drm/i915/execlists: Protect peeking at execlists->active
authorChris Wilson <chris@chris-wilson.co.uk>
Wed, 9 Oct 2019 10:09:54 +0000 (11:09 +0100)
committerRodrigo Vivi <rodrigo.vivi@intel.com>
Wed, 9 Oct 2019 21:39:30 +0000 (14:39 -0700)
commit749085a2131f7e328dd33635eb3d37b519f451f9
tree6c79d26a978e6cf59984224aebc03a3f89d6aae0
parent68184eb7b09640ac84aeefe31923d70d1fa07292
drm/i915/execlists: Protect peeking at execlists->active

Now that we dropped the engine->active.lock serialisation from around
process_csb(), direct submission can run concurrently to the interrupt
handler. As such execlists->active may be advanced as we dequeue,
dropping the reference to the request. We need to employ our RCU request
protection to ensure that the request is not freed too early.

Fixes: df403069029d ("drm/i915/execlists: Lift process_csb() out of the irq-off spinlock")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191009100955.21477-1-chris@chris-wilson.co.uk
(cherry picked from commit c949ae431467764277cdd88d7c26ff963a9db40a)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
drivers/gpu/drm/i915/gt/intel_lrc.c