From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: jarkao2@gmail.com, netdev@vger.kernel.org
Subject: Re: [PATCH] pkt_sched: Fix lockdep warning on est_tree_lock in gen_estimator
Date: Thu, 02 Sep 2010 13:59:29 -0700 (PDT) [thread overview]
Message-ID: <20100902.135929.15241881.davem@davemloft.net> (raw)
In-Reply-To: <1283460813.3699.243.camel@edumazet-laptop>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 02 Sep 2010 22:53:33 +0200
> Maybe after a night, I'll understand ?
>
> est_tree_lock is only taken by process context, and I dont see what can
> be the problem. Are you sure its not a lockdep false positive, or that
> the real bug is elsewhere ?
>
> Sure, we can block BH everywhere, it will reduce bugs and lockdep
> alarms, but I would like to understand before, why its needed.
>
> If you believe est_tree_lock can be taken by a softirq handler, please
> tell me ;)
Hint: est->stats_lock is actually a pointer to a qdisc->lock
Therefore we must comply with the rules of qdisc locking if we wish
to take est->stats_lock in conjunction with est_tree_lock.
The strange mention of qdisc_tx_lock changing state inside of
est_timer() in the lockdep warning should have been the clue :-)
next prev parent reply other threads:[~2010-09-02 20:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-02 20:12 [PATCH] pkt_sched: Fix lockdep warning on est_tree_lock in gen_estimator Jarek Poplawski
2010-09-02 20:22 ` David Miller
2010-09-02 20:32 ` Eric Dumazet
2010-09-02 20:55 ` Jarek Poplawski
2010-09-03 5:26 ` Eric Dumazet
2010-09-02 20:53 ` Eric Dumazet
2010-09-02 20:59 ` David Miller [this message]
2010-09-02 21:22 ` Jarek Poplawski
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=20100902.135929.15241881.davem@davemloft.net \
--to=davem@davemloft.net \
--cc=eric.dumazet@gmail.com \
--cc=jarkao2@gmail.com \
--cc=netdev@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).