netdev - Re: [PATCH] net: fix softnet

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] [day] [month] [year] [list]

Date:	Thu, 15 Apr 2010 12:22:51 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Tom Herbert <therbert@...gle.com>, netdev@...r.kernel.org
Subject: Re: [PATCH] net: fix softnet_stat

On Thu, Apr 15, 2010 at 12:14 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> Le jeudi 15 avril 2010 à 05:40 +0200, Eric Dumazet a écrit :
>
> Oh well, I revert this comment, we need a mutual exclusion between cpus
> if we dont want to miss some increments, even in a slow path.
>
> __get_cpu_var(netdev_rx_stat).field++; is safe because updated only by
> this cpu.
>
> Once you use per_cpu(netdev_rx_stat, cpu).field++; you need a
> synchronization since this is not atomic.
>

rps_unlock() is a synchronization if needed.

> so queue->dropped++ is safer and faster too (inside the rps_lock
> section)
>

It involves more lines of code, moving netdev_rx_stat into softdata.

-- 
Regards，
Changli Gao(xiaosuo@...il.com)
--
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