linux-kernel - Re: [rfc] "fair" rw spinlocks

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: <20091130162058.GA6762@linux.vnet.ibm.com>
Date:	Mon, 30 Nov 2009 08:20:58 -0800
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Nick Piggin <npiggin@...e.de>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [rfc] "fair" rw spinlocks

On Mon, Nov 30, 2009 at 08:55:57AM +0100, Nick Piggin wrote:
> On Sat, Nov 28, 2009 at 09:30:18AM -0800, Linus Torvalds wrote:
> > So as far as I can tell, we have only one real user of rwlocks where 
> > livelocks might be relevant, but that one real user absolutely _requires_ 
> > the unfair behavior.
> 
> Yes, although the behaviour required is that it can be recursively
> acquired. So we could still have a lock that disallows new non recursive
> read acquires when there is a pending write locker.
> 
> RCU seems nicer, but tasklist lock locking scares me so I wanted to fix
> it the easy way :)

Having a livelock-free tasklist lock would certainly make it easier
to apply things like RCU on a code-path-by-code-path basis as needed.
Much less scary than a big-bang rip-and-replace.

							Thanx, Paul
--
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/