netdev - Re: [PATCH net-next-2.6] net: inet_add

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]

Date:	Thu, 09 Sep 2010 11:23:57 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jarek Poplawski <jarkao2@...il.com>
Cc:	David Miller <davem@...emloft.net>, jesse@...ira.com,
	netdev@...r.kernel.org
Subject: Re: [PATCH net-next-2.6] net: inet_add_protocol() can use cmpxchg()

Le jeudi 09 septembre 2010 à 09:08 +0000, Jarek Poplawski a écrit :
> xactly, without "after some time" I couldn't tell this
> either. Is seems some barriers might have been changed, but I might
> be wrong. Anyway, it would be nice to have some comment on that in
> the changelog.

Jarek, cmpxchg() is a very strong primitive, as documented
in Documentation/memory-barriers.txt :

<begin of quote>

Any atomic operation that modifies some state in memory and returns information
about the state (old or new) implies an SMP-conditional general memory barrier
(smp_mb()) on each side of the actual operation (with the exception of
explicit lock operations, described later).  These include:

        xchg();
        cmpxchg();
...
These are used for such things as implementing LOCK-class and UNLOCK-class
operations and adjusting reference counters towards object destruction, and as
such the implicit memory barrier effects are necessary.

<end of quote>

Its not needed to document each cmpxchg() use, because of these
strong requirements.

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html