On 20/11/14 06:34, Christoph Hellwig wrote: > Wakko, any chance you could resend a patch to remove the mutex from the > ioctl path? I'm trying out some local changes which removes the ex-BKL mutex from sr_block_ioctl() in sr.c, and instead uses a per-drive mutex which I've added to cdrom_device_info (as per Arnd Bergmann/ James Bottomley's discussion here https://lkml.org/lkml/2012/2/28/305 ). This seems to work in a quick test testing (simultaneous cdparanoia on 8-or-so drives took ~10 minutes, whereas last time I tried that it took more than 18 hours), but I've been short on time to do much more. At first inspection, it looks like it's just the cdrom-specific ioctls in drivers/cdrom/cdrom.c which aren't safely preemptible (my conclusion based on the fact that scsi_ioctl etc. is called elsewhere without locking (e.g. from /dev/sg and /dev/sd devices - I haven't looked at ). As a result, I was wondering about moving the mutex_lock / unlock, so that they wrap just the cdrom-specific ioctl calls instead, although I suspect there won't be a huge performance benefit from doing so, it would have the advantage that all the code related to the new mutex to be moved into cdrom.c Hopefully I'll grab a bit of time to work on this later this week, and post a patch. Cheers, Tim. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
