netdev - Re: [PATCH v2] gianfar: Add I/O barriers when touching buffer descriptor ownership.

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: <9403063bda028d0dfe9e5a05ceea4d7a@kernel.crashing.org>
Date:	Thu, 3 May 2007 01:42:06 +0200
From:	Segher Boessenkool <segher@...nel.crashing.org>
To:	Scott Wood <scottwood@...escale.com>
Cc:	jgarzik@...ox.com, linuxppc-dev@...abs.org,
	Kumar Gala <galak@...nel.crashing.org>, netdev@...r.kernel.org
Subject: Re: [PATCH v2] gianfar: Add I/O barriers when touching buffer descriptor ownership.

>>> And the driver is already ppc-specific; it uses in/out_be32.
>>
>> True, but its hidden behind the gfar_read/write accessors.
>>
>> Your change is a bit more blatant.
>
> Well, Segher doesn't want me to use iobarrier (because it's not I/O).
> Andy doesn't want me to use wmb() (because it's sync).

You should use wmb(), but unfortunately too strong
semantics are required for that (ordering wrt I/O)
so it's a full sync on PowerPC.  I don't believe
a priori that that would be notably slower, but if
actually is, you could use eieio() I suppose since
you say the driver is powerpc specific -- but please
put a comment in the source code then saying why you
don't use wmb() there.


Segher

-
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