Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes: > Around request submission, we protect the call to schedule with a > premption disable loop to prevent set-wedge chaning function pointers s/premption/preemption s/chaning/changing Also RCU read critical sections can be preempted if CONFIG_PREEMPT_RCU so it looks like we should have had explicit preempt_disable() before the rcu_read_lock(), if it is the preempt disable we rely on? -Mika > underneath us. This also prevents the tasklet running on the local CPU, > a trick we use immediately afterwards to forcibly execute the tasklet > after submission. We can combine the two wlog, and ensure that the > tasklet is only executed (on the local CPU) after we complete our > updates to the submission queue (and not after an intermediate, > incomplete update). > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > --- > drivers/gpu/drm/i915/i915_request.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c > index e4cf76ec14a6..88ee444679d4 100644 > --- a/drivers/gpu/drm/i915/i915_request.c > +++ b/drivers/gpu/drm/i915/i915_request.c > @@ -1110,12 +1110,9 @@ void __i915_request_add(struct i915_request *request, bool flush_caches) > * decide whether to preempt the entire chain so that it is ready to > * run at the earliest possible convenience. > */ > - rcu_read_lock(); > + local_bh_disable(); > if (engine->schedule) > engine->schedule(request, &request->ctx->sched); > - rcu_read_unlock(); > - > - local_bh_disable(); > i915_sw_fence_commit(&request->submit); > local_bh_enable(); /* Kick the execlists tasklet if just scheduled */ > > -- > 2.17.0 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
