diff options
| -rw-r--r-- | drivers/gpu/drm/i915/i915_drv.h | 4 | ||||
| -rw-r--r-- | drivers/gpu/drm/i915/intel_breadcrumbs.c | 22 | ||||
| -rw-r--r-- | drivers/gpu/drm/i915/intel_ringbuffer.c | 2 | ||||
| -rw-r--r-- | drivers/gpu/drm/i915/intel_ringbuffer.h | 25 |
4 files changed, 27 insertions, 26 deletions
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 54f789c75aa1..2cb91ffbbfa2 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -3849,7 +3849,7 @@ static inline bool __i915_request_irq_complete(struct drm_i915_gem_request *req) * is woken. */ if (engine->irq_seqno_barrier && - READ_ONCE(engine->breadcrumbs.irq_seqno_bh) == current && + rcu_access_pointer(engine->breadcrumbs.irq_seqno_bh) == current && cmpxchg_relaxed(&engine->breadcrumbs.irq_posted, 1, 0)) { struct task_struct *tsk; @@ -3874,7 +3874,7 @@ static inline bool __i915_request_irq_complete(struct drm_i915_gem_request *req) * irq_posted == false but we are still running). */ rcu_read_lock(); - tsk = READ_ONCE(engine->breadcrumbs.irq_seqno_bh); + tsk = rcu_dereference(engine->breadcrumbs.irq_seqno_bh); if (tsk && tsk != current) /* Note that if the bottom-half is changed as we * are sending the wake-up, the new bottom-half will diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c index 7be9af1d5424..2491e4c1eaf0 100644 --- a/drivers/gpu/drm/i915/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c @@ -71,10 +71,8 @@ static void intel_breadcrumbs_fake_irq(unsigned long data) * every jiffie in order to kick the oldest waiter to do the * coherent seqno check. */ - rcu_read_lock(); if (intel_engine_wakeup(engine)) mod_timer(&engine->breadcrumbs.fake_irq, jiffies + 1); - rcu_read_unlock(); } static void irq_enable(struct intel_engine_cs *engine) @@ -234,7 +232,7 @@ static bool __intel_engine_add_wait(struct intel_engine_cs *engine, } rb_link_node(&wait->node, parent, p); rb_insert_color(&wait->node, &b->waiters); - GEM_BUG_ON(!first && !b->irq_seqno_bh); + GEM_BUG_ON(!first && !rcu_access_pointer(b->irq_seqno_bh)); if (completed) { struct rb_node *next = rb_next(completed); @@ -244,7 +242,7 @@ static bool __intel_engine_add_wait(struct intel_engine_cs *engine, GEM_BUG_ON(first); b->timeout = wait_timeout(); b->first_wait = to_wait(next); - smp_store_mb(b->irq_seqno_bh, b->first_wait->tsk); + rcu_assign_pointer(b->irq_seqno_bh, b->first_wait->tsk); /* As there is a delay between reading the current * seqno, processing the completed tasks and selecting * the next waiter, we may have missed the interrupt @@ -271,7 +269,7 @@ static bool __intel_engine_add_wait(struct intel_engine_cs *engine, GEM_BUG_ON(rb_first(&b->waiters) != &wait->node); b->timeout = wait_timeout(); b->first_wait = wait; - smp_store_mb(b->irq_seqno_bh, wait->tsk); + rcu_assign_pointer(b->irq_seqno_bh, wait->tsk); /* 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, @@ -282,7 +280,7 @@ static bool __intel_engine_add_wait(struct intel_engine_cs *engine, */ __intel_breadcrumbs_enable_irq(b); } - GEM_BUG_ON(!b->irq_seqno_bh); + GEM_BUG_ON(!rcu_access_pointer(b->irq_seqno_bh)); GEM_BUG_ON(!b->first_wait); GEM_BUG_ON(rb_first(&b->waiters) != &b->first_wait->node); @@ -337,7 +335,7 @@ void intel_engine_remove_wait(struct intel_engine_cs *engine, const int priority = wakeup_priority(b, wait->tsk); struct rb_node *next; - GEM_BUG_ON(b->irq_seqno_bh != wait->tsk); + GEM_BUG_ON(rcu_access_pointer(b->irq_seqno_bh) != wait->tsk); /* We are the current bottom-half. Find the next candidate, * the first waiter in the queue on the remaining oldest @@ -381,13 +379,13 @@ void intel_engine_remove_wait(struct intel_engine_cs *engine, */ b->timeout = wait_timeout(); b->first_wait = to_wait(next); - smp_store_mb(b->irq_seqno_bh, b->first_wait->tsk); + rcu_assign_pointer(b->irq_seqno_bh, b->first_wait->tsk); if (b->first_wait->seqno != wait->seqno) __intel_breadcrumbs_enable_irq(b); - wake_up_process(b->irq_seqno_bh); + wake_up_process(b->first_wait->tsk); } else { b->first_wait = NULL; - WRITE_ONCE(b->irq_seqno_bh, NULL); + rcu_assign_pointer(b->irq_seqno_bh, NULL); __intel_breadcrumbs_disable_irq(b); } } else { @@ -401,7 +399,7 @@ out_unlock: GEM_BUG_ON(b->first_wait == wait); GEM_BUG_ON(rb_first(&b->waiters) != (b->first_wait ? &b->first_wait->node : NULL)); - GEM_BUG_ON(!b->irq_seqno_bh ^ RB_EMPTY_ROOT(&b->waiters)); + GEM_BUG_ON(!rcu_access_pointer(b->irq_seqno_bh) ^ RB_EMPTY_ROOT(&b->waiters)); spin_unlock(&b->lock); } @@ -598,11 +596,9 @@ unsigned int intel_kick_waiters(struct drm_i915_private *i915) * RCU lock, i.e. as we call wake_up_process() we must be holding the * rcu_read_lock(). */ - rcu_read_lock(); for_each_engine(engine, i915) if (unlikely(intel_engine_wakeup(engine))) mask |= intel_engine_flag(engine); - rcu_read_unlock(); return mask; } diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index e08a1e1b04e4..16b726fe33eb 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -2410,9 +2410,7 @@ void intel_engine_init_seqno(struct intel_engine_cs *engine, u32 seqno) /* After manually advancing the seqno, fake the interrupt in case * there are any waiters for that seqno. */ - rcu_read_lock(); intel_engine_wakeup(engine); - rcu_read_unlock(); } static void gen6_bsd_submit_request(struct drm_i915_gem_request *request) diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h index c7a6db310f9f..ea2735144b2a 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.h +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h @@ -171,7 +171,7 @@ struct intel_engine_cs { * the overhead of waking that client is much preferred. */ struct intel_breadcrumbs { - struct task_struct *irq_seqno_bh; /* bh for user interrupts */ + struct task_struct __rcu *irq_seqno_bh; /* bh for interrupts */ bool irq_posted; spinlock_t lock; /* protects the lists of requests */ @@ -539,25 +539,32 @@ void intel_engine_remove_wait(struct intel_engine_cs *engine, struct intel_wait *wait); void intel_engine_enable_signaling(struct drm_i915_gem_request *request); -static inline bool intel_engine_has_waiter(struct intel_engine_cs *engine) +static inline bool intel_engine_has_waiter(const struct intel_engine_cs *engine) { - return READ_ONCE(engine->breadcrumbs.irq_seqno_bh); + return rcu_access_pointer(engine->breadcrumbs.irq_seqno_bh); } -static inline bool intel_engine_wakeup(struct intel_engine_cs *engine) +static inline bool intel_engine_wakeup(const struct intel_engine_cs *engine) { bool wakeup = false; - struct task_struct *tsk = READ_ONCE(engine->breadcrumbs.irq_seqno_bh); + /* Note that for this not to dangerously chase a dangling pointer, - * the caller is responsible for ensure that the task remain valid for - * wake_up_process() i.e. that the RCU grace period cannot expire. + * we must hold the rcu_read_lock here. * * Also note that tsk is likely to be in !TASK_RUNNING state so an * early test for tsk->state != TASK_RUNNING before wake_up_process() * is unlikely to be beneficial. */ - if (tsk) - wakeup = wake_up_process(tsk); + if (intel_engine_has_waiter(engine)) { + struct task_struct *tsk; + + rcu_read_lock(); + tsk = rcu_dereference(engine->breadcrumbs.irq_seqno_bh); + if (tsk) + wakeup = wake_up_process(tsk); + rcu_read_unlock(); + } + return wakeup; } |