OSCL-LXR linux-6.0.1/​drivers/​gpu/​drm/​i915/​i915_scheduler.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * SPDX-License-Identifier: MIT
  *
  * Copyright © 2018 Intel Corporation
  */
 
 #include <linux/mutex.h>
 
 #include "i915_drv.h"
 #include "i915_request.h"
 #include "i915_scheduler.h"
 
 static struct kmem_cache *slab_dependencies;
 static struct kmem_cache *slab_priorities;
 
 static DEFINE_SPINLOCK(schedule_lock);
 
 static const struct i915_request *
 node_to_request(const struct i915_sched_node *node)
 {
     return container_of(node, const struct i915_request, sched);
 }
 
 static inline bool node_started(const struct i915_sched_node *node)
 {
     return i915_request_started(node_to_request(node));
 }
 
 static inline bool node_signaled(const struct i915_sched_node *node)
 {
     return i915_request_completed(node_to_request(node));
 }
 
 static inline struct i915_priolist *to_priolist(struct rb_node *rb)
 {
     return rb_entry(rb, struct i915_priolist, node);
 }
 
 static void assert_priolists(struct i915_sched_engine * const sched_engine)
 {
     struct rb_node *rb;
     long last_prio;
 
     if (!IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
         return;
 
     GEM_BUG_ON(rb_first_cached(&sched_engine->queue) !=
            rb_first(&sched_engine->queue.rb_root));
 
     last_prio = INT_MAX;
     for (rb = rb_first_cached(&sched_engine->queue); rb; rb = rb_next(rb)) {
         const struct i915_priolist *p = to_priolist(rb);
 
         GEM_BUG_ON(p->priority > last_prio);
         last_prio = p->priority;
     }
 }
 
 struct list_head *
 i915_sched_lookup_priolist(struct i915_sched_engine *sched_engine, int prio)
 {
     struct i915_priolist *p;
     struct rb_node **parent, *rb;
     bool first = true;
 
     lockdep_assert_held(&sched_engine->lock);
     assert_priolists(sched_engine);
 
     if (unlikely(sched_engine->no_priolist))
         prio = I915_PRIORITY_NORMAL;
 
 find_priolist:
     /* most positive priority is scheduled first, equal priorities fifo */
     rb = NULL;
     parent = &sched_engine->queue.rb_root.rb_node;
     while (*parent) {
         rb = *parent;
         p = to_priolist(rb);
         if (prio > p->priority) {
             parent = &rb->rb_left;
         } else if (prio < p->priority) {
             parent = &rb->rb_right;
             first = false;
         } else {
             return &p->requests;
         }
     }
 
     if (prio == I915_PRIORITY_NORMAL) {
         p = &sched_engine->default_priolist;
     } else {
         p = kmem_cache_alloc(slab_priorities, GFP_ATOMIC);
         /* Convert an allocation failure to a priority bump */
         if (unlikely(!p)) {
             prio = I915_PRIORITY_NORMAL; /* recurses just once */
 
             /* To maintain ordering with all rendering, after an
              * allocation failure we have to disable all scheduling.
              * Requests will then be executed in fifo, and schedule
              * will ensure that dependencies are emitted in fifo.
              * There will be still some reordering with existing
              * requests, so if userspace lied about their
              * dependencies that reordering may be visible.
              */
             sched_engine->no_priolist = true;
             goto find_priolist;
         }
     }
 
     p->priority = prio;
     INIT_LIST_HEAD(&p->requests);
 
     rb_link_node(&p->node, rb, parent);
     rb_insert_color_cached(&p->node, &sched_engine->queue, first);
 
     return &p->requests;
 }
 
 void __i915_priolist_free(struct i915_priolist *p)
 {
     kmem_cache_free(slab_priorities, p);
 }
 
 struct sched_cache {
     struct list_head *priolist;
 };
 
 static struct i915_sched_engine *
 lock_sched_engine(struct i915_sched_node *node,
           struct i915_sched_engine *locked,
           struct sched_cache *cache)
 {
     const struct i915_request *rq = node_to_request(node);
     struct i915_sched_engine *sched_engine;
 
     GEM_BUG_ON(!locked);
 
     /*
      * Virtual engines complicate acquiring the engine timeline lock,
      * as their rq->engine pointer is not stable until under that
      * engine lock. The simple ploy we use is to take the lock then
      * check that the rq still belongs to the newly locked engine.
      */
     while (locked != (sched_engine = READ_ONCE(rq->engine)->sched_engine)) {
         spin_unlock(&locked->lock);
         memset(cache, 0, sizeof(*cache));
         spin_lock(&sched_engine->lock);
         locked = sched_engine;
     }
 
     GEM_BUG_ON(locked != sched_engine);
     return locked;
 }
 
 static void __i915_schedule(struct i915_sched_node *node,
                 const struct i915_sched_attr *attr)
 {
     const int prio = max(attr->priority, node->attr.priority);
     struct i915_sched_engine *sched_engine;
     struct i915_dependency *dep, *p;
     struct i915_dependency stack;
     struct sched_cache cache;
     LIST_HEAD(dfs);
 
     /* Needed in order to use the temporary link inside i915_dependency */
     lockdep_assert_held(&schedule_lock);
     GEM_BUG_ON(prio == I915_PRIORITY_INVALID);
 
     if (node_signaled(node))
         return;
 
     stack.signaler = node;
     list_add(&stack.dfs_link, &dfs);
 
     /*
      * Recursively bump all dependent priorities to match the new request.
      *
      * A naive approach would be to use recursion:
      * static void update_priorities(struct i915_sched_node *node, prio) {
      *  list_for_each_entry(dep, &node->signalers_list, signal_link)
      *      update_priorities(dep->signal, prio)
      *  queue_request(node);
      * }
      * but that may have unlimited recursion depth and so runs a very
      * real risk of overunning the kernel stack. Instead, we build
      * a flat list of all dependencies starting with the current request.
      * As we walk the list of dependencies, we add all of its dependencies
      * to the end of the list (this may include an already visited
      * request) and continue to walk onwards onto the new dependencies. The
      * end result is a topological list of requests in reverse order, the
      * last element in the list is the request we must execute first.
      */
     list_for_each_entry(dep, &dfs, dfs_link) {
         struct i915_sched_node *node = dep->signaler;
 
         /* If we are already flying, we know we have no signalers */
         if (node_started(node))
             continue;
 
         /*
          * Within an engine, there can be no cycle, but we may
          * refer to the same dependency chain multiple times
          * (redundant dependencies are not eliminated) and across
          * engines.
          */
         list_for_each_entry(p, &node->signalers_list, signal_link) {
             GEM_BUG_ON(p == dep); /* no cycles! */
 
             if (node_signaled(p->signaler))
                 continue;
 
             if (prio > READ_ONCE(p->signaler->attr.priority))
                 list_move_tail(&p->dfs_link, &dfs);
         }
     }
 
     /*
      * If we didn't need to bump any existing priorities, and we haven't
      * yet submitted this request (i.e. there is no potential race with
      * execlists_submit_request()), we can set our own priority and skip
      * acquiring the engine locks.
      */
     if (node->attr.priority == I915_PRIORITY_INVALID) {
         GEM_BUG_ON(!list_empty(&node->link));
         node->attr = *attr;
 
         if (stack.dfs_link.next == stack.dfs_link.prev)
             return;
 
         __list_del_entry(&stack.dfs_link);
     }
 
     memset(&cache, 0, sizeof(cache));
     sched_engine = node_to_request(node)->engine->sched_engine;
     spin_lock(&sched_engine->lock);
 
     /* Fifo and depth-first replacement ensure our deps execute before us */
     sched_engine = lock_sched_engine(node, sched_engine, &cache);
     list_for_each_entry_safe_reverse(dep, p, &dfs, dfs_link) {
         struct i915_request *from = container_of(dep->signaler,
                              struct i915_request,
                              sched);
         INIT_LIST_HEAD(&dep->dfs_link);
 
         node = dep->signaler;
         sched_engine = lock_sched_engine(node, sched_engine, &cache);
         lockdep_assert_held(&sched_engine->lock);
 
         /* Recheck after acquiring the engine->timeline.lock */
         if (prio <= node->attr.priority || node_signaled(node))
             continue;
 
         GEM_BUG_ON(node_to_request(node)->engine->sched_engine !=
                sched_engine);
 
         /* Must be called before changing the nodes priority */
         if (sched_engine->bump_inflight_request_prio)
             sched_engine->bump_inflight_request_prio(from, prio);
 
         WRITE_ONCE(node->attr.priority, prio);
 
         /*
          * Once the request is ready, it will be placed into the
          * priority lists and then onto the HW runlist. Before the
          * request is ready, it does not contribute to our preemption
          * decisions and we can safely ignore it, as it will, and
          * any preemption required, be dealt with upon submission.
          * See engine->submit_request()
          */
         if (list_empty(&node->link))
             continue;
 
         if (i915_request_in_priority_queue(node_to_request(node))) {
             if (!cache.priolist)
                 cache.priolist =
                     i915_sched_lookup_priolist(sched_engine,
                                    prio);
             list_move_tail(&node->link, cache.priolist);
         }
 
         /* Defer (tasklet) submission until after all of our updates. */
         if (sched_engine->kick_backend)
             sched_engine->kick_backend(node_to_request(node), prio);
     }
 
     spin_unlock(&sched_engine->lock);
 }
 
 void i915_schedule(struct i915_request *rq, const struct i915_sched_attr *attr)
 {
     spin_lock_irq(&schedule_lock);
     __i915_schedule(&rq->sched, attr);
     spin_unlock_irq(&schedule_lock);
 }
 
 void i915_sched_node_init(struct i915_sched_node *node)
 {
     INIT_LIST_HEAD(&node->signalers_list);
     INIT_LIST_HEAD(&node->waiters_list);
     INIT_LIST_HEAD(&node->link);
 
     i915_sched_node_reinit(node);
 }
 
 void i915_sched_node_reinit(struct i915_sched_node *node)
 {
     node->attr.priority = I915_PRIORITY_INVALID;
     node->semaphores = 0;
     node->flags = 0;
 
     GEM_BUG_ON(!list_empty(&node->signalers_list));
     GEM_BUG_ON(!list_empty(&node->waiters_list));
     GEM_BUG_ON(!list_empty(&node->link));
 }
 
 static struct i915_dependency *
 i915_dependency_alloc(void)
 {
     return kmem_cache_alloc(slab_dependencies, GFP_KERNEL);
 }
 
 static void
 i915_dependency_free(struct i915_dependency *dep)
 {
     kmem_cache_free(slab_dependencies, dep);
 }
 
 bool __i915_sched_node_add_dependency(struct i915_sched_node *node,
                       struct i915_sched_node *signal,
                       struct i915_dependency *dep,
                       unsigned long flags)
 {
     bool ret = false;
 
     spin_lock_irq(&schedule_lock);
 
     if (!node_signaled(signal)) {
         INIT_LIST_HEAD(&dep->dfs_link);
         dep->signaler = signal;
         dep->waiter = node;
         dep->flags = flags;
 
         /* All set, now publish. Beware the lockless walkers. */
         list_add_rcu(&dep->signal_link, &node->signalers_list);
         list_add_rcu(&dep->wait_link, &signal->waiters_list);
 
         /* Propagate the chains */
         node->flags |= signal->flags;
         ret = true;
     }
 
     spin_unlock_irq(&schedule_lock);
 
     return ret;
 }
 
 int i915_sched_node_add_dependency(struct i915_sched_node *node,
                    struct i915_sched_node *signal,
                    unsigned long flags)
 {
     struct i915_dependency *dep;
 
     dep = i915_dependency_alloc();
     if (!dep)
         return -ENOMEM;
 
     if (!__i915_sched_node_add_dependency(node, signal, dep,
                           flags | I915_DEPENDENCY_ALLOC))
         i915_dependency_free(dep);
 
     return 0;
 }
 
 void i915_sched_node_fini(struct i915_sched_node *node)
 {
     struct i915_dependency *dep, *tmp;
 
     spin_lock_irq(&schedule_lock);
 
     /*
      * Everyone we depended upon (the fences we wait to be signaled)
      * should retire before us and remove themselves from our list.
      * However, retirement is run independently on each timeline and
      * so we may be called out-of-order.
      */
     list_for_each_entry_safe(dep, tmp, &node->signalers_list, signal_link) {
         GEM_BUG_ON(!list_empty(&dep->dfs_link));
 
         list_del_rcu(&dep->wait_link);
         if (dep->flags & I915_DEPENDENCY_ALLOC)
             i915_dependency_free(dep);
     }
     INIT_LIST_HEAD(&node->signalers_list);
 
     /* Remove ourselves from everyone who depends upon us */
     list_for_each_entry_safe(dep, tmp, &node->waiters_list, wait_link) {
         GEM_BUG_ON(dep->signaler != node);
         GEM_BUG_ON(!list_empty(&dep->dfs_link));
 
         list_del_rcu(&dep->signal_link);
         if (dep->flags & I915_DEPENDENCY_ALLOC)
             i915_dependency_free(dep);
     }
     INIT_LIST_HEAD(&node->waiters_list);
 
     spin_unlock_irq(&schedule_lock);
 }
 
 void i915_request_show_with_schedule(struct drm_printer *m,
                      const struct i915_request *rq,
                      const char *prefix,
                      int indent)
 {
     struct i915_dependency *dep;
 
     i915_request_show(m, rq, prefix, indent);
     if (i915_request_completed(rq))
         return;
 
     rcu_read_lock();
     for_each_signaler(dep, rq) {
         const struct i915_request *signaler =
             node_to_request(dep->signaler);
 
         /* Dependencies along the same timeline are expected. */
         if (signaler->timeline == rq->timeline)
             continue;
 
         if (__i915_request_is_complete(signaler))
             continue;
 
         i915_request_show(m, signaler, prefix, indent + 2);
     }
     rcu_read_unlock();
 }
 
 static void default_destroy(struct kref *kref)
 {
     struct i915_sched_engine *sched_engine =
         container_of(kref, typeof(*sched_engine), ref);
 
     tasklet_kill(&sched_engine->tasklet); /* flush the callback */
     kfree(sched_engine);
 }
 
 static bool default_disabled(struct i915_sched_engine *sched_engine)
 {
     return false;
 }
 
 struct i915_sched_engine *
 i915_sched_engine_create(unsigned int subclass)
 {
     struct i915_sched_engine *sched_engine;
 
     sched_engine = kzalloc(sizeof(*sched_engine), GFP_KERNEL);
     if (!sched_engine)
         return NULL;
 
     kref_init(&sched_engine->ref);
 
     sched_engine->queue = RB_ROOT_CACHED;
     sched_engine->queue_priority_hint = INT_MIN;
     sched_engine->destroy = default_destroy;
     sched_engine->disabled = default_disabled;
 
     INIT_LIST_HEAD(&sched_engine->requests);
     INIT_LIST_HEAD(&sched_engine->hold);
 
     spin_lock_init(&sched_engine->lock);
     lockdep_set_subclass(&sched_engine->lock, subclass);
 
     /*
      * Due to an interesting quirk in lockdep's internal debug tracking,
      * after setting a subclass we must ensure the lock is used. Otherwise,
      * nr_unused_locks is incremented once too often.
      */
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
     local_irq_disable();
     lock_map_acquire(&sched_engine->lock.dep_map);
     lock_map_release(&sched_engine->lock.dep_map);
     local_irq_enable();
 #endif
 
     return sched_engine;
 }
 
 void i915_scheduler_module_exit(void)
 {
     kmem_cache_destroy(slab_dependencies);
     kmem_cache_destroy(slab_priorities);
 }
 
 int __init i915_scheduler_module_init(void)
 {
     slab_dependencies = KMEM_CACHE(i915_dependency,
                           SLAB_HWCACHE_ALIGN |
                           SLAB_TYPESAFE_BY_RCU);
     if (!slab_dependencies)
         return -ENOMEM;
 
     slab_priorities = KMEM_CACHE(i915_priolist, 0);
     if (!slab_priorities)
         goto err_priorities;
 
     return 0;
 
 err_priorities:
     kmem_cache_destroy(slab_priorities);
     return -ENOMEM;
 }

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