Don`t simplely disable local interrupt delivery of CPU hardware irq, should race the region inside signal_irq_work, include intel_breadcrumbs_disarm_irq/intel_breadcrumbs_arm_irq.

RT complains about might sleep inside signal_irq_work() because spin_lock will be invoked after disabling interrupts.

Thanks to Tvrtko Ursulin for his expert opinions and suggestions.

BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:969 #0: ffff89c4c00ca970 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1cf/0x6d0 #1: ffffa433c1f53e60 ((work_completion)(&engine->retire_work)){+.+.}-{0:0}, at: process_one_work+0x1cf 0x6d #2: ffff89c4ccb0a0a8 (kernel_context){+.+.}-{0:0}, at: engine_retire+0x62/0x110 [i915] #3: ffff89c4cf682300 (wakeref.mutex#3){+.+.}-{0:0}, at: __intel_wakeref_put_last+0x20/0x60 [i915] #4: ffff89c4ccb08398 (&b->irq_lock){+.+.}-{0:0}, at: intel_breadcrumbs_disarm_irq+0x20/0xd0 [i915] irq event stamp: 2126 hardirqs last enabled at (2125): [<ffffffffbb134739>] cancel_delayed_work+0xa9/0xc0 hardirqs last disabled at (2126): [<ffffffffc0507fe6>] __intel_breadcrumbs_park+0x76/0x80 [i915] softirqs last enabled at (0): [<ffffffffbb1099ce>] copy_process+0x63e/0x1630 softirqs last disabled at (0): [<0000000000000000>] 0x0 CPU: 3 PID: 281 Comm: kworker/3:3 Not tainted 5.10.27-rt34-yocto-preempt-rt #1 Hardware name: Intel(R) Client Systems NUC7i5DNKE/NUC7i5DNB, BIOS DNKBLi5v.86A.0064.2019.0523.1933 05/23 2019 Workqueue: events engine_retire [i915] Call Trace: show_stack+0x52/0x58 dump_stack+0x7d/0x9f ___might_sleep.cold+0xe3/0xf4 rt_spin_lock+0x3f/0xc0 ? intel_breadcrumbs_disarm_irq+0x20/0xd0 [i915] intel_breadcrumbs_disarm_irq+0x20/0xd0 [i915] signal_irq_work+0x241/0x660 [i915] ? __this_cpu_preempt_check+0x13/0x20 ? lockdep_hardirqs_off+0x106/0x120 __intel_breadcrumbs_park+0x3f/0x80 [i915] __engine_park+0xbd/0xe0 [i915] ____intel_wakeref_put_last+0x22/0x60 [i915] __intel_wakeref_put_last+0x50/0x60 [i915] intel_context_exit_engine+0x5f/0x70 [i915] i915_request_retire+0x139/0x2d0 [i915] engine_retire+0xb0/0x110 [i915] process_one_work+0x26d/0x6d0 worker_thread+0x53/0x330 kthread+0x1b0/0x1d0 ? process_one_work+0x6d0/0x6d0 ? __kthread_parkme+0xc0/0xc0 ret_from_fork+0x22/0x30

Fixes: 9d5612ca165a ("drm/i915/gt: Defer enabling the breadcrumb interrupt to after submission") Signed-off-by: Jun Miao jun.miao@windriver.com --- drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c index 34a645d..01eb18e 100644 --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c @@ -82,13 +82,15 @@ static void __intel_breadcrumbs_arm_irq(struct intel_breadcrumbs *b)

static void intel_breadcrumbs_arm_irq(struct intel_breadcrumbs *b) { + unsigned long flags; + if (!b->irq_engine) return;

- spin_lock(&b->irq_lock); + spin_lock_irqsave(&b->irq_lock, flags); if (!b->irq_armed) __intel_breadcrumbs_arm_irq(b); - spin_unlock(&b->irq_lock); + spin_unlock_irqrestore(&b->irq_lock, flags); }

static void __intel_breadcrumbs_disarm_irq(struct intel_breadcrumbs *b) @@ -103,10 +105,12 @@ static void __intel_breadcrumbs_disarm_irq(struct intel_breadcrumbs *b)

static void intel_breadcrumbs_disarm_irq(struct intel_breadcrumbs *b) { - spin_lock(&b->irq_lock); + unsigned long flags; + + spin_lock_irqsave(&b->irq_lock, flags); if (b->irq_armed) __intel_breadcrumbs_disarm_irq(b); - spin_unlock(&b->irq_lock); + spin_unlock_irqrestore(&b->irq_lock, flags); }

static void add_signaling_context(struct intel_breadcrumbs *b, @@ -200,6 +204,7 @@ static void signal_irq_work(struct irq_work *work) const ktime_t timestamp = ktime_get(); struct llist_node *signal, *sn; struct intel_context *ce; + unsigned long flags;

signal = NULL; if (unlikely(!llist_empty(&b->signaled_requests))) @@ -278,11 +283,11 @@ static void signal_irq_work(struct irq_work *work) llist_entry(signal, typeof(*rq), signal_node); struct list_head cb_list;

- spin_lock(&rq->lock); + spin_lock_irqsave(&rq->lock, flags); list_replace(&rq->fence.cb_list, &cb_list); __dma_fence_signal__timestamp(&rq->fence, timestamp); __dma_fence_signal__notify(&rq->fence, &cb_list); - spin_unlock(&rq->lock); + spin_unlock_irqrestore(&rq->lock, flags);

i915_request_put(rq); } @@ -337,9 +342,7 @@ void __intel_breadcrumbs_park(struct intel_breadcrumbs *b) /* Kick the work once more to drain the signalers, and disarm the irq */ irq_work_sync(&b->irq_work); while (READ_ONCE(b->irq_armed) && !atomic_read(&b->active)) { - local_irq_disable(); signal_irq_work(&b->irq_work); - local_irq_enable(); cond_resched(); } }