From: Steffen Klassert <steffen.klassert@secunet.com>
To: Shan Wei <shanwei88@gmail.com>
Cc: David Miller <davem@davemloft.net>,
NetDev <netdev@vger.kernel.org>,
Herbert Xu <herbert@gondor.hengli.com.au>,
Kernel-Maillist <linux-kernel@vger.kernel.org>,
cl@linux-foundation.org
Subject: Re: [PATCH v4 3/9] net: xfrm: use __this_cpu_read per-cpu helper
Date: Tue, 13 Nov 2012 08:21:01 +0100 [thread overview]
Message-ID: <20121113072101.GG22290@secunet.com> (raw)
In-Reply-To: <50A1A7C9.3060703@gmail.com>
On Tue, Nov 13, 2012 at 09:52:09AM +0800, Shan Wei wrote:
> From: Shan Wei <davidshan@tencent.com>
>
Please add a proper commit message, explaining why you do this change.
>
> Signed-off-by: Shan Wei <davidshan@tencent.com>
> ---
> v4:
> derefrence pointer before reading to avoid compile warning.
> ---
> net/xfrm/xfrm_ipcomp.c | 8 +++-----
> 1 files changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
> index e5246fb..2906d52 100644
> --- a/net/xfrm/xfrm_ipcomp.c
> +++ b/net/xfrm/xfrm_ipcomp.c
> @@ -276,18 +276,16 @@ static struct crypto_comp * __percpu *ipcomp_alloc_tfms(const char *alg_name)
> struct crypto_comp * __percpu *tfms;
> int cpu;
>
> - /* This can be any valid CPU ID so we don't need locking. */
> - cpu = raw_smp_processor_id();
>
> list_for_each_entry(pos, &ipcomp_tfms_list, list) {
> struct crypto_comp *tfm;
>
> - tfms = pos->tfms;
> - tfm = *per_cpu_ptr(tfms, cpu);
> + /* This can be any valid CPU ID so we don't need locking. */
> + tfm = __this_cpu_read(*pos->tfms);
This should just fetch the tfm pointer, so why exactly __this_cpu_read
is better than __this_cpu_ptr? Please keep in mind that performance is
not the most important thing here. It's much more important that it
works in any case.
next prev parent reply other threads:[~2012-11-13 7:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-13 1:52 [PATCH v4 3/9] net: xfrm: use __this_cpu_read per-cpu helper Shan Wei
2012-11-13 7:21 ` Steffen Klassert [this message]
2012-11-13 9:33 ` Shan Wei
2012-11-13 10:48 ` Steffen Klassert
2012-11-13 12:36 ` [PATCH v5 " Shan Wei
2012-11-14 8:43 ` Steffen Klassert
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20121113072101.GG22290@secunet.com \
--to=steffen.klassert@secunet.com \
--cc=cl@linux-foundation.org \
--cc=davem@davemloft.net \
--cc=herbert@gondor.hengli.com.au \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=shanwei88@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).