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drm/i915: Use lockdep_pin_lock() over the construction of the request

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During request construction, we take the timeline->mutex to ensure
exclusive access to the ringbuffer (for command emission) and the
timeline itself (for command ordering). The timeline->mutex should not
be dropped by callers until we release it in i915_request_add().

lockdep provides a pin/unpin lock facility to detect accidental unlocks
inside critical sections, so put it to use for request construction.

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: https://patchwork.freedesktop.org/patch/msgid/20190403082132.327-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2019-04-03 09:21:32 +01:00
parent c2400ec3b6
commit b66ea2c2cf
2 changed files with 15 additions and 0 deletions
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5
drivers/gpu/drm/i915/i915_request.c
View File

@ -751,7 +751,10 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
rq->infix = rq->ring->emit; /* end of header; start of user payload */
/* Check that we didn't interrupt ourselves with a new request */
lockdep_assert_held(&rq->timeline->mutex);
GEM_BUG_ON(rq->timeline->seqno != rq->fence.seqno);
rq->cookie = lockdep_pin_lock(&rq->timeline->mutex);
return rq;
err_unwind:
@ -1070,6 +1073,8 @@ void i915_request_add(struct i915_request *request)
engine->name, request->fence.context, request->fence.seqno);
lockdep_assert_held(&request->timeline->mutex);
lockdep_unpin_lock(&request->timeline->mutex, request->cookie);
trace_i915_request_add(request);
/*

10
drivers/gpu/drm/i915/i915_request.h
View File

@ -26,6 +26,7 @@
#define I915_REQUEST_H
#include <linux/dma-fence.h>
#include <linux/lockdep.h>
#include "i915_gem.h"
#include "i915_scheduler.h"
@ -120,6 +121,15 @@ struct i915_request {
*/
unsigned long rcustate;
/*
* We pin the timeline->mutex while constructing the request to
* ensure that no caller accidentally drops it during construction.
* The timeline->mutex must be held to ensure that only this caller
* can use the ring and manipulate the associated timeline during
* construction.
*/
struct pin_cookie cookie;
/*
* Fences for the various phases in the request's lifetime.
*