On 2020-06-08 10:01, Luis Chamberlain wrote: > + /* > + * Blktrace needs a debugfs name even for queues that don't register > + * a gendisk, so it lazily registers the debugfs directory. But that > + * can get us into a situation where a SCSI device is found, with no > + * driver for it (yet). Then blktrace is used on the device, creating > + * the debugfs directory, and only after that a driver is loaded. In > + * that case we might already have a debugfs directory registered here. > + * Even worse we could be racing with blktrace to register it. > + */ There are LLD and ULD drivers in the SCSI subsystem. Please mention the driver type explicitly. I assume that you are referring to SCSI ULDs since only SCSI ULD drivers call device_add_disk()? Could the above comment be made shorter by only mentioning that blktrace may have been set up before or concurrently with device_add_disk() and that device_add_disk() calls blk_register_queue()? > case BLKTRACESETUP: > + if (!sdp->device->request_queue->sg_debugfs_dir) > + blk_sg_debugfs_init(sdp->device->request_queue, > + sdp->disk->disk_name); How about moving the sg_debugfs_dir check into blk_sg_debugfs_init()? Thanks, Bart.
