On Wed, Apr 15, 2020 at 08:43:32PM -0700, Bart Van Assche wrote: > On 2020-04-15 18:12, Luis Chamberlain wrote: > > On Wed, Apr 15, 2020 at 07:18:22AM -0700, Bart Van Assche wrote: > >> blk_get_queue() prevents concurrent freeing of struct request_queue but > >> does not prevent concurrent blk_cleanup_queue() calls. > > > > Wouldn't concurrent blk_cleanup_queue() calls be a bug? If so should > > I make it clear that it would be or simply prevent it? > > I think calling blk_cleanup_queue() while the queue refcount > 0 is well > established behavior. At least the SCSI core triggers that behavior > since a very long time. I prefer not to change that behavior. I see. An alternative is to simply check if we already are cleaning up and if so abort early on the blk_cleanup_queue(). That would allow re-entrant calls, and just be a no-op to the additional calls. Or is the re-entrant, two attemps to really do all the work blk_cleanup_queue() expected functionality already? > Regarding patch 3/5: how about dropping that patch? If the queue > refcount can drop to zero while blk_trace_ioctl() is in progress I think > that should be fixed in the block_device_operations.open callback > instead of in blk_trace_ioctl(). I'll take a look, thanks! Luis
