<!DOCTYPE html><html><head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> </head> <body> Am 13.01.25 um 09:43 schrieb Philipp Stanner: <blockquote type="cite" cite="mid:582e10673bb749f18ebf8a18f46ca573df396576.camel@redhat.com">[SNIP] <blockquote type="cite"> <pre class="moz-quote-pre" wrap=""></pre> <blockquote type="cite"> <pre class="moz-quote-pre" wrap="">The handling of NULL values is half-baked. In my opinion, you should define if drm_sched_pick_best() may put a NULL into rq. If your answer is yes, it might put a NULL there; then, there should be a BUG_ON(!entity->rq) after the invocation of drm_sched_entity_select_rq(). If your answer is no, the BUG_ON() should be in drm_sched_pick_best(). </pre> </blockquote> <pre class="moz-quote-pre" wrap=""> Yeah good point. We might not want a BUG_ON(), that is only justified when we prevent further damage (e.g. random data corruption or similar). I suggest using a WARN(!shed, "Submission without activated sheduler!"). This way the system has at least a chance of survival should the scheduler become ready later on. On the other hand the BUG_ON() or the NULL pointer deref should only kill the application thread which is submitting something before the driver is resumed. So that might help to pinpoint where the actually issue is. </pre> </blockquote> <pre class="moz-quote-pre" wrap=""> As I see it the BUG_ON() would just be a more pretty NULL pointer deref. If we agree that this is effectively a misuse of the scheduler API we probably want to add it to make it more pretty, though?</pre> </blockquote> The only alternative I can see is that the scheduler API gracefully handles submits to non-ready schedulers. E.g. that drm_sched_entity_push_job() detects this condition and instead of pushing the job sets and error code and signals the fences. But that might not be a good idea. It just moves the crash from one place to another and in general I fully agree the driver is misusing the scheduler API to do something which won't work and potentially crash the whole system. <blockquote type="cite" cite="mid:582e10673bb749f18ebf8a18f46ca573df396576.camel@redhat.com"> <pre class="moz-quote-pre" wrap="">@Philipp: BTW, I only just discovered this thread by coincidence. Please use get_maintainer. The scheduler currently has 4 maintainers, and none of them is on CC.</pre> </blockquote> Oh good, point I was already wondering why nobody else commented and didn't realized that nobody was on CC. Thanks, Christian. <blockquote type="cite" cite="mid:582e10673bb749f18ebf8a18f46ca573df396576.camel@redhat.com"> <pre class="moz-quote-pre" wrap=""> Danke, P. </pre> <blockquote type="cite"> <pre class="moz-quote-pre" wrap=""> Regards, Christian. </pre> <blockquote type="cite"> <pre class="moz-quote-pre" wrap=""> That helps guys with zero domain knowledge, like me, to figure out how this is all supposed to work. best regards, Philipp </pre> </blockquote> <pre class="moz-quote-pre" wrap=""> </pre> </blockquote> <pre class="moz-quote-pre" wrap=""> </pre> </blockquote> </body> </html>