Quoting Mika Kuoppala (2019-11-11 10:54:14) > Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes: > > > If we detect a hang in a closed context, just flush all of its requests > > and cancel any remaining execution along the context. Note that after > > closing the context, the last reference to the context may be dropped, > > leaving it only valid under RCU. > > Sound good. But is there a window for userspace to start > to see -EIO if it resubmits to a closed context? Userspace can not submit to a closed context (-ENOENT) as that would be tantamount to a use-after-free kernel bug. > In other words, after userspace doing gem_ctx_destroy(ctx_handle), > we would return -EINVAL due to ctx_handle being stale > earlier than we check for banned status and return -EIO? It's as simple as if the context is closed, it is removed from the file->context_idr and userspace cannot access it. If userspace is racing with itself, there's not much we can do other than protect our references. If userspace succeeds in submitting to the context prior to closing it in another thread, it has the context to continue (and if then hangs, it will be shot down immediately). If it loses that race, it gets an -ENOENT. If it loses that race so badly the context id is replace by a new context, it submits to that new context; which surely will end in tears and GPU hangs, but not our fault and nothing we can do to prevent that. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
