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drm/i915/breadcrumbs: Assert that we do not shortcut the current bottom-half 

We need to ensure that we always serialize updates to the bottom-half
using the breadcrumbs.irq_lock so that we don't race with a concurrent
interrupt handler. This is most important just prior to leaving the
waiter (when the intel_wait will be overwritten), so make sure we are
not the current bottom-half when skipping the irq locks.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170315210726.12095-4-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2017-03-15 21:07:25 +00:00
parent a5cae7b8ed
commit 908a6cbf84
1 changed files with 4 additions and 1 deletions
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5
drivers/gpu/drm/i915/intel_breadcrumbs.c
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@ -287,6 +287,7 @@ 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.
@ -512,8 +513,10 @@ void intel_engine_remove_wait(struct intel_engine_cs *engine,
* the tree by the bottom-half to avoid contention on the spinlock
* by the herd.
*/
if (RB_EMPTY_NODE(&wait->node))
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);