From: Jeff Garzik <jeff@garzik.org>
To: Scott Wood <scottwood@freescale.com>
Cc: netdev@vger.kernel.org, linuxppc-dev@ozlabs.org
Subject: Re: [PATCH] gianfar: Add I/O barriers when touching buffer descriptor ownership.
Date: Thu, 17 May 2007 20:45:49 -0400 [thread overview]
Message-ID: <464CF73D.9050505@garzik.org> (raw)
In-Reply-To: <20070516200659.GA23548@ld0162-tx32.am.freescale.net>
Scott Wood wrote:
> The hardware must not see that is given ownership of a buffer until it is
> completely written, and when the driver receives ownership of a buffer,
> it must ensure that any other reads to the buffer reflect its final
> state. Thus, I/O barriers are added where required.
>
> Without this patch, I have observed GCC reordering the setting of
> bdp->length and bdp->status in gfar_new_skb. Hardware reordering
> was also theoretically possible.
>
> Signed-off-by: Scott Wood <scottwood@freescale.com>
> ---
> I've added the requested comments to the source code about
> the use of eieio(). Jeff, please consider for 2.6.22, as it
> fixes a bug that has been observed.
>
> drivers/net/gianfar.c | 11 +++++++++++
> 1 files changed, 11 insertions(+), 0 deletions(-)
applied
next prev parent reply other threads:[~2007-05-18 0:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-16 20:06 [PATCH] gianfar: Add I/O barriers when touching buffer descriptor ownership Scott Wood
2007-05-18 0:45 ` Jeff Garzik [this message]
-- strict thread matches above, loose matches on Subject: below --
2007-05-01 16:55 Scott Wood
2007-05-02 0:54 ` Segher Boessenkool
2007-05-02 0:54 ` Segher Boessenkool
2007-05-02 16:04 ` Scott Wood
2007-05-02 16:04 ` Scott Wood
2007-05-02 18:05 ` Segher Boessenkool
2007-05-02 18:05 ` Segher Boessenkool
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