object_unlock(resv);
+		}
+	}
+
+	return timeout;
+}
+
+static void __fence_set_priority(struct dma_fence *fence,
+				 const struct i915_sched_attr *attr)
+{
+	struct i915_request *rq;
+	struct intel_engine_cs *engine;
+
+	if (dma_fence_is_signaled(fence) || !dma_fence_is_i915(fence))
+		return;
+
+	rq = to_request(fence);
+	engine = rq->engine;
+
+	local_bh_disable();
+	rcu_read_lock(); /* RCU serialisation for set-wedged protection */
+	if (engine->schedule)
+		engine->schedule(rq, attr);
+	rcu_read_unlock();
+	local_bh_enable(); /* kick the tasklets if queues were reprioritised */
+}
+
+static void fence_set_priority(struct dma_fence *fence,
+			       const struct i915_sched_attr *attr)
+{
+	/* Recurse once into a fence-array */
+	if (dma_fence_is_array(fence)) {
+		struct dma_fence_array *array = to_dma_fence_array(fence);
+		int i;
+
+		for (i = 0; i < array->num_fences; i++)
+			__fence_set_priority(array->fences[i], attr);
+	} else {
+		__fence_set_priority(fence, attr);
+	}
+}
+
+int
+i915_gem_object_wait_priority(struct drm_i915_gem_object *obj,
+			      unsigned int flags,
+			      const struct i915_sched_attr *attr)
+{
+	struct dma_fence *excl;
+
+	if (flags & I915_WAIT_ALL) {
+		struct dma_fence **shared;
+		unsigned int count, i;
+		int ret;
+
+		ret = reservation_object_get_fences_rcu(obj->base.resv,
+							&excl, &count, &shared);
+		if (ret)
+			return ret;
+
+		for (i = 0; i < count; i++) {
+			fence_set_priority(shared[i], attr);
+			dma_fence_put(shared[i]);
+		}
+
+		kfree(shared);
+	} else {
+		excl = reservation_object_get_excl_rcu(obj->base.resv);
+	}
+
+	if (excl) {
+		fence_set_priority(excl, attr);
+		dma_fence_put(excl);
+	}
+	return 0;
+}
+
+/**
+ * Waits for rendering to the object to be completed
+ * @obj: i915 gem object
+ * @flags: how to wait (under a lock, for all rendering or just for writes etc)
+ * @timeout: how long to wait
+ */
+int
+i915_gem_object_wait(struct drm_i915_gem_object *obj,
+		     unsigned int flags,
+		     long timeout)
+{
+	might_sleep();
+	GEM_BUG_ON(timeout < 0);
+
+	timeout = i915_gem_object_wait_reservation(obj->base.resv,
+						   flags, timeout);
+	return timeout < 0 ? timeout : 0;
+}
+
+static inline unsigned long nsecs_to_jiffies_timeout(const u64 n)
+{
+	/* nsecs_to_jiffies64() does not guard against overflow */
+	if (NSEC_PER_SEC % HZ &&
+	    div_u64(n, NSEC_PER_SEC) >= MAX_JIFFY_OFFSET / HZ)
+		return MAX_JIFFY_OFFSET;
+
+	return min_t(u64, MAX_JIFFY_OFFSET, nsecs_to_jiffies64(n) + 1);
+}
+
+static unsigned long to_wait_timeout(s64 timeout_ns)
+{
+	if (timeout_ns < 0)
+		return MAX_SCHEDULE_TIMEOUT;
+
+	if (timeout_ns == 0)
+		return 0;
+
+	return nsecs_to_jiffies_timeout(timeout_ns);
+}
+
+/**
+ * i915_gem_wait_ioctl - implements DRM_IOCTL_I915_GEM_WAIT
+ * @dev: drm device pointer
+ * @data: ioctl data blob
+ * @file: drm file pointer
+ *
+ * Returns 0 if successful, else an error is returned with the remaining time in
+ * the timeout parameter.
+ *  -ETIME: object is still busy after timeout
+ *  -ERESTARTSYS: signal interrupted the wait
+ *  -ENONENT: object doesn't exist
+ * Also possible, but rare:
+ *  -EAGAIN: incomplete, restart syscall
+ *  -ENOMEM: damn
+ *  -ENODEV: Internal IRQ fail
+ *  -E?: The add request failed
+ *
+ * The wait ioctl with a timeout of 0 reimplements the busy ioctl. With any
+ * non-zero timeout parameter the wait ioctl will wait for the given number of
+ * nanoseconds on an object becoming unbusy. Since the wait itself does so
+ * without holding struct_mutex the object may become re-busied before this
+ * function completes. A similar but shorter * race condition exists in the busy
+ * ioctl
+ */
+int
+i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
+{
+	struct drm_i915_gem_wait *args = data;
+	struct drm_i915_gem_object *obj;
+	ktime_t start;
+	long ret;
+
+	if (args->flags != 0)
+		return -EINVAL;
+
+	obj = i915_gem_object_lookup(file, args->bo_handle);
+	if (!obj)
+		return -ENOENT;
+
+	start = ktime_get();
+
+	ret = i915_gem_object_wait(obj,
+				   I915_WAIT_INTERRUPTIBLE |
+				   I915_WAIT_PRIORITY |
+				   I915_WAIT_ALL,
+				   to_wait_timeout(args->timeout_ns));
+
+	if (args->timeout_ns > 0) {
+		args->timeout_ns -= ktime_to_ns(ktime_sub(ktime_get(), start));
+		if (args->timeout_ns < 0)
+			args->timeout_ns = 0;
+
+		/*
+		 * Apparently ktime isn't accurate enough and occasionally has a
+		 * bit of mismatch in the jiffies<->nsecs<->ktime loop. So patch
+		 * things up to make the test happy. We allow up to 1 jiffy.
+		 *
+		 * This is a regression from the timespec->ktime conversion.
+		 */
+		if (ret == -ETIME && !nsecs_to_jiffies(args->timeout_ns))
+			args->timeout_ns = 0;
+
+		/* Asked to wait beyond the jiffie/scheduler precision? */
+		if (ret == -ETIME && args->timeout_ns)
+			ret = -EAGAIN;
+	}
+
+	i915_gem_object_put(obj);
+	return ret;
+}