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author | Chris Wilson <chris@chris-wilson.co.uk> | 2017-02-23 07:44:15 +0000 |
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committer | Chris Wilson <chris@chris-wilson.co.uk> | 2017-02-23 14:49:34 +0000 |
commit | cced5e2f098d9db26cf4119e309068b79cca1274 (patch) | |
tree | 5005a6f9052faf424014faae48c6cffe771ad93b /drivers/gpu/drm/i915/intel_breadcrumbs.c | |
parent | 754c9fd5764909bc7c3ba9779355d55cb357be8a (diff) | |
download | op-kernel-dev-cced5e2f098d9db26cf4119e309068b79cca1274.zip op-kernel-dev-cced5e2f098d9db26cf4119e309068b79cca1274.tar.gz |
drm/i915: Take a reference whilst processing the signaler request
The plan in the near-future is to allow requests to be removed from the
signaler. We can no longer then rely on holding a reference to the
request for the duration it is in the signaling tree, and instead must
obtain a reference to the request for the current operation using RCU.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170223074422.4125-10-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu/drm/i915/intel_breadcrumbs.c')
-rw-r--r-- | drivers/gpu/drm/i915/intel_breadcrumbs.c | 22 |
1 files changed, 15 insertions, 7 deletions
diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c index d5bf4c0..a35d59d 100644 --- a/drivers/gpu/drm/i915/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c @@ -496,7 +496,11 @@ static int intel_breadcrumbs_signaler(void *arg) * need to wait for a new interrupt from the GPU or for * a new client. */ - request = READ_ONCE(b->first_signal); + rcu_read_lock(); + request = rcu_dereference(b->first_signal); + if (request) + request = i915_gem_request_get_rcu(request); + rcu_read_unlock(); if (signal_complete(request)) { local_bh_disable(); dma_fence_signal(&request->fence); @@ -515,24 +519,28 @@ static int intel_breadcrumbs_signaler(void *arg) * the oldest before picking the next one. */ spin_lock_irq(&b->lock); - if (request == b->first_signal) { + if (request == rcu_access_pointer(b->first_signal)) { struct rb_node *rb = rb_next(&request->signaling.node); - b->first_signal = rb ? to_signaler(rb) : NULL; + rcu_assign_pointer(b->first_signal, + rb ? to_signaler(rb) : NULL); } rb_erase(&request->signaling.node, &b->signals); spin_unlock_irq(&b->lock); i915_gem_request_put(request); } else { - if (kthread_should_stop()) + if (kthread_should_stop()) { + GEM_BUG_ON(request); break; + } schedule(); if (kthread_should_park()) kthread_parkme(); } + i915_gem_request_put(request); } while (1); __set_current_state(TASK_RUNNING); @@ -597,7 +605,7 @@ void intel_engine_enable_signaling(struct drm_i915_gem_request *request) rb_link_node(&request->signaling.node, parent, p); rb_insert_color(&request->signaling.node, &b->signals); if (first) - smp_store_mb(b->first_signal, request); + rcu_assign_pointer(b->first_signal, request); spin_unlock(&b->lock); @@ -670,7 +678,7 @@ void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine) /* The engines should be idle and all requests accounted for! */ WARN_ON(READ_ONCE(b->first_wait)); WARN_ON(!RB_EMPTY_ROOT(&b->waiters)); - WARN_ON(READ_ONCE(b->first_signal)); + WARN_ON(rcu_access_pointer(b->first_signal)); WARN_ON(!RB_EMPTY_ROOT(&b->signals)); if (!IS_ERR_OR_NULL(b->signaler)) @@ -691,7 +699,7 @@ bool intel_breadcrumbs_busy(struct intel_engine_cs *engine) busy |= intel_engine_flag(engine); } - if (b->first_signal) { + if (rcu_access_pointer(b->first_signal)) { wake_up_process(b->signaler); busy |= intel_engine_flag(engine); } |