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drm/i915: Defer semaphore priority bumping to a workqueue 

Since the semaphore fence may be signaled from inside an interrupt
handler from inside a request holding its request->lock, we cannot then
enter into the engine->active.lock for processing the semaphore priority
bump as we may traverse our call tree and end up on another held
request.

CPU 0:
[ 2243.218864]  _raw_spin_lock_irqsave+0x9a/0xb0
[ 2243.218867]  i915_schedule_bump_priority+0x49/0x80 [i915]
[ 2243.218869]  semaphore_notify+0x6d/0x98 [i915]
[ 2243.218871]  __i915_sw_fence_complete+0x61/0x420 [i915]
[ 2243.218874]  ? kmem_cache_free+0x211/0x290
[ 2243.218876]  i915_sw_fence_complete+0x58/0x80 [i915]
[ 2243.218879]  dma_i915_sw_fence_wake+0x3e/0x80 [i915]
[ 2243.218881]  signal_irq_work+0x571/0x690 [i915]
[ 2243.218883]  irq_work_run_list+0xd7/0x120
[ 2243.218885]  irq_work_run+0x1d/0x50
[ 2243.218887]  smp_irq_work_interrupt+0x21/0x30
[ 2243.218889]  irq_work_interrupt+0xf/0x20

CPU 1:
[ 2242.173107]  _raw_spin_lock+0x8f/0xa0
[ 2242.173110]  __i915_request_submit+0x64/0x4a0 [i915]
[ 2242.173112]  __execlists_submission_tasklet+0x8ee/0x2120 [i915]
[ 2242.173114]  ? i915_sched_lookup_priolist+0x1e3/0x2b0 [i915]
[ 2242.173117]  execlists_submit_request+0x2e8/0x2f0 [i915]
[ 2242.173119]  submit_notify+0x8f/0xc0 [i915]
[ 2242.173121]  __i915_sw_fence_complete+0x61/0x420 [i915]
[ 2242.173124]  ? _raw_spin_unlock_irqrestore+0x39/0x40
[ 2242.173137]  i915_sw_fence_complete+0x58/0x80 [i915]
[ 2242.173140]  i915_sw_fence_commit+0x16/0x20 [i915]

Closes: https://gitlab.freedesktop.org/drm/intel/issues/1318
Fixes: b7404c7ecb ("drm/i915: Bump ready tasks ahead of busywaits")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: <stable@vger.kernel.org> # v5.2+
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200310101720.9944-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2020-03-10 10:17:20 +00:00
parent 75e675f81f
commit 209df10bb4
2 changed files with 19 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
drivers/gpu/drm/i915/i915_request.c
View File

@ -588,19 +588,31 @@ submit_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
return NOTIFY_DONE;
}
static void irq_semaphore_cb(struct irq_work *wrk)
{
struct i915_request *rq =
container_of(wrk, typeof(*rq), semaphore_work);
i915_schedule_bump_priority(rq, I915_PRIORITY_NOSEMAPHORE);
i915_request_put(rq);
}
static int __i915_sw_fence_call
semaphore_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
{
struct i915_request *request =
container_of(fence, typeof(*request), semaphore);
struct i915_request *rq = container_of(fence, typeof(*rq), semaphore);
switch (state) {
case FENCE_COMPLETE:
i915_schedule_bump_priority(request, I915_PRIORITY_NOSEMAPHORE);
if (!(READ_ONCE(rq->sched.attr.priority) & I915_PRIORITY_NOSEMAPHORE)) {
i915_request_get(rq);
init_irq_work(&rq->semaphore_work, irq_semaphore_cb);
irq_work_queue(&rq->semaphore_work);
}
break;
case FENCE_FREE:
i915_request_put(request);
i915_request_put(rq);
break;
}
@ -1400,9 +1412,9 @@ void __i915_request_queue(struct i915_request *rq,
* decide whether to preempt the entire chain so that it is ready to
* run at the earliest possible convenience.
*/
i915_sw_fence_commit(&rq->semaphore);
if (attr && rq->engine->schedule)
rq->engine->schedule(rq, attr);
i915_sw_fence_commit(&rq->semaphore);
i915_sw_fence_commit(&rq->submit);
}

2
drivers/gpu/drm/i915/i915_request.h
View File

@ -26,6 +26,7 @@
#define I915_REQUEST_H
#include <linux/dma-fence.h>
#include <linux/irq_work.h>
#include <linux/lockdep.h>
#include "gem/i915_gem_context_types.h"
@ -208,6 +209,7 @@ struct i915_request {
};
struct list_head execute_cb;
struct i915_sw_fence semaphore;
struct irq_work semaphore_work;
/*
* A list of everyone we wait upon, and everyone who waits upon us.