Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes: > We control b->irq_enabled inside the b->irq_lock, but we check before > entering the spinlock whether or not the interrupt is currently > unmasked. > > [ 1511.735208] BUG: KCSAN: data-race in __intel_breadcrumbs_disarm_irq [i915] / intel_engine_disarm_breadcrumbs [i915] > [ 1511.735231] > [ 1511.735242] write to 0xffff8881f75fc214 of 1 bytes by interrupt on cpu 2: > [ 1511.735440] __intel_breadcrumbs_disarm_irq+0x4b/0x160 [i915] > [ 1511.735635] signal_irq_work+0x337/0x710 [i915] > [ 1511.735652] irq_work_run_list+0xd7/0x110 > [ 1511.735666] irq_work_run+0x1d/0x50 > [ 1511.735681] smp_irq_work_interrupt+0x21/0x30 > [ 1511.735701] irq_work_interrupt+0xf/0x20 > [ 1511.735722] __do_softirq+0x6f/0x206 > [ 1511.735736] irq_exit+0xcd/0xe0 > [ 1511.735756] do_IRQ+0x44/0xc0 > [ 1511.735773] ret_from_intr+0x0/0x1c > [ 1511.735787] schedule+0x0/0xb0 > [ 1511.735803] worker_thread+0x194/0x670 > [ 1511.735823] kthread+0x19a/0x1e0 > [ 1511.735837] ret_from_fork+0x1f/0x30 > [ 1511.735848] > [ 1511.735867] read to 0xffff8881f75fc214 of 1 bytes by task 432 on cpu 1: > [ 1511.736068] intel_engine_disarm_breadcrumbs+0x22/0x80 [i915] > [ 1511.736263] __engine_park+0x107/0x5d0 [i915] > [ 1511.736453] ____intel_wakeref_put_last+0x44/0x90 [i915] > [ 1511.736648] __intel_wakeref_put_last+0x5a/0x70 [i915] > [ 1511.736842] intel_context_exit_engine+0xf2/0x100 [i915] > [ 1511.737044] i915_request_retire+0x6b2/0x770 [i915] > [ 1511.737244] retire_requests+0x7a/0xd0 [i915] > [ 1511.737438] intel_gt_retire_requests_timeout+0x3a7/0x6f0 [i915] > [ 1511.737633] i915_drop_caches_set+0x1e7/0x260 [i915] > [ 1511.737650] simple_attr_write+0xfa/0x110 > [ 1511.737665] full_proxy_write+0x94/0xc0 > [ 1511.737679] __vfs_write+0x4b/0x90 > [ 1511.737697] vfs_write+0xfc/0x280 > [ 1511.737718] ksys_write+0x78/0x100 > [ 1511.737732] __x64_sys_write+0x44/0x60 > [ 1511.737751] do_syscall_64+0x6e/0x2c0 > [ 1511.737769] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx> On these parts, avoiding the cost of spinlock is warranted. Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx> > --- > drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c > index cbad7fe722ce..cbedba857d43 100644 > --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c > +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c > @@ -64,7 +64,7 @@ static void __intel_breadcrumbs_disarm_irq(struct intel_breadcrumbs *b) > if (!--b->irq_enabled) > irq_disable(engine); > > - b->irq_armed = false; > + WRITE_ONCE(b->irq_armed, false); > intel_gt_pm_put_async(engine->gt); > } > > @@ -73,7 +73,7 @@ void intel_engine_disarm_breadcrumbs(struct intel_engine_cs *engine) > struct intel_breadcrumbs *b = &engine->breadcrumbs; > unsigned long flags; > > - if (!b->irq_armed) > + if (!READ_ONCE(b->irq_armed)) > return; > > spin_lock_irqsave(&b->irq_lock, flags); > @@ -233,7 +233,7 @@ static bool __intel_breadcrumbs_arm_irq(struct intel_breadcrumbs *b) > * which we can add a new waiter and avoid the cost of re-enabling > * the irq. > */ > - b->irq_armed = true; > + WRITE_ONCE(b->irq_armed, true); > > /* > * Since we are waiting on a request, the GPU should be busy > -- > 2.20.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
