linux-kernel - Re: [PATCH v3 5/7] bdev: add open

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20191105001727.GA29826@infradead.org>
Date:   Mon, 4 Nov 2019 16:17:27 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     Michal Suchanek <msuchanek@...e.de>
Cc:     linux-scsi@...r.kernel.org, Christoph Hellwig <hch@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        "Ewan D. Milne" <emilne@...hat.com>,
        Jonathan Corbet <corbet@....net>, Jens Axboe <axboe@...nel.dk>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        "J. Bruce Fields" <bfields@...hat.com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Eric Biggers <ebiggers@...gle.com>,
        Benjamin Coddington <bcodding@...hat.com>,
        Hannes Reinecke <hare@...e.com>,
        Omar Sandoval <osandov@...com>, Ming Lei <ming.lei@...hat.com>,
        Damien Le Moal <damien.lemoal@....com>,
        Bart Van Assche <bvanassche@....org>,
        Tejun Heo <tj@...nel.org>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v3 5/7] bdev: add open_finish.

Please make sure you CC linux-block if you add block device ops.

On Fri, Oct 25, 2019 at 01:21:42PM +0200, Michal Suchanek wrote:
> Opening a block device may require a long operation such as waiting for
> the cdrom tray to close. Performing this operation with locks held locks
> out other attempts to open the device. These processes waiting to open
> the device are not killable.
> 
> To avoid this issue and still be able to perform time-consuming checks
> at open() time the block device driver can provide open_finish(). If it
> does opening the device proceeds even when an error is returned from
> open(), bd_mutex is released and open_finish() is called. If
> open_finish() succeeds the device is now open, if it fails release() is
> called.
> 
> When -ERESTARTSYS is returned from open() blkdev_get may loop without
> calling open_finish(). On -ERESTARTSYS open_finish() is not called.
> 
> Move a ret = 0 assignment up in the if/else branching to avoid returning
> -ENXIO. Previously the return value was ignored on the unhandled branch.

Still a complete nack for splitting a fundamental operation over two
ops, especially just for working around a piece of buggy software.