[Intel-gfx] [PATCH 12/62] drm/i915: Skip capturing an error state if we already have one

Chris Wilson chris at chris-wilson.co.uk
Fri Jun 3 16:36:37 UTC 2016


As we only ever keep the first error state around, we can avoid some
work that can be quite intrusive if we don't record the error the second
time around. This does move the race whereby the user could discard one
error state as the second is being captured, but that race exists in the
current code and we hope that recapturing error state is only done for
debugging.

Note that as we discard the error state for simulated errors, igt that
exercise error capture continue to function.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/Makefile           |   1 +
 drivers/gpu/drm/i915/i915_drv.h         | 210 +---------
 drivers/gpu/drm/i915/i915_gem.c         | 653 +------------------------------
 drivers/gpu/drm/i915/i915_gem_request.c | 659 ++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_gem_request.h | 245 ++++++++++++
 drivers/gpu/drm/i915/i915_gpu_error.c   |   3 +
 6 files changed, 916 insertions(+), 855 deletions(-)
 create mode 100644 drivers/gpu/drm/i915/i915_gem_request.c
 create mode 100644 drivers/gpu/drm/i915/i915_gem_request.h

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index f20007440821..14cef1d2343c 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -32,6 +32,7 @@ i915-y += i915_cmd_parser.o \
 	  i915_gem_gtt.o \
 	  i915_gem.o \
 	  i915_gem_render_state.o \
+	  i915_gem_request.o \
 	  i915_gem_shrinker.o \
 	  i915_gem_stolen.o \
 	  i915_gem_tiling.o \
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 15a0c6bdf500..939cd45043c7 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -60,6 +60,7 @@
 #include "i915_gem.h"
 #include "i915_gem_gtt.h"
 #include "i915_gem_render_state.h"
+#include "i915_gem_request.h"
 
 /* General customization:
  */
@@ -2339,172 +2340,6 @@ static inline struct scatterlist *__sg_next(struct scatterlist *sg)
 	     (((__iter).curr += PAGE_SIZE) < (__iter).max) ||		\
 	     ((__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0))
 
-/**
- * Request queue structure.
- *
- * The request queue allows us to note sequence numbers that have been emitted
- * and may be associated with active buffers to be retired.
- *
- * By keeping this list, we can avoid having to do questionable sequence
- * number comparisons on buffer last_read|write_seqno. It also allows an
- * emission time to be associated with the request for tracking how far ahead
- * of the GPU the submission is.
- *
- * The requests are reference counted, so upon creation they should have an
- * initial reference taken using kref_init
- */
-struct drm_i915_gem_request {
-	struct kref ref;
-
-	/** On Which ring this request was generated */
-	struct drm_i915_private *i915;
-	struct intel_engine_cs *engine;
-	unsigned reset_counter;
-	struct intel_signal_node signaling;
-
-	 /** GEM sequence number associated with the previous request,
-	  * when the HWS breadcrumb is equal to this the GPU is processing
-	  * this request.
-	  */
-	u32 previous_seqno;
-
-	 /** GEM sequence number associated with this request,
-	  * when the HWS breadcrumb is equal or greater than this the GPU
-	  * has finished processing this request.
-	  */
-	u32 seqno;
-
-	/** Position in the ringbuffer of the start of the request */
-	u32 head;
-
-	/**
-	 * Position in the ringbuffer of the start of the postfix.
-	 * This is required to calculate the maximum available ringbuffer
-	 * space without overwriting the postfix.
-	 */
-	 u32 postfix;
-
-	/** Position in the ringbuffer of the end of the whole request */
-	u32 tail;
-
-	/** Preallocate space in the ringbuffer for the emitting the request */
-	u32 reserved_space;
-
-	/**
-	 * Context and ring buffer related to this request
-	 * Contexts are refcounted, so when this request is associated with a
-	 * context, we must increment the context's refcount, to guarantee that
-	 * it persists while any request is linked to it. Requests themselves
-	 * are also refcounted, so the request will only be freed when the last
-	 * reference to it is dismissed, and the code in
-	 * i915_gem_request_free() will then decrement the refcount on the
-	 * context.
-	 */
-	struct i915_gem_context *ctx;
-	struct intel_ringbuffer *ringbuf;
-
-	/**
-	 * Context related to the previous request.
-	 * As the contexts are accessed by the hardware until the switch is
-	 * completed to a new context, the hardware may still be writing
-	 * to the context object after the breadcrumb is visible. We must
-	 * not unpin/unbind/prune that object whilst still active and so
-	 * we keep the previous context pinned until the following (this)
-	 * request is retired.
-	 */
-	struct i915_gem_context *previous_context;
-
-	/** Batch buffer related to this request if any (used for
-	    error state dump only) */
-	struct drm_i915_gem_object *batch_obj;
-
-	/** Time at which this request was emitted, in jiffies. */
-	unsigned long emitted_jiffies;
-
-	/** global list entry for this request */
-	struct list_head list;
-
-	struct drm_i915_file_private *file_priv;
-	/** file_priv list entry for this request */
-	struct list_head client_list;
-
-	/** process identifier submitting this request */
-	struct pid *pid;
-
-	/**
-	 * The ELSP only accepts two elements at a time, so we queue
-	 * context/tail pairs on a given queue (ring->execlist_queue) until the
-	 * hardware is available. The queue serves a double purpose: we also use
-	 * it to keep track of the up to 2 contexts currently in the hardware
-	 * (usually one in execution and the other queued up by the GPU): We
-	 * only remove elements from the head of the queue when the hardware
-	 * informs us that an element has been completed.
-	 *
-	 * All accesses to the queue are mediated by a spinlock
-	 * (ring->execlist_lock).
-	 */
-
-	/** Execlist link in the submission queue.*/
-	struct list_head execlist_link;
-
-	/** Execlists no. of times this request has been sent to the ELSP */
-	int elsp_submitted;
-
-	/** Execlists context hardware id. */
-	unsigned ctx_hw_id;
-};
-
-struct drm_i915_gem_request * __must_check
-i915_gem_request_alloc(struct intel_engine_cs *engine,
-		       struct i915_gem_context *ctx);
-void i915_gem_request_free(struct kref *req_ref);
-int i915_gem_request_add_to_client(struct drm_i915_gem_request *req,
-				   struct drm_file *file);
-
-static inline uint32_t
-i915_gem_request_get_seqno(struct drm_i915_gem_request *req)
-{
-	return req ? req->seqno : 0;
-}
-
-static inline struct intel_engine_cs *
-i915_gem_request_get_engine(struct drm_i915_gem_request *req)
-{
-	return req ? req->engine : NULL;
-}
-
-static inline struct drm_i915_gem_request *
-i915_gem_request_reference(struct drm_i915_gem_request *req)
-{
-	if (req)
-		kref_get(&req->ref);
-	return req;
-}
-
-static inline void
-i915_gem_request_unreference(struct drm_i915_gem_request *req)
-{
-	kref_put(&req->ref, i915_gem_request_free);
-}
-
-static inline void i915_gem_request_assign(struct drm_i915_gem_request **pdst,
-					   struct drm_i915_gem_request *src)
-{
-	if (src)
-		i915_gem_request_reference(src);
-
-	if (*pdst)
-		i915_gem_request_unreference(*pdst);
-
-	*pdst = src;
-}
-
-/*
- * XXX: i915_gem_request_completed should be here but currently needs the
- * definition of i915_seqno_passed() which is below. It will be moved in
- * a later patch when the call to i915_seqno_passed() is obsoleted...
- */
-
 /*
  * A command that requires special handling by the command parser.
  */
@@ -3208,37 +3043,6 @@ void i915_gem_track_fb(struct drm_i915_gem_object *old,
 		       struct drm_i915_gem_object *new,
 		       unsigned frontbuffer_bits);
 
-/**
- * Returns true if seq1 is later than seq2.
- */
-static inline bool
-i915_seqno_passed(uint32_t seq1, uint32_t seq2)
-{
-	return (int32_t)(seq1 - seq2) >= 0;
-}
-
-static inline bool i915_gem_request_started(const struct drm_i915_gem_request *req)
-{
-	return i915_seqno_passed(intel_engine_get_seqno(req->engine),
-				 req->previous_seqno);
-}
-
-static inline bool i915_gem_request_completed(const struct drm_i915_gem_request *req)
-{
-	return i915_seqno_passed(intel_engine_get_seqno(req->engine),
-				 req->seqno);
-}
-
-bool __i915_spin_request(const struct drm_i915_gem_request *request,
-			 int state, unsigned long timeout_us);
-static inline bool i915_spin_request(const struct drm_i915_gem_request *request,
-				     int state, unsigned long timeout_us)
-{
-	return (i915_gem_request_started(request) &&
-		__i915_spin_request(request, state, timeout_us));
-}
-
-int __must_check i915_gem_get_seqno(struct drm_i915_private *dev_priv, u32 *seqno);
 int __must_check i915_gem_set_seqno(struct drm_device *dev, u32 seqno);
 
 struct drm_i915_gem_request *
@@ -3296,18 +3100,6 @@ void i915_gem_init_swizzling(struct drm_device *dev);
 void i915_gem_cleanup_engines(struct drm_device *dev);
 int __must_check i915_gem_wait_for_idle(struct drm_i915_private *dev_priv);
 int __must_check i915_gem_suspend(struct drm_device *dev);
-void __i915_add_request(struct drm_i915_gem_request *req,
-			struct drm_i915_gem_object *batch_obj,
-			bool flush_caches);
-#define i915_add_request(req) \
-	__i915_add_request(req, NULL, true)
-#define i915_add_request_no_flush(req) \
-	__i915_add_request(req, NULL, false)
-int __i915_wait_request(struct drm_i915_gem_request *req,
-			bool interruptible,
-			s64 *timeout,
-			struct intel_rps_client *rps);
-int __must_check i915_wait_request(struct drm_i915_gem_request *req);
 int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf);
 int __must_check
 i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index f48f54193972..95782cf85dcc 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1105,361 +1105,6 @@ put_rpm:
 	return ret;
 }
 
-static int
-i915_gem_check_wedge(unsigned reset_counter, bool interruptible)
-{
-	if (__i915_terminally_wedged(reset_counter))
-		return -EIO;
-
-	if (__i915_reset_in_progress(reset_counter)) {
-		/* Non-interruptible callers can't handle -EAGAIN, hence return
-		 * -EIO unconditionally for these. */
-		if (!interruptible)
-			return -EIO;
-
-		return -EAGAIN;
-	}
-
-	return 0;
-}
-
-static unsigned long local_clock_us(unsigned *cpu)
-{
-	unsigned long t;
-
-	/* Cheaply and approximately convert from nanoseconds to microseconds.
-	 * The result and subsequent calculations are also defined in the same
-	 * approximate microseconds units. The principal source of timing
-	 * error here is from the simple truncation.
-	 *
-	 * Note that local_clock() is only defined wrt to the current CPU;
-	 * the comparisons are no longer valid if we switch CPUs. Instead of
-	 * blocking preemption for the entire busywait, we can detect the CPU
-	 * switch and use that as indicator of system load and a reason to
-	 * stop busywaiting, see busywait_stop().
-	 */
-	*cpu = get_cpu();
-	t = local_clock() >> 10;
-	put_cpu();
-
-	return t;
-}
-
-static bool busywait_stop(unsigned long timeout, unsigned cpu)
-{
-	unsigned this_cpu;
-
-	if (time_after(local_clock_us(&this_cpu), timeout))
-		return true;
-
-	return this_cpu != cpu;
-}
-
-bool __i915_spin_request(const struct drm_i915_gem_request *req,
-			 int state, unsigned long timeout_us)
-{
-	unsigned cpu;
-
-	/* When waiting for high frequency requests, e.g. during synchronous
-	 * rendering split between the CPU and GPU, the finite amount of time
-	 * required to set up the irq and wait upon it limits the response
-	 * rate. By busywaiting on the request completion for a short while we
-	 * can service the high frequency waits as quick as possible. However,
-	 * if it is a slow request, we want to sleep as quickly as possible.
-	 * The tradeoff between waiting and sleeping is roughly the time it
-	 * takes to sleep on a request, on the order of a microsecond.
-	 */
-
-	timeout_us += local_clock_us(&cpu);
-	do {
-		if (i915_gem_request_completed(req))
-			return true;
-
-		if (signal_pending_state(state, current))
-			break;
-
-		if (busywait_stop(timeout_us, cpu))
-			break;
-
-		cpu_relax_lowlatency();
-	} while (!need_resched());
-
-	return false;
-}
-
-/**
- * __i915_wait_request - wait until execution of request has finished
- * @req: duh!
- * @interruptible: do an interruptible wait (normally yes)
- * @timeout: in - how long to wait (NULL forever); out - how much time remaining
- *
- * Note: It is of utmost importance that the passed in seqno and reset_counter
- * values have been read by the caller in an smp safe manner. Where read-side
- * locks are involved, it is sufficient to read the reset_counter before
- * unlocking the lock that protects the seqno. For lockless tricks, the
- * reset_counter _must_ be read before, and an appropriate smp_rmb must be
- * inserted.
- *
- * Returns 0 if the request was found within the alloted time. Else returns the
- * errno with remaining time filled in timeout argument.
- */
-int __i915_wait_request(struct drm_i915_gem_request *req,
-			bool interruptible,
-			s64 *timeout,
-			struct intel_rps_client *rps)
-{
-	int state = interruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
-	DEFINE_WAIT(reset);
-	struct intel_wait wait;
-	unsigned long timeout_remain;
-	int ret = 0;
-
-	might_sleep();
-
-	if (list_empty(&req->list))
-		return 0;
-
-	if (i915_gem_request_completed(req))
-		return 0;
-
-	timeout_remain = MAX_SCHEDULE_TIMEOUT;
-	if (timeout) {
-		if (WARN_ON(*timeout < 0))
-			return -EINVAL;
-
-		if (*timeout == 0)
-			return -ETIME;
-
-		/* Record current time in case interrupted, or wedged */
-		timeout_remain = nsecs_to_jiffies_timeout(*timeout);
-		*timeout += ktime_get_raw_ns();
-	}
-
-	trace_i915_gem_request_wait_begin(req);
-
-	/* This client is about to stall waiting for the GPU. In many cases
-	 * this is undesirable and limits the throughput of the system, as
-	 * many clients cannot continue processing user input/output whilst
-	 * blocked. RPS autotuning may take tens of milliseconds to respond
-	 * to the GPU load and thus incurs additional latency for the client.
-	 * We can circumvent that by promoting the GPU frequency to maximum
-	 * before we wait. This makes the GPU throttle up much more quickly
-	 * (good for benchmarks and user experience, e.g. window animations),
-	 * but at a cost of spending more power processing the workload
-	 * (bad for battery). Not all clients even want their results
-	 * immediately and for them we should just let the GPU select its own
-	 * frequency to maximise efficiency. To prevent a single client from
-	 * forcing the clocks too high for the whole system, we only allow
-	 * each client to waitboost once in a busy period.
-	 */
-	if (INTEL_INFO(req->i915)->gen >= 6)
-		gen6_rps_boost(req->i915, rps, req->emitted_jiffies);
-
-	/* Optimistic spin for the next ~jiffie before touching IRQs */
-	if (i915_spin_request(req, state, 5))
-		goto complete;
-
-	intel_wait_init(&wait, req->seqno);
-	set_current_state(state);
-	if (intel_engine_add_wait(req->engine, &wait))
-		/* In order to check that we haven't missed the interrupt
-		 * as we enabled it, we need to kick ourselves to do a
-		 * coherent check on the seqno before we sleep.
-		 */
-		goto wakeup;
-
-	add_wait_queue(&req->i915->gpu_error.wait_queue, &reset);
-	for (;;) {
-		if (signal_pending_state(state, current)) {
-			ret = -ERESTARTSYS;
-			break;
-		}
-
-		/* Ensure that even if the GPU hangs, we get woken up. */
-		i915_queue_hangcheck(req->i915);
-
-		timeout_remain = io_schedule_timeout(timeout_remain);
-		if (timeout_remain == 0) {
-			ret = -ETIME;
-			break;
-		}
-
-		if (intel_wait_complete(&wait))
-			break;
-
-wakeup:
-		set_current_state(state);
-
-		/* Carefully check if the request is complete, giving time
-		 * for the seqno to be visible following the interrupt.
-		 * We also have to check in case we are kicked by the GPU
-		 * reset in order to drop the struct_mutex.
-		 */
-		if (__i915_request_irq_complete(req))
-			break;
-
-		/* Only spin if we know the GPU is processing this request */
-		if (i915_spin_request(req, state, 2))
-			break;
-	}
-	remove_wait_queue(&req->i915->gpu_error.wait_queue, &reset);
-
-	intel_engine_remove_wait(req->engine, &wait);
-	__set_current_state(TASK_RUNNING);
-complete:
-	trace_i915_gem_request_wait_end(req);
-
-	if (timeout) {
-		*timeout -= ktime_get_raw_ns();
-		if (*timeout < 0)
-			*timeout = 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 regrssion from the timespec->ktime conversion.
-		 */
-		if (ret == -ETIME && *timeout < jiffies_to_usecs(1)*1000)
-			*timeout = 0;
-	}
-
-	if (rps && req->seqno == req->engine->last_submitted_seqno) {
-		/* The GPU is now idle and this client has stalled.
-		 * Since no other client has submitted a request in the
-		 * meantime, assume that this client is the only one
-		 * supplying work to the GPU but is unable to keep that
-		 * work supplied because it is waiting. Since the GPU is
-		 * then never kept fully busy, RPS autoclocking will
-		 * keep the clocks relatively low, causing further delays.
-		 * Compensate by giving the synchronous client credit for
-		 * a waitboost next time.
-		 */
-		spin_lock(&req->i915->rps.client_lock);
-		list_del_init(&rps->link);
-		spin_unlock(&req->i915->rps.client_lock);
-	}
-
-	return ret;
-}
-
-int i915_gem_request_add_to_client(struct drm_i915_gem_request *req,
-				   struct drm_file *file)
-{
-	struct drm_i915_file_private *file_priv;
-
-	WARN_ON(!req || !file || req->file_priv);
-
-	if (!req || !file)
-		return -EINVAL;
-
-	if (req->file_priv)
-		return -EINVAL;
-
-	file_priv = file->driver_priv;
-
-	spin_lock(&file_priv->mm.lock);
-	req->file_priv = file_priv;
-	list_add_tail(&req->client_list, &file_priv->mm.request_list);
-	spin_unlock(&file_priv->mm.lock);
-
-	req->pid = get_pid(task_pid(current));
-
-	return 0;
-}
-
-static inline void
-i915_gem_request_remove_from_client(struct drm_i915_gem_request *request)
-{
-	struct drm_i915_file_private *file_priv = request->file_priv;
-
-	if (!file_priv)
-		return;
-
-	spin_lock(&file_priv->mm.lock);
-	list_del(&request->client_list);
-	request->file_priv = NULL;
-	spin_unlock(&file_priv->mm.lock);
-
-	put_pid(request->pid);
-	request->pid = NULL;
-}
-
-static void i915_gem_request_retire(struct drm_i915_gem_request *request)
-{
-	trace_i915_gem_request_retire(request);
-
-	/* We know the GPU must have read the request to have
-	 * sent us the seqno + interrupt, so use the position
-	 * of tail of the request to update the last known position
-	 * of the GPU head.
-	 *
-	 * Note this requires that we are always called in request
-	 * completion order.
-	 */
-	request->ringbuf->last_retired_head = request->postfix;
-
-	list_del_init(&request->list);
-	i915_gem_request_remove_from_client(request);
-
-	if (request->previous_context) {
-		if (i915.enable_execlists)
-			intel_lr_context_unpin(request->previous_context,
-					       request->engine);
-	}
-
-	i915_gem_context_unreference(request->ctx);
-	i915_gem_request_unreference(request);
-}
-
-static void
-__i915_gem_request_retire__upto(struct drm_i915_gem_request *req)
-{
-	struct intel_engine_cs *engine = req->engine;
-	struct drm_i915_gem_request *tmp;
-
-	lockdep_assert_held(&engine->i915->dev->struct_mutex);
-
-	if (list_empty(&req->list))
-		return;
-
-	do {
-		tmp = list_first_entry(&engine->request_list,
-				       typeof(*tmp), list);
-
-		i915_gem_request_retire(tmp);
-	} while (tmp != req);
-
-	WARN_ON(i915_verify_lists(engine->dev));
-}
-
-/**
- * Waits for a request to be signaled, and cleans up the
- * request and object lists appropriately for that event.
- */
-int
-i915_wait_request(struct drm_i915_gem_request *req)
-{
-	struct drm_i915_private *dev_priv = req->i915;
-	bool interruptible;
-	int ret;
-
-	interruptible = dev_priv->mm.interruptible;
-
-	BUG_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
-
-	ret = __i915_wait_request(req, interruptible, NULL, NULL);
-	if (ret)
-		return ret;
-
-	/* If the GPU hung, we want to keep the requests to find the guilty. */
-	if (req->reset_counter == i915_reset_counter(&dev_priv->gpu_error))
-		__i915_gem_request_retire__upto(req);
-
-	return 0;
-}
-
 /**
  * Ensures that all rendering to the object has completed and the object is
  * safe to unbind from the GTT or access from the CPU.
@@ -1514,7 +1159,7 @@ i915_gem_object_retire_request(struct drm_i915_gem_object *obj,
 		i915_gem_object_retire__write(obj);
 
 	if (req->reset_counter == i915_reset_counter(&req->i915->gpu_error))
-		__i915_gem_request_retire__upto(req);
+		i915_gem_request_retire_upto(req);
 }
 
 /* A nonblocking variant of the above wait. This is a highly dangerous routine
@@ -2515,194 +2160,6 @@ i915_gem_object_retire__read(struct drm_i915_gem_object *obj, int ring)
 	drm_gem_object_unreference(&obj->base);
 }
 
-static int
-i915_gem_init_seqno(struct drm_i915_private *dev_priv, u32 seqno)
-{
-	struct intel_engine_cs *engine;
-	int ret;
-
-	/* Carefully retire all requests without writing to the rings */
-	for_each_engine(engine, dev_priv) {
-		ret = intel_engine_idle(engine);
-		if (ret)
-			return ret;
-	}
-	i915_gem_retire_requests(dev_priv);
-
-	/* If the seqno wraps around, we need to clear the breadcrumb rbtree */
-	if (!i915_seqno_passed(seqno, dev_priv->next_seqno)) {
-		while (intel_kick_waiters(dev_priv) ||
-		       intel_kick_signalers(dev_priv))
-			yield();
-	}
-
-	/* Finally reset hw state */
-	for_each_engine(engine, dev_priv)
-		intel_ring_init_seqno(engine, seqno);
-
-	return 0;
-}
-
-int i915_gem_set_seqno(struct drm_device *dev, u32 seqno)
-{
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	int ret;
-
-	if (seqno == 0)
-		return -EINVAL;
-
-	/* HWS page needs to be set less than what we
-	 * will inject to ring
-	 */
-	ret = i915_gem_init_seqno(dev_priv, seqno - 1);
-	if (ret)
-		return ret;
-
-	/* Carefully set the last_seqno value so that wrap
-	 * detection still works
-	 */
-	dev_priv->next_seqno = seqno;
-	dev_priv->last_seqno = seqno - 1;
-	if (dev_priv->last_seqno == 0)
-		dev_priv->last_seqno--;
-
-	return 0;
-}
-
-int
-i915_gem_get_seqno(struct drm_i915_private *dev_priv, u32 *seqno)
-{
-	/* reserve 0 for non-seqno */
-	if (dev_priv->next_seqno == 0) {
-		int ret = i915_gem_init_seqno(dev_priv, 0);
-		if (ret)
-			return ret;
-
-		dev_priv->next_seqno = 1;
-	}
-
-	*seqno = dev_priv->last_seqno = dev_priv->next_seqno++;
-	return 0;
-}
-
-static void i915_gem_mark_busy(struct drm_i915_private *dev_priv,
-			       const struct intel_engine_cs *engine)
-{
-	dev_priv->gt.active_engines |= intel_engine_flag(engine);
-	if (dev_priv->gt.awake)
-		return;
-
-	intel_runtime_pm_get_noresume(dev_priv);
-	dev_priv->gt.awake = true;
-
-	intel_enable_gt_powersave(dev_priv);
-	i915_update_gfx_val(dev_priv);
-	if (INTEL_INFO(dev_priv)->gen >= 6)
-		gen6_rps_busy(dev_priv);
-
-	queue_delayed_work(dev_priv->wq,
-			   &dev_priv->gt.retire_work,
-			   round_jiffies_up_relative(HZ));
-}
-
-/*
- * NB: This function is not allowed to fail. Doing so would mean the the
- * request is not being tracked for completion but the work itself is
- * going to happen on the hardware. This would be a Bad Thing(tm).
- */
-void __i915_add_request(struct drm_i915_gem_request *request,
-			struct drm_i915_gem_object *obj,
-			bool flush_caches)
-{
-	struct intel_engine_cs *engine;
-	struct drm_i915_private *dev_priv;
-	struct intel_ringbuffer *ringbuf;
-	u32 request_start;
-	u32 reserved_tail;
-	int ret;
-
-	if (WARN_ON(request == NULL))
-		return;
-
-	engine = request->engine;
-	dev_priv = request->i915;
-	ringbuf = request->ringbuf;
-
-	/*
-	 * To ensure that this call will not fail, space for its emissions
-	 * should already have been reserved in the ring buffer. Let the ring
-	 * know that it is time to use that space up.
-	 */
-	request_start = intel_ring_get_tail(ringbuf);
-	reserved_tail = request->reserved_space;
-	request->reserved_space = 0;
-
-	/*
-	 * Emit any outstanding flushes - execbuf can fail to emit the flush
-	 * after having emitted the batchbuffer command. Hence we need to fix
-	 * things up similar to emitting the lazy request. The difference here
-	 * is that the flush _must_ happen before the next request, no matter
-	 * what.
-	 */
-	if (flush_caches) {
-		if (i915.enable_execlists)
-			ret = logical_ring_flush_all_caches(request);
-		else
-			ret = intel_ring_flush_all_caches(request);
-		/* Not allowed to fail! */
-		WARN(ret, "*_ring_flush_all_caches failed: %d!\n", ret);
-	}
-
-	trace_i915_gem_request_add(request);
-
-	request->head = request_start;
-
-	/* Whilst this request exists, batch_obj will be on the
-	 * active_list, and so will hold the active reference. Only when this
-	 * request is retired will the the batch_obj be moved onto the
-	 * inactive_list and lose its active reference. Hence we do not need
-	 * to explicitly hold another reference here.
-	 */
-	request->batch_obj = obj;
-
-	/* Seal the request and mark it as pending execution. Note that
-	 * we may inspect this state, without holding any locks, during
-	 * hangcheck. Hence we apply the barrier to ensure that we do not
-	 * see a more recent value in the hws than we are tracking.
-	 */
-	request->emitted_jiffies = jiffies;
-	request->previous_seqno = engine->last_submitted_seqno;
-	smp_store_mb(engine->last_submitted_seqno, request->seqno);
-	list_add_tail(&request->list, &engine->request_list);
-
-	/* Record the position of the start of the request so that
-	 * should we detect the updated seqno part-way through the
-	 * GPU processing the request, we never over-estimate the
-	 * position of the head.
-	 */
-	request->postfix = intel_ring_get_tail(ringbuf);
-
-	if (i915.enable_execlists)
-		ret = engine->emit_request(request);
-	else {
-		ret = engine->add_request(request);
-
-		request->tail = intel_ring_get_tail(ringbuf);
-	}
-	/* Not allowed to fail! */
-	WARN(ret, "emit|add_request failed: %d!\n", ret);
-	/* Sanity check that the reserved size was large enough. */
-	ret = intel_ring_get_tail(ringbuf) - request_start;
-	if (ret < 0)
-		ret += ringbuf->size;
-	WARN_ONCE(ret > reserved_tail,
-		  "Not enough space reserved (%d bytes) "
-		  "for adding the request (%d bytes)\n",
-		  reserved_tail, ret);
-
-	i915_gem_mark_busy(dev_priv, engine);
-}
-
 static bool i915_context_is_banned(const struct i915_gem_context *ctx)
 {
 	unsigned long elapsed;
@@ -2734,102 +2191,6 @@ static void i915_set_reset_status(struct i915_gem_context *ctx,
 	}
 }
 
-void i915_gem_request_free(struct kref *req_ref)
-{
-	struct drm_i915_gem_request *req = container_of(req_ref,
-						 typeof(*req), ref);
-	kmem_cache_free(req->i915->requests, req);
-}
-
-static inline int
-__i915_gem_request_alloc(struct intel_engine_cs *engine,
-			 struct i915_gem_context *ctx,
-			 struct drm_i915_gem_request **req_out)
-{
-	struct drm_i915_private *dev_priv = engine->i915;
-	unsigned reset_counter = i915_reset_counter(&dev_priv->gpu_error);
-	struct drm_i915_gem_request *req;
-	int ret;
-
-	if (!req_out)
-		return -EINVAL;
-
-	*req_out = NULL;
-
-	/* ABI: Before userspace accesses the GPU (e.g. execbuffer), report
-	 * EIO if the GPU is already wedged, or EAGAIN to drop the struct_mutex
-	 * and restart.
-	 */
-	ret = i915_gem_check_wedge(reset_counter, dev_priv->mm.interruptible);
-	if (ret)
-		return ret;
-
-	req = kmem_cache_zalloc(dev_priv->requests, GFP_KERNEL);
-	if (req == NULL)
-		return -ENOMEM;
-
-	ret = i915_gem_get_seqno(engine->i915, &req->seqno);
-	if (ret)
-		goto err;
-
-	kref_init(&req->ref);
-	req->i915 = dev_priv;
-	req->engine = engine;
-	req->reset_counter = reset_counter;
-	req->ctx  = ctx;
-	i915_gem_context_reference(req->ctx);
-
-	/*
-	 * Reserve space in the ring buffer for all the commands required to
-	 * eventually emit this request. This is to guarantee that the
-	 * i915_add_request() call can't fail. Note that the reserve may need
-	 * to be redone if the request is not actually submitted straight
-	 * away, e.g. because a GPU scheduler has deferred it.
-	 */
-	req->reserved_space = MIN_SPACE_FOR_ADD_REQUEST;
-
-	if (i915.enable_execlists)
-		ret = intel_logical_ring_alloc_request_extras(req);
-	else
-		ret = intel_ring_alloc_request_extras(req);
-	if (ret)
-		goto err_ctx;
-
-	*req_out = req;
-	return 0;
-
-err_ctx:
-	i915_gem_context_unreference(ctx);
-err:
-	kmem_cache_free(dev_priv->requests, req);
-	return ret;
-}
-
-/**
- * i915_gem_request_alloc - allocate a request structure
- *
- * @engine: engine that we wish to issue the request on.
- * @ctx: context that the request will be associated with.
- *       This can be NULL if the request is not directly related to
- *       any specific user context, in which case this function will
- *       choose an appropriate context to use.
- *
- * Returns a pointer to the allocated request if successful,
- * or an error code if not.
- */
-struct drm_i915_gem_request *
-i915_gem_request_alloc(struct intel_engine_cs *engine,
-		       struct i915_gem_context *ctx)
-{
-	struct drm_i915_gem_request *req;
-	int err;
-
-	if (ctx == NULL)
-		ctx = engine->i915->kernel_context;
-	err = __i915_gem_request_alloc(engine, ctx, &req);
-	return err ? ERR_PTR(err) : req;
-}
-
 struct drm_i915_gem_request *
 i915_gem_find_active_request(struct intel_engine_cs *engine)
 {
@@ -2903,14 +2264,14 @@ static void i915_gem_reset_engine_cleanup(struct intel_engine_cs *engine)
 	 * implicit references on things like e.g. ppgtt address spaces through
 	 * the request.
 	 */
-	while (!list_empty(&engine->request_list)) {
+	if (!list_empty(&engine->request_list)) {
 		struct drm_i915_gem_request *request;
 
-		request = list_first_entry(&engine->request_list,
-					   struct drm_i915_gem_request,
-					   list);
+		request = list_last_entry(&engine->request_list,
+					  struct drm_i915_gem_request,
+					  list);
 
-		i915_gem_request_retire(request);
+		i915_gem_request_retire_upto(request);
 	}
 
 	/* Having flushed all requests from all queues, we know that all
@@ -2974,7 +2335,7 @@ i915_gem_retire_requests_ring(struct intel_engine_cs *engine)
 		if (!i915_gem_request_completed(request))
 			break;
 
-		i915_gem_request_retire(request);
+		i915_gem_request_retire_upto(request);
 	}
 
 	/* Move any buffers on the active list that are no longer referenced
diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
new file mode 100644
index 000000000000..34b2f151cdfc
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -0,0 +1,659 @@
+/*
+ * Copyright © 2008-2015 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#include "i915_drv.h"
+
+static int i915_gem_check_wedge(unsigned reset_counter, bool interruptible)
+{
+	if (__i915_terminally_wedged(reset_counter))
+		return -EIO;
+
+	if (__i915_reset_in_progress(reset_counter)) {
+		/* Non-interruptible callers can't handle -EAGAIN, hence return
+		 * -EIO unconditionally for these. */
+		if (!interruptible)
+			return -EIO;
+
+		return -EAGAIN;
+	}
+
+	return 0;
+}
+
+static int i915_gem_init_seqno(struct drm_i915_private *dev_priv, u32 seqno)
+{
+	struct intel_engine_cs *engine;
+	int ret;
+
+	/* Carefully retire all requests without writing to the rings */
+	for_each_engine(engine, dev_priv) {
+		ret = intel_engine_idle(engine);
+		if (ret)
+			return ret;
+	}
+	i915_gem_retire_requests(dev_priv);
+
+	/* If the seqno wraps around, we need to clear the breadcrumb rbtree */
+	if (!i915_seqno_passed(seqno, dev_priv->next_seqno)) {
+		while (intel_kick_waiters(dev_priv) ||
+		       intel_kick_signalers(dev_priv))
+			yield();
+	}
+
+	/* Finally reset hw state */
+	for_each_engine(engine, dev_priv)
+		intel_ring_init_seqno(engine, seqno);
+
+	return 0;
+}
+
+int i915_gem_set_seqno(struct drm_device *dev, u32 seqno)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	int ret;
+
+	if (seqno == 0)
+		return -EINVAL;
+
+	/* HWS page needs to be set less than what we
+	 * will inject to ring
+	 */
+	ret = i915_gem_init_seqno(dev_priv, seqno - 1);
+	if (ret)
+		return ret;
+
+	/* Carefully set the last_seqno value so that wrap
+	 * detection still works
+	 */
+	dev_priv->next_seqno = seqno;
+	dev_priv->last_seqno = seqno - 1;
+	if (dev_priv->last_seqno == 0)
+		dev_priv->last_seqno--;
+
+	return 0;
+}
+
+static int i915_gem_get_seqno(struct drm_i915_private *dev_priv, u32 *seqno)
+{
+	/* reserve 0 for non-seqno */
+	if (unlikely(dev_priv->next_seqno == 0)) {
+		int ret = i915_gem_init_seqno(dev_priv, 0);
+		if (ret)
+			return ret;
+
+		dev_priv->next_seqno = 1;
+	}
+
+	*seqno = dev_priv->last_seqno = dev_priv->next_seqno++;
+	return 0;
+}
+
+static inline int
+__i915_gem_request_alloc(struct intel_engine_cs *engine,
+			 struct i915_gem_context *ctx,
+			 struct drm_i915_gem_request **req_out)
+{
+	struct drm_i915_private *dev_priv = engine->i915;
+	unsigned reset_counter = i915_reset_counter(&dev_priv->gpu_error);
+	struct drm_i915_gem_request *req;
+	int ret;
+
+	if (!req_out)
+		return -EINVAL;
+
+	*req_out = NULL;
+
+	/* ABI: Before userspace accesses the GPU (e.g. execbuffer), report
+	 * EIO if the GPU is already wedged, or EAGAIN to drop the struct_mutex
+	 * and restart.
+	 */
+	ret = i915_gem_check_wedge(reset_counter, dev_priv->mm.interruptible);
+	if (ret)
+		return ret;
+
+	req = kmem_cache_zalloc(dev_priv->requests, GFP_KERNEL);
+	if (req == NULL)
+		return -ENOMEM;
+
+	ret = i915_gem_get_seqno(dev_priv, &req->seqno);
+	if (ret)
+		goto err;
+
+	kref_init(&req->ref);
+	req->i915 = dev_priv;
+	req->engine = engine;
+	req->reset_counter = reset_counter;
+	req->ctx = ctx;
+	i915_gem_context_reference(ctx);
+
+	/*
+	 * Reserve space in the ring buffer for all the commands required to
+	 * eventually emit this request. This is to guarantee that the
+	 * i915_add_request() call can't fail. Note that the reserve may need
+	 * to be redone if the request is not actually submitted straight
+	 * away, e.g. because a GPU scheduler has deferred it.
+	 */
+	req->reserved_space = MIN_SPACE_FOR_ADD_REQUEST;
+
+	if (i915.enable_execlists)
+		ret = intel_logical_ring_alloc_request_extras(req);
+	else
+		ret = intel_ring_alloc_request_extras(req);
+	if (ret)
+		goto err_ctx;
+
+	*req_out = req;
+	return 0;
+
+err_ctx:
+	i915_gem_context_unreference(ctx);
+err:
+	kmem_cache_free(dev_priv->requests, req);
+	return ret;
+}
+
+/**
+ * i915_gem_request_alloc - allocate a request structure
+ *
+ * @engine: engine that we wish to issue the request on.
+ * @ctx: context that the request will be associated with.
+ *       This can be NULL if the request is not directly related to
+ *       any specific user context, in which case this function will
+ *       choose an appropriate context to use.
+ *
+ * Returns a pointer to the allocated request if successful,
+ * or an error code if not.
+ */
+struct drm_i915_gem_request *
+i915_gem_request_alloc(struct intel_engine_cs *engine,
+		       struct i915_gem_context *ctx)
+{
+	struct drm_i915_gem_request *req;
+	int err;
+
+	if (ctx == NULL)
+		ctx = engine->i915->kernel_context;
+	err = __i915_gem_request_alloc(engine, ctx, &req);
+	return err ? ERR_PTR(err) : req;
+}
+
+int i915_gem_request_add_to_client(struct drm_i915_gem_request *req,
+				   struct drm_file *file)
+{
+	struct drm_i915_private *dev_private;
+	struct drm_i915_file_private *file_priv;
+
+	WARN_ON(!req || !file || req->file_priv);
+
+	if (!req || !file)
+		return -EINVAL;
+
+	if (req->file_priv)
+		return -EINVAL;
+
+	dev_private = req->i915;
+	file_priv = file->driver_priv;
+
+	spin_lock(&file_priv->mm.lock);
+	req->file_priv = file_priv;
+	list_add_tail(&req->client_list, &file_priv->mm.request_list);
+	spin_unlock(&file_priv->mm.lock);
+
+	req->pid = get_pid(task_pid(current));
+
+	return 0;
+}
+
+static inline void
+i915_gem_request_remove_from_client(struct drm_i915_gem_request *request)
+{
+	struct drm_i915_file_private *file_priv = request->file_priv;
+
+	if (!file_priv)
+		return;
+
+	spin_lock(&file_priv->mm.lock);
+	list_del(&request->client_list);
+	request->file_priv = NULL;
+	spin_unlock(&file_priv->mm.lock);
+
+	put_pid(request->pid);
+	request->pid = NULL;
+}
+
+static void i915_gem_request_retire(struct drm_i915_gem_request *request)
+{
+	trace_i915_gem_request_retire(request);
+	list_del_init(&request->list);
+
+	/* We know the GPU must have read the request to have
+	 * sent us the seqno + interrupt, so use the position
+	 * of tail of the request to update the last known position
+	 * of the GPU head.
+	 *
+	 * Note this requires that we are always called in request
+	 * completion order.
+	 */
+	request->ringbuf->last_retired_head = request->postfix;
+
+	i915_gem_request_remove_from_client(request);
+
+	if (request->previous_context) {
+		if (i915.enable_execlists)
+			intel_lr_context_unpin(request->previous_context,
+					       request->engine);
+	}
+
+	i915_gem_context_unreference(request->ctx);
+	i915_gem_request_unreference(request);
+}
+
+void i915_gem_request_retire_upto(struct drm_i915_gem_request *req)
+{
+	struct intel_engine_cs *engine = req->engine;
+	struct drm_i915_gem_request *tmp;
+
+	lockdep_assert_held(&req->i915->dev->struct_mutex);
+
+	if (list_empty(&req->list))
+		return;
+
+	do {
+		tmp = list_first_entry(&engine->request_list,
+				       typeof(*tmp), list);
+
+		i915_gem_request_retire(tmp);
+	} while (tmp != req);
+
+	WARN_ON(i915_verify_lists(engine->dev));
+}
+
+static void i915_gem_mark_busy(struct drm_i915_private *dev_priv,
+			       const struct intel_engine_cs *engine)
+{
+	dev_priv->gt.active_engines |= intel_engine_flag(engine);
+	if (dev_priv->gt.awake)
+		return;
+
+	intel_runtime_pm_get_noresume(dev_priv);
+	dev_priv->gt.awake = true;
+
+	intel_enable_gt_powersave(dev_priv);
+	i915_update_gfx_val(dev_priv);
+	if (INTEL_INFO(dev_priv)->gen >= 6)
+		gen6_rps_busy(dev_priv);
+
+	queue_delayed_work(dev_priv->wq,
+			   &dev_priv->gt.retire_work,
+			   round_jiffies_up_relative(HZ));
+}
+
+/*
+ * NB: This function is not allowed to fail. Doing so would mean the the
+ * request is not being tracked for completion but the work itself is
+ * going to happen on the hardware. This would be a Bad Thing(tm).
+ */
+void __i915_add_request(struct drm_i915_gem_request *request,
+			struct drm_i915_gem_object *obj,
+			bool flush_caches)
+{
+	struct intel_engine_cs *engine;
+	struct drm_i915_private *dev_priv;
+	struct intel_ringbuffer *ringbuf;
+	u32 request_start;
+	u32 reserved_tail;
+	int ret;
+
+	if (WARN_ON(request == NULL))
+		return;
+
+	engine = request->engine;
+	dev_priv = request->i915;
+	ringbuf = request->ringbuf;
+
+	/*
+	 * To ensure that this call will not fail, space for its emissions
+	 * should already have been reserved in the ring buffer. Let the ring
+	 * know that it is time to use that space up.
+	 */
+	request_start = intel_ring_get_tail(ringbuf);
+	reserved_tail = request->reserved_space;
+	request->reserved_space = 0;
+
+	/*
+	 * Emit any outstanding flushes - execbuf can fail to emit the flush
+	 * after having emitted the batchbuffer command. Hence we need to fix
+	 * things up similar to emitting the lazy request. The difference here
+	 * is that the flush _must_ happen before the next request, no matter
+	 * what.
+	 */
+	if (flush_caches) {
+		if (i915.enable_execlists)
+			ret = logical_ring_flush_all_caches(request);
+		else
+			ret = intel_ring_flush_all_caches(request);
+		/* Not allowed to fail! */
+		WARN(ret, "*_ring_flush_all_caches failed: %d!\n", ret);
+	}
+
+	trace_i915_gem_request_add(request);
+
+	request->head = request_start;
+
+	/* Whilst this request exists, batch_obj will be on the
+	 * active_list, and so will hold the active reference. Only when this
+	 * request is retired will the the batch_obj be moved onto the
+	 * inactive_list and lose its active reference. Hence we do not need
+	 * to explicitly hold another reference here.
+	 */
+	request->batch_obj = obj;
+
+	/* Seal the request and mark it as pending execution. Note that
+	 * we may inspect this state, without holding any locks, during
+	 * hangcheck. Hence we apply the barrier to ensure that we do not
+	 * see a more recent value in the hws than we are tracking.
+	 */
+	request->emitted_jiffies = jiffies;
+	request->previous_seqno = engine->last_submitted_seqno;
+	smp_store_mb(engine->last_submitted_seqno, request->seqno);
+	list_add_tail(&request->list, &engine->request_list);
+
+	/* Record the position of the start of the request so that
+	 * should we detect the updated seqno part-way through the
+	 * GPU processing the request, we never over-estimate the
+	 * position of the head.
+	 */
+	request->postfix = intel_ring_get_tail(ringbuf);
+
+	if (i915.enable_execlists)
+		ret = engine->emit_request(request);
+	else {
+		ret = engine->add_request(request);
+
+		request->tail = intel_ring_get_tail(ringbuf);
+	}
+	/* Not allowed to fail! */
+	WARN(ret, "emit|add_request failed: %d!\n", ret);
+	/* Sanity check that the reserved size was large enough. */
+	ret = intel_ring_get_tail(ringbuf) - request_start;
+	if (ret < 0)
+		ret += ringbuf->size;
+	WARN_ONCE(ret > reserved_tail,
+		  "Not enough space reserved (%d bytes) "
+		  "for adding the request (%d bytes)\n",
+		  reserved_tail, ret);
+
+	i915_gem_mark_busy(dev_priv, engine);
+}
+
+static unsigned long local_clock_us(unsigned *cpu)
+{
+	unsigned long t;
+
+	/* Cheaply and approximately convert from nanoseconds to microseconds.
+	 * The result and subsequent calculations are also defined in the same
+	 * approximate microseconds units. The principal source of timing
+	 * error here is from the simple truncation.
+	 *
+	 * Note that local_clock() is only defined wrt to the current CPU;
+	 * the comparisons are no longer valid if we switch CPUs. Instead of
+	 * blocking preemption for the entire busywait, we can detect the CPU
+	 * switch and use that as indicator of system load and a reason to
+	 * stop busywaiting, see busywait_stop().
+	 */
+	*cpu = get_cpu();
+	t = local_clock() >> 10;
+	put_cpu();
+
+	return t;
+}
+
+static bool busywait_stop(unsigned long timeout, unsigned cpu)
+{
+	unsigned this_cpu;
+
+	if (time_after(local_clock_us(&this_cpu), timeout))
+		return true;
+
+	return this_cpu != cpu;
+}
+
+bool __i915_spin_request(const struct drm_i915_gem_request *req,
+			 int state, unsigned long timeout_us)
+{
+	unsigned cpu;
+
+	/* When waiting for high frequency requests, e.g. during synchronous
+	 * rendering split between the CPU and GPU, the finite amount of time
+	 * required to set up the irq and wait upon it limits the response
+	 * rate. By busywaiting on the request completion for a short while we
+	 * can service the high frequency waits as quick as possible. However,
+	 * if it is a slow request, we want to sleep as quickly as possible.
+	 * The tradeoff between waiting and sleeping is roughly the time it
+	 * takes to sleep on a request, on the order of a microsecond.
+	 */
+
+	timeout_us += local_clock_us(&cpu);
+	do {
+		if (i915_gem_request_completed(req))
+			return true;
+
+		if (signal_pending_state(state, current))
+			break;
+
+		if (busywait_stop(timeout_us, cpu))
+			break;
+
+		cpu_relax_lowlatency();
+	} while (!need_resched());
+
+	return false;
+}
+
+/**
+ * __i915_wait_request - wait until execution of request has finished
+ * @req: duh!
+ * @interruptible: do an interruptible wait (normally yes)
+ * @timeout: in - how long to wait (NULL forever); out - how much time remaining
+ *
+ * Note: It is of utmost importance that the passed in seqno and reset_counter
+ * values have been read by the caller in an smp safe manner. Where read-side
+ * locks are involved, it is sufficient to read the reset_counter before
+ * unlocking the lock that protects the seqno. For lockless tricks, the
+ * reset_counter _must_ be read before, and an appropriate smp_rmb must be
+ * inserted.
+ *
+ * Returns 0 if the request was found within the alloted time. Else returns the
+ * errno with remaining time filled in timeout argument.
+ */
+int __i915_wait_request(struct drm_i915_gem_request *req,
+			bool interruptible,
+			s64 *timeout,
+			struct intel_rps_client *rps)
+{
+	int state = interruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
+	DEFINE_WAIT(reset);
+	struct intel_wait wait;
+	unsigned long timeout_remain;
+	int ret = 0;
+
+	might_sleep();
+
+	if (list_empty(&req->list))
+		return 0;
+
+	if (i915_gem_request_completed(req))
+		return 0;
+
+	timeout_remain = MAX_SCHEDULE_TIMEOUT;
+	if (timeout) {
+		if (WARN_ON(*timeout < 0))
+			return -EINVAL;
+
+		if (*timeout == 0)
+			return -ETIME;
+
+		/* Record current time in case interrupted, or wedged */
+		timeout_remain = nsecs_to_jiffies_timeout(*timeout);
+		*timeout += ktime_get_raw_ns();
+	}
+
+	trace_i915_gem_request_wait_begin(req);
+
+	/* This client is about to stall waiting for the GPU. In many cases
+	 * this is undesirable and limits the throughput of the system, as
+	 * many clients cannot continue processing user input/output whilst
+	 * blocked. RPS autotuning may take tens of milliseconds to respond
+	 * to the GPU load and thus incurs additional latency for the client.
+	 * We can circumvent that by promoting the GPU frequency to maximum
+	 * before we wait. This makes the GPU throttle up much more quickly
+	 * (good for benchmarks and user experience, e.g. window animations),
+	 * but at a cost of spending more power processing the workload
+	 * (bad for battery). Not all clients even want their results
+	 * immediately and for them we should just let the GPU select its own
+	 * frequency to maximise efficiency. To prevent a single client from
+	 * forcing the clocks too high for the whole system, we only allow
+	 * each client to waitboost once in a busy period.
+	 */
+	if (INTEL_INFO(req->i915)->gen >= 6)
+		gen6_rps_boost(req->i915, rps, req->emitted_jiffies);
+
+	/* Optimistic spin for the next ~jiffie before touching IRQs */
+	if (i915_spin_request(req, state, 5))
+		goto complete;
+
+	intel_wait_init(&wait, req->seqno);
+	set_current_state(state);
+	if (intel_engine_add_wait(req->engine, &wait))
+		/* In order to check that we haven't missed the interrupt
+		 * as we enabled it, we need to kick ourselves to do a
+		 * coherent check on the seqno before we sleep.
+		 */
+		goto wakeup;
+
+	add_wait_queue(&req->i915->gpu_error.wait_queue, &reset);
+	for (;;) {
+		if (signal_pending_state(state, current)) {
+			ret = -ERESTARTSYS;
+			break;
+		}
+
+		/* Ensure that even if the GPU hangs, we get woken up. */
+		i915_queue_hangcheck(req->i915);
+
+		timeout_remain = io_schedule_timeout(timeout_remain);
+		if (timeout_remain == 0) {
+			ret = -ETIME;
+			break;
+		}
+
+		if (intel_wait_complete(&wait))
+			break;
+
+wakeup:
+		set_current_state(state);
+
+		/* Carefully check if the request is complete, giving time
+		 * for the seqno to be visible following the interrupt.
+		 * We also have to check in case we are kicked by the GPU
+		 * reset in order to drop the struct_mutex.
+		 */
+		if (__i915_request_irq_complete(req))
+			break;
+
+		/* Only spin if we know the GPU is processing this request */
+		if (i915_spin_request(req, state, 2))
+			break;
+	}
+	remove_wait_queue(&req->i915->gpu_error.wait_queue, &reset);
+
+	intel_engine_remove_wait(req->engine, &wait);
+	__set_current_state(TASK_RUNNING);
+complete:
+	trace_i915_gem_request_wait_end(req);
+
+	if (timeout) {
+		*timeout -= ktime_get_raw_ns();
+		if (*timeout < 0)
+			*timeout = 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 regrssion from the timespec->ktime conversion.
+		 */
+		if (ret == -ETIME && *timeout < jiffies_to_usecs(1)*1000)
+			*timeout = 0;
+	}
+
+	if (rps && req->seqno == req->engine->last_submitted_seqno) {
+		/* The GPU is now idle and this client has stalled.
+		 * Since no other client has submitted a request in the
+		 * meantime, assume that this client is the only one
+		 * supplying work to the GPU but is unable to keep that
+		 * work supplied because it is waiting. Since the GPU is
+		 * then never kept fully busy, RPS autoclocking will
+		 * keep the clocks relatively low, causing further delays.
+		 * Compensate by giving the synchronous client credit for
+		 * a waitboost next time.
+		 */
+		spin_lock(&req->i915->rps.client_lock);
+		list_del_init(&rps->link);
+		spin_unlock(&req->i915->rps.client_lock);
+	}
+
+	return ret;
+}
+
+/**
+ * Waits for a request to be signaled, and cleans up the
+ * request and object lists appropriately for that event.
+ */
+int i915_wait_request(struct drm_i915_gem_request *req)
+{
+	int ret;
+
+	BUG_ON(req == NULL);
+	BUG_ON(!mutex_is_locked(&req->i915->dev->struct_mutex));
+
+	ret = __i915_wait_request(req, req->i915->mm.interruptible,
+				  NULL, NULL);
+	if (ret)
+		return ret;
+
+	/* If the GPU hung, we want to keep the requests to find the guilty. */
+	if (req->reset_counter == i915_reset_counter(&req->i915->gpu_error))
+		i915_gem_request_retire_upto(req);
+
+	return 0;
+}
+
+void i915_gem_request_free(struct kref *req_ref)
+{
+	struct drm_i915_gem_request *req =
+	       	container_of(req_ref, typeof(*req), ref);
+	kmem_cache_free(req->i915->requests, req);
+}
diff --git a/drivers/gpu/drm/i915/i915_gem_request.h b/drivers/gpu/drm/i915/i915_gem_request.h
new file mode 100644
index 000000000000..166e0733d2d8
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_gem_request.h
@@ -0,0 +1,245 @@
+/*
+ * Copyright © 2008-2015 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#ifndef I915_GEM_REQUEST_H
+#define I915_GEM_REQUEST_H
+
+/**
+ * Request queue structure.
+ *
+ * The request queue allows us to note sequence numbers that have been emitted
+ * and may be associated with active buffers to be retired.
+ *
+ * By keeping this list, we can avoid having to do questionable sequence
+ * number comparisons on buffer last_read|write_seqno. It also allows an
+ * emission time to be associated with the request for tracking how far ahead
+ * of the GPU the submission is.
+ *
+ * The requests are reference counted, so upon creation they should have an
+ * initial reference taken using kref_init
+ */
+struct drm_i915_gem_request {
+	struct kref ref;
+
+	/** On Which ring this request was generated */
+	struct drm_i915_private *i915;
+
+	/**
+	 * Context and ring buffer related to this request
+	 * Contexts are refcounted, so when this request is associated with a
+	 * context, we must increment the context's refcount, to guarantee that
+	 * it persists while any request is linked to it. Requests themselves
+	 * are also refcounted, so the request will only be freed when the last
+	 * reference to it is dismissed, and the code in
+	 * i915_gem_request_free() will then decrement the refcount on the
+	 * context.
+	 */
+	struct i915_gem_context *ctx;
+	struct intel_engine_cs *engine;
+	struct intel_ringbuffer *ringbuf;
+	struct intel_signal_node signaling;
+
+	unsigned reset_counter;
+
+	/** GEM sequence number associated with the previous request,
+	 * when the HWS breadcrumb is equal to this the GPU is processing
+	 * this request.
+	 */
+	u32 previous_seqno;
+
+	/** GEM sequence number associated with this request,
+	 * when the HWS breadcrumb is equal or greater than this the GPU
+	 * has finished processing this request.
+	 */
+	u32 seqno;
+
+	/** Position in the ringbuffer of the start of the request */
+	u32 head;
+
+	/**
+	 * Position in the ringbuffer of the start of the postfix.
+	 * This is required to calculate the maximum available ringbuffer
+	 * space without overwriting the postfix.
+	 */
+	u32 postfix;
+
+	/** Position in the ringbuffer of the end of the whole request */
+	u32 tail;
+
+	/** Preallocate space in the ringbuffer for the emitting the request */
+	u32 reserved_space;
+
+
+	/**
+	 * Context related to the previous request.
+	 * As the contexts are accessed by the hardware until the switch is
+	 * completed to a new context, the hardware may still be writing
+	 * to the context object after the breadcrumb is visible. We must
+	 * not unpin/unbind/prune that object whilst still active and so
+	 * we keep the previous context pinned until the following (this)
+	 * request is retired.
+	 */
+	struct i915_gem_context *previous_context;
+
+
+	/** Batch buffer related to this request if any (used for
+	 * error state dump only) */
+	struct drm_i915_gem_object *batch_obj;
+
+	/** Time at which this request was emitted, in jiffies. */
+	unsigned long emitted_jiffies;
+
+	/** global list entry for this request */
+	struct list_head list;
+
+	struct drm_i915_file_private *file_priv;
+	/** file_priv list entry for this request */
+	struct list_head client_list;
+
+	/** process identifier submitting this request */
+	struct pid *pid;
+
+	/**
+	 * The ELSP only accepts two elements at a time, so we queue
+	 * context/tail pairs on a given queue (ring->execlist_queue) until the
+	 * hardware is available. The queue serves a double purpose: we also use
+	 * it to keep track of the up to 2 contexts currently in the hardware
+	 * (usually one in execution and the other queued up by the GPU): We
+	 * only remove elements from the head of the queue when the hardware
+	 * informs us that an element has been completed.
+	 *
+	 * All accesses to the queue are mediated by a spinlock
+	 * (ring->execlist_lock).
+	 */
+
+	/** Execlist link in the submission queue.*/
+	struct list_head execlist_link;
+
+	/** Execlists no. of times this request has been sent to the ELSP */
+	int elsp_submitted;
+
+	/** Execlists context hardware id. */
+	unsigned ctx_hw_id;
+};
+
+static inline struct drm_i915_private *
+__request_to_i915(const struct drm_i915_gem_request *request)
+{
+	return request->i915;
+}
+
+struct drm_i915_gem_request * __must_check
+i915_gem_request_alloc(struct intel_engine_cs *engine,
+		       struct i915_gem_context *ctx);
+void i915_gem_request_free(struct kref *req_ref);
+int i915_gem_request_add_to_client(struct drm_i915_gem_request *req,
+				   struct drm_file *file);
+void i915_gem_request_retire_upto(struct drm_i915_gem_request *req);
+
+static inline uint32_t
+i915_gem_request_get_seqno(struct drm_i915_gem_request *req)
+{
+	return req ? req->seqno : 0;
+}
+
+static inline struct intel_engine_cs *
+i915_gem_request_get_engine(struct drm_i915_gem_request *req)
+{
+	return req ? req->engine : NULL;
+}
+
+static inline struct drm_i915_gem_request *
+i915_gem_request_reference(struct drm_i915_gem_request *req)
+{
+	if (req)
+		kref_get(&req->ref);
+	return req;
+}
+
+static inline void
+i915_gem_request_unreference(struct drm_i915_gem_request *req)
+{
+	kref_put(&req->ref, i915_gem_request_free);
+}
+
+static inline void i915_gem_request_assign(struct drm_i915_gem_request **pdst,
+					   struct drm_i915_gem_request *src)
+{
+	if (src)
+		i915_gem_request_reference(src);
+
+	if (*pdst)
+		i915_gem_request_unreference(*pdst);
+
+	*pdst = src;
+}
+
+void __i915_add_request(struct drm_i915_gem_request *req,
+			struct drm_i915_gem_object *batch_obj,
+			bool flush_caches);
+#define i915_add_request(req) \
+	__i915_add_request(req, NULL, true)
+#define i915_add_request_no_flush(req) \
+	__i915_add_request(req, NULL, false)
+
+struct intel_rps_client;
+
+int __i915_wait_request(struct drm_i915_gem_request *req,
+			bool interruptible,
+			s64 *timeout,
+			struct intel_rps_client *rps);
+int __must_check i915_wait_request(struct drm_i915_gem_request *req);
+
+static inline u32 intel_engine_get_seqno(struct intel_engine_cs *engine);
+
+/**
+ * Returns true if seq1 is later than seq2.
+ */
+static inline bool
+i915_seqno_passed(uint32_t seq1, uint32_t seq2)
+{
+	return (int32_t)(seq1 - seq2) >= 0;
+}
+static inline bool i915_gem_request_started(const struct drm_i915_gem_request *req)
+{
+	return i915_seqno_passed(intel_engine_get_seqno(req->engine),
+				 req->previous_seqno);
+}
+
+static inline bool i915_gem_request_completed(const struct drm_i915_gem_request *req)
+{
+	return i915_seqno_passed(intel_engine_get_seqno(req->engine),
+				 req->seqno);
+}
+
+bool __i915_spin_request(const struct drm_i915_gem_request *request,
+			 int state, unsigned long timeout_us);
+static inline bool i915_spin_request(const struct drm_i915_gem_request *request,
+				     int state, unsigned long timeout_us)
+{
+	return (i915_gem_request_started(request) &&
+		__i915_spin_request(request, state, timeout_us));
+}
+
+#endif /* I915_GEM_REQUEST_H */
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index a066dcfcdd38..3ba5302ce19f 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1400,6 +1400,9 @@ void i915_capture_error_state(struct drm_i915_private *dev_priv,
 	struct drm_i915_error_state *error;
 	unsigned long flags;
 
+	if (READ_ONCE(dev_priv->gpu_error.first_error))
+		return;
+
 	/* Account for pipe specific data like PIPE*STAT */
 	error = kzalloc(sizeof(*error), GFP_ATOMIC);
 	if (!error) {
-- 
2.8.1



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