linux-kernel - Re: [PATCH 4/9] net: openvswitch: use this_cpu

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: <0000013ab7e86f8a-4adb8b81-19be-4264-96f1-924aaf3819f2-000000@email.amazonses.com>
Date:	Wed, 31 Oct 2012 17:39:54 +0000
From:	Christoph Lameter <cl@...ux.com>
To:	Shan Wei <shanwei88@...il.com>
cc:	jesse@...ira.com, dev@...nvswitch.org,
	NetDev <netdev@...r.kernel.org>,
	Kernel-Maillist <linux-kernel@...r.kernel.org>,
	David Miller <davem@...emloft.net>
Subject: Re: [PATCH 4/9] net: openvswitch: use this_cpu_ptr per-cpu helper

On Wed, 31 Oct 2012, Shan Wei wrote:

> --- a/net/openvswitch/datapath.c
> +++ b/net/openvswitch/datapath.c
> @@ -208,7 +208,7 @@ void ovs_dp_process_received_packet(struct vport *p, struct sk_buff *skb)
>  	int error;
>  	int key_len;
>
> -	stats = per_cpu_ptr(dp->stats_percpu, smp_processor_id());
> +	stats = this_cpu_ptr(dp->stats_percpu);

Well this is an improvement and may be ok if the preemption is disabled at
this point. There is another possibility here to use this_cpu_read/add/inc
instead of determining the pointer to the local cpu first and then
performing operations on the fields. The pointer relocation with
this_cpu_xxx ops is implicit in the instructions and safe against changing
of processors. It would also save us the determination of a pointer to the
current cpus stats structure.

--
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/