linux-kernel - Re: [PATCH] SH/Dreamcast - add support for GD-Rom device

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 for Android: free password hash cracker in your pocket

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

Message-Id: <1198759779.6170.4.camel@localhost.localdomain>
Date:	Thu, 27 Dec 2007 12:49:39 +0000
From:	Adrian McMenamin <adrian@...golddream.dyndns.info>
To:	Paul Mundt <lethal@...ux-sh.org>
Cc:	Adrian McMenamin <lkmladrian@...il.com>,
	Jens Axboe <jens.axboe@...cle.com>,
	linux-kernel@...r.kernel.org, linux-sh@...r.kernel.org
Subject: Re: [PATCH] SH/Dreamcast - add support for GD-Rom device


On Thu, 2007-12-27 at 17:18 +0900, Paul Mundt wrote:
> On Thu, Dec 27, 2007 at 01:26:47AM +0000, Adrian McMenamin wrote:

> 
> > +		/* now seek to take the request spinlock
> > + 		 * before handling ending the request */
> > +		spin_lock(&gdrom_lock);
> > +		list_del_init(&req->queuelist);
> > +		blk_requeue_request(gd.gdrom_rq, req);
> > +		if (err)
> > +			end_request(req, 0);
> > +		else
> > +			end_request(req, 1);
> > +	}
> > +	spin_unlock(&gdrom_lock);
> > +	kfree(read_command);
> > +}	
> > +
> This locking is all over the place. What is this lock supposed to be
> accomplishing?
> -

I have to hold the lock to access the request queue. As the linked list
of deferred requests is under the control of code also protected by the
lock, it is also held to ensure manipulation of that list is serialised.

The first step of the loop manipulates that linked list - so it is held
as we re-iterate over the loop.

This is pretty much the way Jens recommended I do it.

--
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/