linux-kernel - Re: [PATCH v3 06/10] net/macb: clean up ring buffer logic

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:	Tue, 30 Oct 2012 11:22:51 -0700
From:	Håvard Skinnemoen <havard@...nnemoen.net>
To:	David Laight <David.Laight@...lab.com>
Cc:	Nicolas Ferre <nicolas.ferre@...el.com>, netdev@...r.kernel.org,
	davem@...emloft.net, bhutchings@...arflare.com,
	linux-arm-kernel@...ts.infradead.org, plagnioj@...osoft.com,
	patrice.vilchez@...el.com, linux-kernel@...r.kernel.org,
	manabian@...il.com
Subject: Re: [PATCH v3 06/10] net/macb: clean up ring buffer logic

On Tue, Oct 30, 2012 at 4:12 AM, David Laight <David.Laight@...lab.com> wrote:
>> Instead of masking head and tail every time we increment them, just let them
>> wrap through UINT_MAX and mask them when subscripting. Add simple accessor
>> functions to do the subscripting properly to minimize the chances of messing
>> this up.
> ...
>> +static unsigned int macb_tx_ring_avail(struct macb *bp)
>> +{
>> +     return TX_RING_SIZE - (bp->tx_head - bp->tx_tail);
>> +}
>
> That one doesn't look quite right to me.
> Surely it should be masking with 'TX_RING_SIZE - 1'

Why is that? head and tail can never be more than TX_RING_SIZE apart,
so it shouldn't make any difference.

Havard
--
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/