diff options
Diffstat (limited to 'drivers/gpu/drm/i915/intel_ringbuffer.h')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_ringbuffer.h | 25 |
1 files changed, 16 insertions, 9 deletions
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; } |