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Message-ID: <20120228181132.13f1088c@stein> Date: Tue, 28 Feb 2012 18:11:32 +0100 From: Stefan Richter <stefanr@...6.in-berlin.de> To: James Bottomley <James.Bottomley@...senPartnership.com> Cc: Arnd Bergmann <arnd@...db.de>, Jens Axboe <axboe@...nel.dk>, linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] [SCSI] sr: fix multi-drive performance, remove BKL replacement On Feb 28 James Bottomley wrote: > On Tue, 2012-02-28 at 16:42 +0000, Arnd Bergmann wrote: > > I took another look and I believe the cdi->use_count in > > cdrom_open/cdrom_release still requires some protection that is > > currently provided by sr_mutex. > > So I think this is fine ... it's protected by the bdev->bd_mutex. > > > Some parts of cdrom_ioctl also > > access this variable and things like cdi->options or cdi->keeplocked. > > This would be problematic because we no longer lock the ioctl. > > > I could imagine that you can get rid of the mutex if you turn those > > into atomics and bitops, but there may be other parts of cdrom_device_info > > that need locking. A safer option to solve the performance problems > > could be to replace sr_mutex with a per-device mutex inside of > > cdrom_device_info. > > I'd say the latter. Thanks Arnd and James, I will pursue this when I get the time. -- Stefan Richter -=====-===-- --=- ===-- http://arcgraph.de/sr/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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