From: Johannes Berg <johannes@sipsolutions.net>
To: Ben Greear <greearb@candelatech.com>,
"Valo, Kalle" <kvalo@qca.qualcomm.com>
Cc: "ath10k@lists.infradead.org" <ath10k@lists.infradead.org>,
"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: [PATCH 2/3] ath10k: Grab rcu_read_lock before the txqs spinlock.
Date: Mon, 12 Sep 2016 08:41:49 +0200 [thread overview]
Message-ID: <1473662509.4201.0.camel@sipsolutions.net> (raw)
In-Reply-To: <57D2CB92.3020407@candelatech.com> (sfid-20160909_164754_211937_A51918C3)
> > > - rcu_read_unlock();
> > > spin_unlock_bh(&ar->txqs_lock);
> > > + rcu_read_unlock();
> >
> > I'm no RCU expert but this isn't making any sense. Maybe it changes
> > timings on your kernel so that it hides the real problem?
>
> I'm not sure this fixed anything or not, it just seemed weird so I
> changed it.
>
> I was hoping someone that understood rcu locking would comment...
>
RCU is no "locking". The sooner you get over that notion, the better.
This therefore make no sense whatsoever.
In fact, you want to keep the RCU protected section *small*, so having
the spinlock inside hurts overall system performance.
johannes
next prev parent reply other threads:[~2016-09-12 6:41 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-19 1:26 [PATCH 1/3] ath10k: Ensure there are no stale ar->txqs entries greearb
2016-08-19 1:26 ` [PATCH 2/3] ath10k: Grab rcu_read_lock before the txqs spinlock greearb
2016-08-19 3:01 ` Manoharan, Rajkumar
2016-08-19 3:28 ` Ben Greear
2016-09-09 13:36 ` Valo, Kalle
2016-09-09 14:47 ` Ben Greear
2016-09-12 6:41 ` Johannes Berg [this message]
2016-09-12 16:37 ` Ben Greear
2016-08-19 1:26 ` [PATCH 3/3] ath10k: Improve logging message greearb
2016-08-19 6:35 ` Mohammed Shafi Shajakhan
2016-09-09 13:30 ` Valo, Kalle
2016-09-13 12:29 ` [3/3] " Kalle Valo
2016-08-19 6:59 ` [PATCH 1/3] ath10k: Ensure there are no stale ar->txqs entries Michal Kazior
2016-08-19 13:34 ` Ben Greear
2016-12-01 22:52 ` Ben Greear
2016-12-02 0:24 ` Ben Greear
2016-12-05 8:50 ` Michal Kazior
2016-12-05 18:19 ` Ben Greear
2016-09-09 17:25 ` Felix Fietkau
2016-09-09 17:46 ` Ben Greear
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=1473662509.4201.0.camel@sipsolutions.net \
--to=johannes@sipsolutions.net \
--cc=ath10k@lists.infradead.org \
--cc=greearb@candelatech.com \
--cc=kvalo@qca.qualcomm.com \
--cc=linux-wireless@vger.kernel.org \
/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).