diff options
Diffstat (limited to 'drivers/gpu/drm/i915/intel_breadcrumbs.c')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_breadcrumbs.c | 892 |
1 files changed, 0 insertions, 892 deletions
diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c deleted file mode 100644 index 447c5256f63a..000000000000 --- a/drivers/gpu/drm/i915/intel_breadcrumbs.c +++ /dev/null @@ -1,892 +0,0 @@ -/* - * Copyright © 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 <linux/kthread.h> -#include <uapi/linux/sched/types.h> - -#include "i915_drv.h" - -#define task_asleep(tsk) ((tsk)->state & TASK_NORMAL && !(tsk)->on_rq) - -static unsigned int __intel_breadcrumbs_wakeup(struct intel_breadcrumbs *b) -{ - struct intel_wait *wait; - unsigned int result = 0; - - lockdep_assert_held(&b->irq_lock); - - wait = b->irq_wait; - if (wait) { - /* - * N.B. Since task_asleep() and ttwu are not atomic, the - * waiter may actually go to sleep after the check, causing - * us to suppress a valid wakeup. We prefer to reduce the - * number of false positive missed_breadcrumb() warnings - * at the expense of a few false negatives, as it it easy - * to trigger a false positive under heavy load. Enough - * signal should remain from genuine missed_breadcrumb() - * for us to detect in CI. - */ - bool was_asleep = task_asleep(wait->tsk); - - result = ENGINE_WAKEUP_WAITER; - if (wake_up_process(wait->tsk) && was_asleep) - result |= ENGINE_WAKEUP_ASLEEP; - } - - return result; -} - -unsigned int intel_engine_wakeup(struct intel_engine_cs *engine) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - unsigned long flags; - unsigned int result; - - spin_lock_irqsave(&b->irq_lock, flags); - result = __intel_breadcrumbs_wakeup(b); - spin_unlock_irqrestore(&b->irq_lock, flags); - - return result; -} - -static unsigned long wait_timeout(void) -{ - return round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES); -} - -static noinline void missed_breadcrumb(struct intel_engine_cs *engine) -{ - if (GEM_SHOW_DEBUG()) { - struct drm_printer p = drm_debug_printer(__func__); - - intel_engine_dump(engine, &p, - "%s missed breadcrumb at %pS\n", - engine->name, __builtin_return_address(0)); - } - - set_bit(engine->id, &engine->i915->gpu_error.missed_irq_rings); -} - -static void intel_breadcrumbs_hangcheck(struct timer_list *t) -{ - struct intel_engine_cs *engine = - from_timer(engine, t, breadcrumbs.hangcheck); - struct intel_breadcrumbs *b = &engine->breadcrumbs; - unsigned int irq_count; - - if (!b->irq_armed) - return; - - irq_count = READ_ONCE(b->irq_count); - if (b->hangcheck_interrupts != irq_count) { - b->hangcheck_interrupts = irq_count; - mod_timer(&b->hangcheck, wait_timeout()); - return; - } - - /* We keep the hangcheck timer alive until we disarm the irq, even - * if there are no waiters at present. - * - * If the waiter was currently running, assume it hasn't had a chance - * to process the pending interrupt (e.g, low priority task on a loaded - * system) and wait until it sleeps before declaring a missed interrupt. - * - * If the waiter was asleep (and not even pending a wakeup), then we - * must have missed an interrupt as the GPU has stopped advancing - * but we still have a waiter. Assuming all batches complete within - * DRM_I915_HANGCHECK_JIFFIES [1.5s]! - */ - if (intel_engine_wakeup(engine) & ENGINE_WAKEUP_ASLEEP) { - missed_breadcrumb(engine); - mod_timer(&b->fake_irq, jiffies + 1); - } else { - mod_timer(&b->hangcheck, wait_timeout()); - } -} - -static void intel_breadcrumbs_fake_irq(struct timer_list *t) -{ - struct intel_engine_cs *engine = - from_timer(engine, t, breadcrumbs.fake_irq); - struct intel_breadcrumbs *b = &engine->breadcrumbs; - - /* - * The timer persists in case we cannot enable interrupts, - * or if we have previously seen seqno/interrupt incoherency - * ("missed interrupt" syndrome, better known as a "missed breadcrumb"). - * Here the worker will wake up every jiffie in order to kick the - * oldest waiter to do the coherent seqno check. - */ - - spin_lock_irq(&b->irq_lock); - if (b->irq_armed && !__intel_breadcrumbs_wakeup(b)) - __intel_engine_disarm_breadcrumbs(engine); - spin_unlock_irq(&b->irq_lock); - if (!b->irq_armed) - return; - - /* If the user has disabled the fake-irq, restore the hangchecking */ - if (!test_bit(engine->id, &engine->i915->gpu_error.missed_irq_rings)) { - mod_timer(&b->hangcheck, wait_timeout()); - return; - } - - mod_timer(&b->fake_irq, jiffies + 1); -} - -static void irq_enable(struct intel_engine_cs *engine) -{ - /* - * FIXME: Ideally we want this on the API boundary, but for the - * sake of testing with mock breadcrumbs (no HW so unable to - * enable irqs) we place it deep within the bowels, at the point - * of no return. - */ - GEM_BUG_ON(!intel_irqs_enabled(engine->i915)); - - /* Enabling the IRQ may miss the generation of the interrupt, but - * we still need to force the barrier before reading the seqno, - * just in case. - */ - set_bit(ENGINE_IRQ_BREADCRUMB, &engine->irq_posted); - - /* Caller disables interrupts */ - if (engine->irq_enable) { - spin_lock(&engine->i915->irq_lock); - engine->irq_enable(engine); - spin_unlock(&engine->i915->irq_lock); - } -} - -static void irq_disable(struct intel_engine_cs *engine) -{ - /* Caller disables interrupts */ - if (engine->irq_disable) { - spin_lock(&engine->i915->irq_lock); - engine->irq_disable(engine); - spin_unlock(&engine->i915->irq_lock); - } -} - -void __intel_engine_disarm_breadcrumbs(struct intel_engine_cs *engine) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - - lockdep_assert_held(&b->irq_lock); - GEM_BUG_ON(b->irq_wait); - GEM_BUG_ON(!b->irq_armed); - - GEM_BUG_ON(!b->irq_enabled); - if (!--b->irq_enabled) - irq_disable(engine); - - b->irq_armed = false; -} - -void intel_engine_pin_breadcrumbs_irq(struct intel_engine_cs *engine) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - - spin_lock_irq(&b->irq_lock); - if (!b->irq_enabled++) - irq_enable(engine); - GEM_BUG_ON(!b->irq_enabled); /* no overflow! */ - spin_unlock_irq(&b->irq_lock); -} - -void intel_engine_unpin_breadcrumbs_irq(struct intel_engine_cs *engine) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - - spin_lock_irq(&b->irq_lock); - GEM_BUG_ON(!b->irq_enabled); /* no underflow! */ - if (!--b->irq_enabled) - irq_disable(engine); - spin_unlock_irq(&b->irq_lock); -} - -void intel_engine_disarm_breadcrumbs(struct intel_engine_cs *engine) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - struct intel_wait *wait, *n; - - if (!b->irq_armed) - return; - - /* - * We only disarm the irq when we are idle (all requests completed), - * so if the bottom-half remains asleep, it missed the request - * completion. - */ - if (intel_engine_wakeup(engine) & ENGINE_WAKEUP_ASLEEP) - missed_breadcrumb(engine); - - spin_lock_irq(&b->rb_lock); - - spin_lock(&b->irq_lock); - b->irq_wait = NULL; - if (b->irq_armed) - __intel_engine_disarm_breadcrumbs(engine); - spin_unlock(&b->irq_lock); - - rbtree_postorder_for_each_entry_safe(wait, n, &b->waiters, node) { - GEM_BUG_ON(!intel_engine_signaled(engine, wait->seqno)); - RB_CLEAR_NODE(&wait->node); - wake_up_process(wait->tsk); - } - b->waiters = RB_ROOT; - - spin_unlock_irq(&b->rb_lock); -} - -static bool use_fake_irq(const struct intel_breadcrumbs *b) -{ - const struct intel_engine_cs *engine = - container_of(b, struct intel_engine_cs, breadcrumbs); - - if (!test_bit(engine->id, &engine->i915->gpu_error.missed_irq_rings)) - return false; - - /* - * Only start with the heavy weight fake irq timer if we have not - * seen any interrupts since enabling it the first time. If the - * interrupts are still arriving, it means we made a mistake in our - * engine->seqno_barrier(), a timing error that should be transient - * and unlikely to reoccur. - */ - return READ_ONCE(b->irq_count) == b->hangcheck_interrupts; -} - -static void enable_fake_irq(struct intel_breadcrumbs *b) -{ - /* Ensure we never sleep indefinitely */ - if (!b->irq_enabled || use_fake_irq(b)) - mod_timer(&b->fake_irq, jiffies + 1); - else - mod_timer(&b->hangcheck, wait_timeout()); -} - -static bool __intel_breadcrumbs_enable_irq(struct intel_breadcrumbs *b) -{ - struct intel_engine_cs *engine = - container_of(b, struct intel_engine_cs, breadcrumbs); - struct drm_i915_private *i915 = engine->i915; - bool enabled; - - lockdep_assert_held(&b->irq_lock); - if (b->irq_armed) - return false; - - /* The breadcrumb irq will be disarmed on the interrupt after the - * waiters are signaled. This gives us a single interrupt window in - * which we can add a new waiter and avoid the cost of re-enabling - * the irq. - */ - b->irq_armed = true; - - if (I915_SELFTEST_ONLY(b->mock)) { - /* For our mock objects we want to avoid interaction - * with the real hardware (which is not set up). So - * we simply pretend we have enabled the powerwell - * and the irq, and leave it up to the mock - * implementation to call intel_engine_wakeup() - * itself when it wants to simulate a user interrupt, - */ - return true; - } - - /* Since we are waiting on a request, the GPU should be busy - * and should have its own rpm reference. This is tracked - * by i915->gt.awake, we can forgo holding our own wakref - * for the interrupt as before i915->gt.awake is released (when - * the driver is idle) we disarm the breadcrumbs. - */ - - /* No interrupts? Kick the waiter every jiffie! */ - enabled = false; - if (!b->irq_enabled++ && - !test_bit(engine->id, &i915->gpu_error.test_irq_rings)) { - irq_enable(engine); - enabled = true; - } - - enable_fake_irq(b); - return enabled; -} - -static inline struct intel_wait *to_wait(struct rb_node *node) -{ - return rb_entry(node, struct intel_wait, node); -} - -static inline void __intel_breadcrumbs_finish(struct intel_breadcrumbs *b, - struct intel_wait *wait) -{ - lockdep_assert_held(&b->rb_lock); - GEM_BUG_ON(b->irq_wait == wait); - - /* - * This request is completed, so remove it from the tree, mark it as - * complete, and *then* wake up the associated task. N.B. when the - * task wakes up, it will find the empty rb_node, discern that it - * has already been removed from the tree and skip the serialisation - * of the b->rb_lock and b->irq_lock. This means that the destruction - * of the intel_wait is not serialised with the interrupt handler - * by the waiter - it must instead be serialised by the caller. - */ - rb_erase(&wait->node, &b->waiters); - RB_CLEAR_NODE(&wait->node); - - if (wait->tsk->state != TASK_RUNNING) - wake_up_process(wait->tsk); /* implicit smp_wmb() */ -} - -static inline void __intel_breadcrumbs_next(struct intel_engine_cs *engine, - struct rb_node *next) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - - spin_lock(&b->irq_lock); - GEM_BUG_ON(!b->irq_armed); - GEM_BUG_ON(!b->irq_wait); - b->irq_wait = to_wait(next); - spin_unlock(&b->irq_lock); - - /* We always wake up the next waiter that takes over as the bottom-half - * as we may delegate not only the irq-seqno barrier to the next waiter - * but also the task of waking up concurrent waiters. - */ - if (next) - wake_up_process(to_wait(next)->tsk); -} - -static bool __intel_engine_add_wait(struct intel_engine_cs *engine, - struct intel_wait *wait) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - struct rb_node **p, *parent, *completed; - bool first, armed; - u32 seqno; - - GEM_BUG_ON(!wait->seqno); - - /* Insert the request into the retirement ordered list - * of waiters by walking the rbtree. If we are the oldest - * seqno in the tree (the first to be retired), then - * set ourselves as the bottom-half. - * - * As we descend the tree, prune completed branches since we hold the - * spinlock we know that the first_waiter must be delayed and can - * reduce some of the sequential wake up latency if we take action - * ourselves and wake up the completed tasks in parallel. Also, by - * removing stale elements in the tree, we may be able to reduce the - * ping-pong between the old bottom-half and ourselves as first-waiter. - */ - armed = false; - first = true; - parent = NULL; - completed = NULL; - seqno = intel_engine_get_seqno(engine); - - /* If the request completed before we managed to grab the spinlock, - * return now before adding ourselves to the rbtree. We let the - * current bottom-half handle any pending wakeups and instead - * try and get out of the way quickly. - */ - if (i915_seqno_passed(seqno, wait->seqno)) { - RB_CLEAR_NODE(&wait->node); - return first; - } - - p = &b->waiters.rb_node; - while (*p) { - parent = *p; - if (wait->seqno == to_wait(parent)->seqno) { - /* We have multiple waiters on the same seqno, select - * the highest priority task (that with the smallest - * task->prio) to serve as the bottom-half for this - * group. - */ - if (wait->tsk->prio > to_wait(parent)->tsk->prio) { - p = &parent->rb_right; - first = false; - } else { - p = &parent->rb_left; - } - } else if (i915_seqno_passed(wait->seqno, - to_wait(parent)->seqno)) { - p = &parent->rb_right; - if (i915_seqno_passed(seqno, to_wait(parent)->seqno)) - completed = parent; - else - first = false; - } else { - p = &parent->rb_left; - } - } - rb_link_node(&wait->node, parent, p); - rb_insert_color(&wait->node, &b->waiters); - - if (first) { - spin_lock(&b->irq_lock); - b->irq_wait = wait; - /* After assigning ourselves as the new bottom-half, we must - * perform a cursory check to prevent a missed interrupt. - * Either we miss the interrupt whilst programming the hardware, - * or if there was a previous waiter (for a later seqno) they - * may be woken instead of us (due to the inherent race - * in the unlocked read of b->irq_seqno_bh in the irq handler) - * and so we miss the wake up. - */ - armed = __intel_breadcrumbs_enable_irq(b); - spin_unlock(&b->irq_lock); - } - - if (completed) { - /* Advance the bottom-half (b->irq_wait) before we wake up - * the waiters who may scribble over their intel_wait - * just as the interrupt handler is dereferencing it via - * b->irq_wait. - */ - if (!first) { - struct rb_node *next = rb_next(completed); - GEM_BUG_ON(next == &wait->node); - __intel_breadcrumbs_next(engine, next); - } - - do { - struct intel_wait *crumb = to_wait(completed); - completed = rb_prev(completed); - __intel_breadcrumbs_finish(b, crumb); - } while (completed); - } - - GEM_BUG_ON(!b->irq_wait); - GEM_BUG_ON(!b->irq_armed); - GEM_BUG_ON(rb_first(&b->waiters) != &b->irq_wait->node); - - return armed; -} - -bool intel_engine_add_wait(struct intel_engine_cs *engine, - struct intel_wait *wait) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - bool armed; - - spin_lock_irq(&b->rb_lock); - armed = __intel_engine_add_wait(engine, wait); - spin_unlock_irq(&b->rb_lock); - if (armed) - return armed; - - /* Make the caller recheck if its request has already started. */ - return intel_engine_has_started(engine, wait->seqno); -} - -static inline bool chain_wakeup(struct rb_node *rb, int priority) -{ - return rb && to_wait(rb)->tsk->prio <= priority; -} - -static inline int wakeup_priority(struct intel_breadcrumbs *b, - struct task_struct *tsk) -{ - if (tsk == b->signaler) - return INT_MIN; - else - return tsk->prio; -} - -static void __intel_engine_remove_wait(struct intel_engine_cs *engine, - struct intel_wait *wait) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - - lockdep_assert_held(&b->rb_lock); - - if (RB_EMPTY_NODE(&wait->node)) - goto out; - - if (b->irq_wait == wait) { - const int priority = wakeup_priority(b, wait->tsk); - struct rb_node *next; - - /* We are the current bottom-half. Find the next candidate, - * the first waiter in the queue on the remaining oldest - * request. As multiple seqnos may complete in the time it - * takes us to wake up and find the next waiter, we have to - * wake up that waiter for it to perform its own coherent - * completion check. - */ - next = rb_next(&wait->node); - if (chain_wakeup(next, priority)) { - /* If the next waiter is already complete, - * wake it up and continue onto the next waiter. So - * if have a small herd, they will wake up in parallel - * rather than sequentially, which should reduce - * the overall latency in waking all the completed - * clients. - * - * However, waking up a chain adds extra latency to - * the first_waiter. This is undesirable if that - * waiter is a high priority task. - */ - u32 seqno = intel_engine_get_seqno(engine); - - while (i915_seqno_passed(seqno, to_wait(next)->seqno)) { - struct rb_node *n = rb_next(next); - - __intel_breadcrumbs_finish(b, to_wait(next)); - next = n; - if (!chain_wakeup(next, priority)) - break; - } - } - - __intel_breadcrumbs_next(engine, next); - } else { - GEM_BUG_ON(rb_first(&b->waiters) == &wait->node); - } - - GEM_BUG_ON(RB_EMPTY_NODE(&wait->node)); - rb_erase(&wait->node, &b->waiters); - RB_CLEAR_NODE(&wait->node); - -out: - GEM_BUG_ON(b->irq_wait == wait); - GEM_BUG_ON(rb_first(&b->waiters) != - (b->irq_wait ? &b->irq_wait->node : NULL)); -} - -void intel_engine_remove_wait(struct intel_engine_cs *engine, - struct intel_wait *wait) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - - /* Quick check to see if this waiter was already decoupled from - * the tree by the bottom-half to avoid contention on the spinlock - * by the herd. - */ - if (RB_EMPTY_NODE(&wait->node)) { - GEM_BUG_ON(READ_ONCE(b->irq_wait) == wait); - return; - } - - spin_lock_irq(&b->rb_lock); - __intel_engine_remove_wait(engine, wait); - spin_unlock_irq(&b->rb_lock); -} - -static void signaler_set_rtpriority(void) -{ - struct sched_param param = { .sched_priority = 1 }; - - sched_setscheduler_nocheck(current, SCHED_FIFO, ¶m); -} - -static int intel_breadcrumbs_signaler(void *arg) -{ - struct intel_engine_cs *engine = arg; - struct intel_breadcrumbs *b = &engine->breadcrumbs; - struct i915_request *rq, *n; - - /* Install ourselves with high priority to reduce signalling latency */ - signaler_set_rtpriority(); - - do { - bool do_schedule = true; - LIST_HEAD(list); - u32 seqno; - - set_current_state(TASK_INTERRUPTIBLE); - if (list_empty(&b->signals)) - goto sleep; - - /* - * We are either woken up by the interrupt bottom-half, - * or by a client adding a new signaller. In both cases, - * the GPU seqno may have advanced beyond our oldest signal. - * If it has, propagate the signal, remove the waiter and - * check again with the next oldest signal. Otherwise we - * need to wait for a new interrupt from the GPU or for - * a new client. - */ - seqno = intel_engine_get_seqno(engine); - - spin_lock_irq(&b->rb_lock); - list_for_each_entry_safe(rq, n, &b->signals, signaling.link) { - u32 this = rq->signaling.wait.seqno; - - GEM_BUG_ON(!rq->signaling.wait.seqno); - - if (!i915_seqno_passed(seqno, this)) - break; - - if (likely(this == i915_request_global_seqno(rq))) { - __intel_engine_remove_wait(engine, - &rq->signaling.wait); - - rq->signaling.wait.seqno = 0; - __list_del_entry(&rq->signaling.link); - - if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, - &rq->fence.flags)) { - list_add_tail(&rq->signaling.link, - &list); - i915_request_get(rq); - } - } - } - spin_unlock_irq(&b->rb_lock); - - if (!list_empty(&list)) { - local_bh_disable(); - list_for_each_entry_safe(rq, n, &list, signaling.link) { - dma_fence_signal(&rq->fence); - GEM_BUG_ON(!i915_request_completed(rq)); - i915_request_put(rq); - } - local_bh_enable(); /* kick start the tasklets */ - - /* - * If the engine is saturated we may be continually - * processing completed requests. This angers the - * NMI watchdog if we never let anything else - * have access to the CPU. Let's pretend to be nice - * and relinquish the CPU if we burn through the - * entire RT timeslice! - */ - do_schedule = need_resched(); - } - - if (unlikely(do_schedule)) { - /* Before we sleep, check for a missed seqno */ - if (current->state & TASK_NORMAL && - !list_empty(&b->signals) && - engine->irq_seqno_barrier && - test_and_clear_bit(ENGINE_IRQ_BREADCRUMB, - &engine->irq_posted)) { - engine->irq_seqno_barrier(engine); - intel_engine_wakeup(engine); - } - -sleep: - if (kthread_should_park()) - kthread_parkme(); - - if (unlikely(kthread_should_stop())) - break; - - schedule(); - } - } while (1); - __set_current_state(TASK_RUNNING); - - return 0; -} - -static void insert_signal(struct intel_breadcrumbs *b, - struct i915_request *request, - const u32 seqno) -{ - struct i915_request *iter; - - lockdep_assert_held(&b->rb_lock); - - /* - * A reasonable assumption is that we are called to add signals - * in sequence, as the requests are submitted for execution and - * assigned a global_seqno. This will be the case for the majority - * of internally generated signals (inter-engine signaling). - * - * Out of order waiters triggering random signaling enabling will - * be more problematic, but hopefully rare enough and the list - * small enough that the O(N) insertion sort is not an issue. - */ - - list_for_each_entry_reverse(iter, &b->signals, signaling.link) - if (i915_seqno_passed(seqno, iter->signaling.wait.seqno)) - break; - - list_add(&request->signaling.link, &iter->signaling.link); -} - -bool intel_engine_enable_signaling(struct i915_request *request, bool wakeup) -{ - struct intel_engine_cs *engine = request->engine; - struct intel_breadcrumbs *b = &engine->breadcrumbs; - struct intel_wait *wait = &request->signaling.wait; - u32 seqno; - - /* - * Note that we may be called from an interrupt handler on another - * device (e.g. nouveau signaling a fence completion causing us - * to submit a request, and so enable signaling). As such, - * we need to make sure that all other users of b->rb_lock protect - * against interrupts, i.e. use spin_lock_irqsave. - */ - - /* locked by dma_fence_enable_sw_signaling() (irqsafe fence->lock) */ - GEM_BUG_ON(!irqs_disabled()); - lockdep_assert_held(&request->lock); - - seqno = i915_request_global_seqno(request); - if (!seqno) /* will be enabled later upon execution */ - return true; - - GEM_BUG_ON(wait->seqno); - wait->tsk = b->signaler; - wait->request = request; - wait->seqno = seqno; - - /* - * Add ourselves into the list of waiters, but registering our - * bottom-half as the signaller thread. As per usual, only the oldest - * waiter (not just signaller) is tasked as the bottom-half waking - * up all completed waiters after the user interrupt. - * - * If we are the oldest waiter, enable the irq (after which we - * must double check that the seqno did not complete). - */ - spin_lock(&b->rb_lock); - insert_signal(b, request, seqno); - wakeup &= __intel_engine_add_wait(engine, wait); - spin_unlock(&b->rb_lock); - - if (wakeup) { - wake_up_process(b->signaler); - return !intel_wait_complete(wait); - } - - return true; -} - -void intel_engine_cancel_signaling(struct i915_request *request) -{ - struct intel_engine_cs *engine = request->engine; - struct intel_breadcrumbs *b = &engine->breadcrumbs; - - GEM_BUG_ON(!irqs_disabled()); - lockdep_assert_held(&request->lock); - - if (!READ_ONCE(request->signaling.wait.seqno)) - return; - - spin_lock(&b->rb_lock); - __intel_engine_remove_wait(engine, &request->signaling.wait); - if (fetch_and_zero(&request->signaling.wait.seqno)) - __list_del_entry(&request->signaling.link); - spin_unlock(&b->rb_lock); -} - -int intel_engine_init_breadcrumbs(struct intel_engine_cs *engine) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - struct task_struct *tsk; - - spin_lock_init(&b->rb_lock); - spin_lock_init(&b->irq_lock); - - timer_setup(&b->fake_irq, intel_breadcrumbs_fake_irq, 0); - timer_setup(&b->hangcheck, intel_breadcrumbs_hangcheck, 0); - - INIT_LIST_HEAD(&b->signals); - - /* Spawn a thread to provide a common bottom-half for all signals. - * As this is an asynchronous interface we cannot steal the current - * task for handling the bottom-half to the user interrupt, therefore - * we create a thread to do the coherent seqno dance after the - * interrupt and then signal the waitqueue (via the dma-buf/fence). - */ - tsk = kthread_run(intel_breadcrumbs_signaler, engine, - "i915/signal:%d", engine->id); - if (IS_ERR(tsk)) - return PTR_ERR(tsk); - - b->signaler = tsk; - - return 0; -} - -static void cancel_fake_irq(struct intel_engine_cs *engine) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - - del_timer_sync(&b->fake_irq); /* may queue b->hangcheck */ - del_timer_sync(&b->hangcheck); - clear_bit(engine->id, &engine->i915->gpu_error.missed_irq_rings); -} - -void intel_engine_reset_breadcrumbs(struct intel_engine_cs *engine) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - unsigned long flags; - - spin_lock_irqsave(&b->irq_lock, flags); - - /* - * Leave the fake_irq timer enabled (if it is running), but clear the - * bit so that it turns itself off on its next wake up and goes back - * to the long hangcheck interval if still required. - */ - clear_bit(engine->id, &engine->i915->gpu_error.missed_irq_rings); - - if (b->irq_enabled) - irq_enable(engine); - else - irq_disable(engine); - - /* - * We set the IRQ_BREADCRUMB bit when we enable the irq presuming the - * GPU is active and may have already executed the MI_USER_INTERRUPT - * before the CPU is ready to receive. However, the engine is currently - * idle (we haven't started it yet), there is no possibility for a - * missed interrupt as we enabled the irq and so we can clear the - * immediate wakeup (until a real interrupt arrives for the waiter). - */ - clear_bit(ENGINE_IRQ_BREADCRUMB, &engine->irq_posted); - - spin_unlock_irqrestore(&b->irq_lock, flags); -} - -void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine) -{ - struct intel_breadcrumbs *b = &engine->breadcrumbs; - - /* The engines should be idle and all requests accounted for! */ - WARN_ON(READ_ONCE(b->irq_wait)); - WARN_ON(!RB_EMPTY_ROOT(&b->waiters)); - WARN_ON(!list_empty(&b->signals)); - - if (!IS_ERR_OR_NULL(b->signaler)) - kthread_stop(b->signaler); - - cancel_fake_irq(engine); -} - -#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST) -#include "selftests/intel_breadcrumbs.c" -#endif |