From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] srcu: API for barrier after srcu read unlock
Date: Wed, 6 Nov 2013 12:00:44 -0800 [thread overview]
Message-ID: <20131106200044.GN18245@linux.vnet.ibm.com> (raw)
In-Reply-To: <527A5985.6050309@cn.fujitsu.com>
On Wed, Nov 06, 2013 at 11:00:21PM +0800, Lai Jiangshan wrote:
> On 11/05/2013 04:55 AM, Paul E. McKenney wrote:
> > On Mon, Nov 04, 2013 at 10:36:17PM +0200, Michael S. Tsirkin wrote:
> >> srcu read lock/unlock include a full memory barrier
> >> but that's an implementation detail.
> >> Add an API for make memory fencing explicit for
> >> users that need this barrier, to make sure we
> >> can change it as needed without breaking all users.
> >>
> >> Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> >> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> >
> > Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
>
> Acked-by: "Lai Jiangshan" <laijs@cn.fujitsu.com>
Very good, queued for 3.14.
Thanx, Paul
> >> ---
> >> include/linux/srcu.h | 14 ++++++++++++++
> >> 1 file changed, 14 insertions(+)
> >>
> >> diff --git a/include/linux/srcu.h b/include/linux/srcu.h
> >> index c114614..9b058ee 100644
> >> --- a/include/linux/srcu.h
> >> +++ b/include/linux/srcu.h
> >> @@ -237,4 +237,18 @@ static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
> >> __srcu_read_unlock(sp, idx);
> >> }
> >>
> >> +/**
> >> + * smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock
> >> + *
> >> + * Converts the preceding srcu_read_unlock into a two-way memory barrier.
> >> + *
> >> + * Call this after srcu_read_unlock, to guarantee that all memory operations
> >> + * that occur after smp_mb__after_srcu_read_unlock will appear to happen after
> >> + * the preceding srcu_read_unlock.
> >> + */
> >> +static inline void smp_mb__after_srcu_read_unlock(void)
> >> +{
> >> + /* __srcu_read_unlock has smp_mb() internally so nothing to do here. */
> >> +}
> >> +
> >> #endif
> >> --
> >> MST
> >>
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at http://www.tux.org/lkml/
> >
>
prev parent reply other threads:[~2013-11-06 20:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-04 20:36 [PATCH 1/2] srcu: API for barrier after srcu read unlock Michael S. Tsirkin
2013-11-04 20:36 ` [PATCH 2/2] kvm: optimize out smp_mb after srcu_read_unlock Michael S. Tsirkin
2013-11-04 20:55 ` [PATCH 1/2] srcu: API for barrier after srcu read unlock Paul E. McKenney
2013-11-06 15:00 ` Lai Jiangshan
2013-11-06 20:00 ` Paul E. McKenney [this message]
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=20131106200044.GN18245@linux.vnet.ibm.com \
--to=paulmck@linux.vnet.ibm.com \
--cc=laijs@cn.fujitsu.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mst@redhat.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