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diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
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+++ b/drivers/gpu/drm/i915/i915_request.h
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+/*
+ * Copyright © 2008-2018 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_REQUEST_H
+#define I915_REQUEST_H
+
+#include <linux/dma-fence.h>
+
+#include "i915_gem.h"
+#include "i915_scheduler.h"
+#include "i915_sw_fence.h"
+#include "i915_scheduler.h"
+
+#include <uapi/drm/i915_drm.h>
+
+struct drm_file;
+struct drm_i915_gem_object;
+struct i915_request;
+struct i915_timeline;
+
+struct intel_wait {
+ struct rb_node node;
+ struct task_struct *tsk;
+ struct i915_request *request;
+ u32 seqno;
+};
+
+struct intel_signal_node {
+ struct intel_wait wait;
+ struct list_head link;
+};
+
+struct i915_capture_list {
+ struct i915_capture_list *next;
+ struct i915_vma *vma;
+};
+
+/**
+ * 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.
+ *
+ * When modifying this structure be very aware that we perform a lockless
+ * RCU lookup of it that may race against reallocation of the struct
+ * from the slab freelist. We intentionally do not zero the structure on
+ * allocation so that the lookup can use the dangling pointers (and is
+ * cogniscent that those pointers may be wrong). Instead, everything that
+ * needs to be initialised must be done so explicitly.
+ *
+ * The requests are reference counted.
+ */
+struct i915_request {
+ struct dma_fence fence;
+ spinlock_t lock;
+
+ /** 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_request_free() will then decrement the refcount on the
+ * context.
+ */
+ struct i915_gem_context *gem_context;
+ struct intel_engine_cs *engine;
+ struct intel_context *hw_context;
+ struct intel_ring *ring;
+ struct i915_timeline *timeline;
+ struct intel_signal_node signaling;
+
+ /*
+ * Fences for the various phases in the request's lifetime.
+ *
+ * The submit fence is used to await upon all of the request's
+ * dependencies. When it is signaled, the request is ready to run.
+ * It is used by the driver to then queue the request for execution.
+ */
+ struct i915_sw_fence submit;
+ wait_queue_entry_t submitq;
+ wait_queue_head_t execute;
+
+ /*
+ * A list of everyone we wait upon, and everyone who waits upon us.
+ * Even though we will not be submitted to the hardware before the
+ * submit fence is signaled (it waits for all external events as well
+ * as our own requests), the scheduler still needs to know the
+ * dependency tree for the lifetime of the request (from execbuf
+ * to retirement), i.e. bidirectional dependency information for the
+ * request not tied to individual fences.
+ */
+ struct i915_sched_node sched;
+ struct i915_dependency dep;
+
+ /**
+ * GEM sequence number associated with this request on the
+ * global execution timeline. It is zero when the request is not
+ * on the HW queue (i.e. not on the engine timeline list).
+ * Its value is guarded by the timeline spinlock.
+ */
+ u32 global_seqno;
+
+ /** Position in the ring of the start of the request */
+ u32 head;
+
+ /** Position in the ring of the start of the user packets */
+ u32 infix;
+
+ /**
+ * Position in the ring of the start of the postfix.
+ * This is required to calculate the maximum available ring space
+ * without overwriting the postfix.
+ */
+ u32 postfix;
+
+ /** Position in the ring of the end of the whole request */
+ u32 tail;
+
+ /** Position in the ring of the end of any workarounds after the tail */
+ u32 wa_tail;
+
+ /** Preallocate space in the ring for the emitting the request */
+ u32 reserved_space;
+
+ /** Batch buffer related to this request if any (used for
+ * error state dump only).
+ */
+ struct i915_vma *batch;
+ /**
+ * Additional buffers requested by userspace to be captured upon
+ * a GPU hang. The vma/obj on this list are protected by their
+ * active reference - all objects on this list must also be
+ * on the active_list (of their final request).
+ */
+ struct i915_capture_list *capture_list;
+ struct list_head active_list;
+
+ /** Time at which this request was emitted, in jiffies. */
+ unsigned long emitted_jiffies;
+
+ bool waitboost;
+
+ /** engine->request_list entry for this request */
+ struct list_head link;
+
+ /** ring->request_list entry for this request */
+ struct list_head ring_link;
+
+ struct drm_i915_file_private *file_priv;
+ /** file_priv list entry for this request */
+ struct list_head client_link;
+};
+
+#define I915_FENCE_GFP (GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN)
+
+extern const struct dma_fence_ops i915_fence_ops;
+
+static inline bool dma_fence_is_i915(const struct dma_fence *fence)
+{
+ return fence->ops == &i915_fence_ops;
+}
+
+struct i915_request * __must_check
+i915_request_alloc(struct intel_engine_cs *engine,
+ struct i915_gem_context *ctx);
+void i915_request_retire_upto(struct i915_request *rq);
+
+static inline struct i915_request *
+to_request(struct dma_fence *fence)
+{
+ /* We assume that NULL fence/request are interoperable */
+ BUILD_BUG_ON(offsetof(struct i915_request, fence) != 0);
+ GEM_BUG_ON(fence && !dma_fence_is_i915(fence));
+ return container_of(fence, struct i915_request, fence);
+}
+
+static inline struct i915_request *
+i915_request_get(struct i915_request *rq)
+{
+ return to_request(dma_fence_get(&rq->fence));
+}
+
+static inline struct i915_request *
+i915_request_get_rcu(struct i915_request *rq)
+{
+ return to_request(dma_fence_get_rcu(&rq->fence));
+}
+
+static inline void
+i915_request_put(struct i915_request *rq)
+{
+ dma_fence_put(&rq->fence);
+}
+
+/**
+ * i915_request_global_seqno - report the current global seqno
+ * @request - the request
+ *
+ * A request is assigned a global seqno only when it is on the hardware
+ * execution queue. The global seqno can be used to maintain a list of
+ * requests on the same engine in retirement order, for example for
+ * constructing a priority queue for waiting. Prior to its execution, or
+ * if it is subsequently removed in the event of preemption, its global
+ * seqno is zero. As both insertion and removal from the execution queue
+ * may operate in IRQ context, it is not guarded by the usual struct_mutex
+ * BKL. Instead those relying on the global seqno must be prepared for its
+ * value to change between reads. Only when the request is complete can
+ * the global seqno be stable (due to the memory barriers on submitting
+ * the commands to the hardware to write the breadcrumb, if the HWS shows
+ * that it has passed the global seqno and the global seqno is unchanged
+ * after the read, it is indeed complete).
+ */
+static u32
+i915_request_global_seqno(const struct i915_request *request)
+{
+ return READ_ONCE(request->global_seqno);
+}
+
+int i915_request_await_object(struct i915_request *to,
+ struct drm_i915_gem_object *obj,
+ bool write);
+int i915_request_await_dma_fence(struct i915_request *rq,
+ struct dma_fence *fence);
+
+void i915_request_add(struct i915_request *rq);
+
+void __i915_request_submit(struct i915_request *request);
+void i915_request_submit(struct i915_request *request);
+
+void i915_request_skip(struct i915_request *request, int error);
+
+void __i915_request_unsubmit(struct i915_request *request);
+void i915_request_unsubmit(struct i915_request *request);
+
+long i915_request_wait(struct i915_request *rq,
+ unsigned int flags,
+ long timeout)
+ __attribute__((nonnull(1)));
+#define I915_WAIT_INTERRUPTIBLE BIT(0)
+#define I915_WAIT_LOCKED BIT(1) /* struct_mutex held, handle GPU reset */
+#define I915_WAIT_ALL BIT(2) /* used by i915_gem_object_wait() */
+#define I915_WAIT_FOR_IDLE_BOOST BIT(3)
+
+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(u32 seq1, u32 seq2)
+{
+ return (s32)(seq1 - seq2) >= 0;
+}
+
+static inline bool
+__i915_request_completed(const struct i915_request *rq, u32 seqno)
+{
+ GEM_BUG_ON(!seqno);
+ return i915_seqno_passed(intel_engine_get_seqno(rq->engine), seqno) &&
+ seqno == i915_request_global_seqno(rq);
+}
+
+static inline bool i915_request_completed(const struct i915_request *rq)
+{
+ u32 seqno;
+
+ seqno = i915_request_global_seqno(rq);
+ if (!seqno)
+ return false;
+
+ return __i915_request_completed(rq, seqno);
+}
+
+static inline bool i915_request_started(const struct i915_request *rq)
+{
+ u32 seqno;
+
+ seqno = i915_request_global_seqno(rq);
+ if (!seqno)
+ return false;
+
+ return i915_seqno_passed(intel_engine_get_seqno(rq->engine),
+ seqno - 1);
+}
+
+static inline bool i915_sched_node_signaled(const struct i915_sched_node *node)
+{
+ const struct i915_request *rq =
+ container_of(node, const struct i915_request, sched);
+
+ return i915_request_completed(rq);
+}
+
+void i915_retire_requests(struct drm_i915_private *i915);
+
+/*
+ * We treat requests as fences. This is not be to confused with our
+ * "fence registers" but pipeline synchronisation objects ala GL_ARB_sync.
+ * We use the fences to synchronize access from the CPU with activity on the
+ * GPU, for example, we should not rewrite an object's PTE whilst the GPU
+ * is reading them. We also track fences at a higher level to provide
+ * implicit synchronisation around GEM objects, e.g. set-domain will wait
+ * for outstanding GPU rendering before marking the object ready for CPU
+ * access, or a pageflip will wait until the GPU is complete before showing
+ * the frame on the scanout.
+ *
+ * In order to use a fence, the object must track the fence it needs to
+ * serialise with. For example, GEM objects want to track both read and
+ * write access so that we can perform concurrent read operations between
+ * the CPU and GPU engines, as well as waiting for all rendering to
+ * complete, or waiting for the last GPU user of a "fence register". The
+ * object then embeds a #i915_gem_active to track the most recent (in
+ * retirement order) request relevant for the desired mode of access.
+ * The #i915_gem_active is updated with i915_gem_active_set() to track the
+ * most recent fence request, typically this is done as part of
+ * i915_vma_move_to_active().
+ *
+ * When the #i915_gem_active completes (is retired), it will
+ * signal its completion to the owner through a callback as well as mark
+ * itself as idle (i915_gem_active.request == NULL). The owner
+ * can then perform any action, such as delayed freeing of an active
+ * resource including itself.
+ */
+struct i915_gem_active;
+
+typedef void (*i915_gem_retire_fn)(struct i915_gem_active *,
+ struct i915_request *);
+
+struct i915_gem_active {
+ struct i915_request __rcu *request;
+ struct list_head link;
+ i915_gem_retire_fn retire;
+};
+
+void i915_gem_retire_noop(struct i915_gem_active *,
+ struct i915_request *request);
+
+/**
+ * init_request_active - prepares the activity tracker for use
+ * @active - the active tracker
+ * @func - a callback when then the tracker is retired (becomes idle),
+ * can be NULL
+ *
+ * init_request_active() prepares the embedded @active struct for use as
+ * an activity tracker, that is for tracking the last known active request
+ * associated with it. When the last request becomes idle, when it is retired
+ * after completion, the optional callback @func is invoked.
+ */
+static inline void
+init_request_active(struct i915_gem_active *active,
+ i915_gem_retire_fn retire)
+{
+ RCU_INIT_POINTER(active->request, NULL);
+ INIT_LIST_HEAD(&active->link);
+ active->retire = retire ?: i915_gem_retire_noop;
+}
+
+/**
+ * i915_gem_active_set - updates the tracker to watch the current request
+ * @active - the active tracker
+ * @request - the request to watch
+ *
+ * i915_gem_active_set() watches the given @request for completion. Whilst
+ * that @request is busy, the @active reports busy. When that @request is
+ * retired, the @active tracker is updated to report idle.
+ */
+static inline void
+i915_gem_active_set(struct i915_gem_active *active,
+ struct i915_request *request)
+{
+ list_move(&active->link, &request->active_list);
+ rcu_assign_pointer(active->request, request);
+}
+
+/**
+ * i915_gem_active_set_retire_fn - updates the retirement callback
+ * @active - the active tracker
+ * @fn - the routine called when the request is retired
+ * @mutex - struct_mutex used to guard retirements
+ *
+ * i915_gem_active_set_retire_fn() updates the function pointer that
+ * is called when the final request associated with the @active tracker
+ * is retired.
+ */
+static inline void
+i915_gem_active_set_retire_fn(struct i915_gem_active *active,
+ i915_gem_retire_fn fn,
+ struct mutex *mutex)
+{
+ lockdep_assert_held(mutex);
+ active->retire = fn ?: i915_gem_retire_noop;
+}
+
+static inline struct i915_request *
+__i915_gem_active_peek(const struct i915_gem_active *active)
+{
+ /*
+ * Inside the error capture (running with the driver in an unknown
+ * state), we want to bend the rules slightly (a lot).
+ *
+ * Work is in progress to make it safer, in the meantime this keeps
+ * the known issue from spamming the logs.
+ */
+ return rcu_dereference_protected(active->request, 1);
+}
+
+/**
+ * i915_gem_active_raw - return the active request
+ * @active - the active tracker
+ *
+ * i915_gem_active_raw() returns the current request being tracked, or NULL.
+ * It does not obtain a reference on the request for the caller, so the caller
+ * must hold struct_mutex.
+ */
+static inline struct i915_request *
+i915_gem_active_raw(const struct i915_gem_active *active, struct mutex *mutex)
+{
+ return rcu_dereference_protected(active->request,
+ lockdep_is_held(mutex));
+}
+
+/**
+ * i915_gem_active_peek - report the active request being monitored
+ * @active - the active tracker
+ *
+ * i915_gem_active_peek() returns the current request being tracked if
+ * still active, or NULL. It does not obtain a reference on the request
+ * for the caller, so the caller must hold struct_mutex.
+ */
+static inline struct i915_request *
+i915_gem_active_peek(const struct i915_gem_active *active, struct mutex *mutex)
+{
+ struct i915_request *request;
+
+ request = i915_gem_active_raw(active, mutex);
+ if (!request || i915_request_completed(request))
+ return NULL;
+
+ return request;
+}
+
+/**
+ * i915_gem_active_get - return a reference to the active request
+ * @active - the active tracker
+ *
+ * i915_gem_active_get() returns a reference to the active request, or NULL
+ * if the active tracker is idle. The caller must hold struct_mutex.
+ */
+static inline struct i915_request *
+i915_gem_active_get(const struct i915_gem_active *active, struct mutex *mutex)
+{
+ return i915_request_get(i915_gem_active_peek(active, mutex));
+}
+
+/**
+ * __i915_gem_active_get_rcu - return a reference to the active request
+ * @active - the active tracker
+ *
+ * __i915_gem_active_get() returns a reference to the active request, or NULL
+ * if the active tracker is idle. The caller must hold the RCU read lock, but
+ * the returned pointer is safe to use outside of RCU.
+ */
+static inline struct i915_request *
+__i915_gem_active_get_rcu(const struct i915_gem_active *active)
+{
+ /*
+ * Performing a lockless retrieval of the active request is super
+ * tricky. SLAB_TYPESAFE_BY_RCU merely guarantees that the backing
+ * slab of request objects will not be freed whilst we hold the
+ * RCU read lock. It does not guarantee that the request itself
+ * will not be freed and then *reused*. Viz,
+ *
+ * Thread A Thread B
+ *
+ * rq = active.request
+ * retire(rq) -> free(rq);
+ * (rq is now first on the slab freelist)
+ * active.request = NULL
+ *
+ * rq = new submission on a new object
+ * ref(rq)
+ *
+ * To prevent the request from being reused whilst the caller
+ * uses it, we take a reference like normal. Whilst acquiring
+ * the reference we check that it is not in a destroyed state
+ * (refcnt == 0). That prevents the request being reallocated
+ * whilst the caller holds on to it. To check that the request
+ * was not reallocated as we acquired the reference we have to
+ * check that our request remains the active request across
+ * the lookup, in the same manner as a seqlock. The visibility
+ * of the pointer versus the reference counting is controlled
+ * by using RCU barriers (rcu_dereference and rcu_assign_pointer).
+ *
+ * In the middle of all that, we inspect whether the request is
+ * complete. Retiring is lazy so the request may be completed long
+ * before the active tracker is updated. Querying whether the
+ * request is complete is far cheaper (as it involves no locked
+ * instructions setting cachelines to exclusive) than acquiring
+ * the reference, so we do it first. The RCU read lock ensures the
+ * pointer dereference is valid, but does not ensure that the
+ * seqno nor HWS is the right one! However, if the request was
+ * reallocated, that means the active tracker's request was complete.
+ * If the new request is also complete, then both are and we can
+ * just report the active tracker is idle. If the new request is
+ * incomplete, then we acquire a reference on it and check that
+ * it remained the active request.
+ *
+ * It is then imperative that we do not zero the request on
+ * reallocation, so that we can chase the dangling pointers!
+ * See i915_request_alloc().
+ */
+ do {
+ struct i915_request *request;
+
+ request = rcu_dereference(active->request);
+ if (!request || i915_request_completed(request))
+ return NULL;
+
+ /*
+ * An especially silly compiler could decide to recompute the
+ * result of i915_request_completed, more specifically
+ * re-emit the load for request->fence.seqno. A race would catch
+ * a later seqno value, which could flip the result from true to
+ * false. Which means part of the instructions below might not
+ * be executed, while later on instructions are executed. Due to
+ * barriers within the refcounting the inconsistency can't reach
+ * past the call to i915_request_get_rcu, but not executing
+ * that while still executing i915_request_put() creates
+ * havoc enough. Prevent this with a compiler barrier.
+ */
+ barrier();
+
+ request = i915_request_get_rcu(request);
+
+ /*
+ * What stops the following rcu_access_pointer() from occurring
+ * before the above i915_request_get_rcu()? If we were
+ * to read the value before pausing to get the reference to
+ * the request, we may not notice a change in the active
+ * tracker.
+ *
+ * The rcu_access_pointer() is a mere compiler barrier, which
+ * means both the CPU and compiler are free to perform the
+ * memory read without constraint. The compiler only has to
+ * ensure that any operations after the rcu_access_pointer()
+ * occur afterwards in program order. This means the read may
+ * be performed earlier by an out-of-order CPU, or adventurous
+ * compiler.
+ *
+ * The atomic operation at the heart of
+ * i915_request_get_rcu(), see dma_fence_get_rcu(), is
+ * atomic_inc_not_zero() which is only a full memory barrier
+ * when successful. That is, if i915_request_get_rcu()
+ * returns the request (and so with the reference counted
+ * incremented) then the following read for rcu_access_pointer()
+ * must occur after the atomic operation and so confirm
+ * that this request is the one currently being tracked.
+ *
+ * The corresponding write barrier is part of
+ * rcu_assign_pointer().
+ */
+ if (!request || request == rcu_access_pointer(active->request))
+ return rcu_pointer_handoff(request);
+
+ i915_request_put(request);
+ } while (1);
+}
+
+/**
+ * i915_gem_active_get_unlocked - return a reference to the active request
+ * @active - the active tracker
+ *
+ * i915_gem_active_get_unlocked() returns a reference to the active request,
+ * or NULL if the active tracker is idle. The reference is obtained under RCU,
+ * so no locking is required by the caller.
+ *
+ * The reference should be freed with i915_request_put().
+ */
+static inline struct i915_request *
+i915_gem_active_get_unlocked(const struct i915_gem_active *active)
+{
+ struct i915_request *request;
+
+ rcu_read_lock();
+ request = __i915_gem_active_get_rcu(active);
+ rcu_read_unlock();
+
+ return request;
+}
+
+/**
+ * i915_gem_active_isset - report whether the active tracker is assigned
+ * @active - the active tracker
+ *
+ * i915_gem_active_isset() returns true if the active tracker is currently
+ * assigned to a request. Due to the lazy retiring, that request may be idle
+ * and this may report stale information.
+ */
+static inline bool
+i915_gem_active_isset(const struct i915_gem_active *active)
+{
+ return rcu_access_pointer(active->request);
+}
+
+/**
+ * i915_gem_active_wait - waits until the request is completed
+ * @active - the active request on which to wait
+ * @flags - how to wait
+ * @timeout - how long to wait at most
+ * @rps - userspace client to charge for a waitboost
+ *
+ * i915_gem_active_wait() waits until the request is completed before
+ * returning, without requiring any locks to be held. Note that it does not
+ * retire any requests before returning.
+ *
+ * This function relies on RCU in order to acquire the reference to the active
+ * request without holding any locks. See __i915_gem_active_get_rcu() for the
+ * glory details on how that is managed. Once the reference is acquired, we
+ * can then wait upon the request, and afterwards release our reference,
+ * free of any locking.
+ *
+ * This function wraps i915_request_wait(), see it for the full details on
+ * the arguments.
+ *
+ * Returns 0 if successful, or a negative error code.
+ */
+static inline int
+i915_gem_active_wait(const struct i915_gem_active *active, unsigned int flags)
+{
+ struct i915_request *request;
+ long ret = 0;
+
+ request = i915_gem_active_get_unlocked(active);
+ if (request) {
+ ret = i915_request_wait(request, flags, MAX_SCHEDULE_TIMEOUT);
+ i915_request_put(request);
+ }
+
+ return ret < 0 ? ret : 0;
+}
+
+/**
+ * i915_gem_active_retire - waits until the request is retired
+ * @active - the active request on which to wait
+ *
+ * i915_gem_active_retire() waits until the request is completed,
+ * and then ensures that at least the retirement handler for this
+ * @active tracker is called before returning. If the @active
+ * tracker is idle, the function returns immediately.
+ */
+static inline int __must_check
+i915_gem_active_retire(struct i915_gem_active *active,
+ struct mutex *mutex)
+{
+ struct i915_request *request;
+ long ret;
+
+ request = i915_gem_active_raw(active, mutex);
+ if (!request)
+ return 0;
+
+ ret = i915_request_wait(request,
+ I915_WAIT_INTERRUPTIBLE | I915_WAIT_LOCKED,
+ MAX_SCHEDULE_TIMEOUT);
+ if (ret < 0)
+ return ret;
+
+ list_del_init(&active->link);
+ RCU_INIT_POINTER(active->request, NULL);
+
+ active->retire(active, request);
+
+ return 0;
+}
+
+#define for_each_active(mask, idx) \
+ for (; mask ? idx = ffs(mask) - 1, 1 : 0; mask &= ~BIT(idx))
+
+#endif /* I915_REQUEST_H */