From: Dan Carpenter <dan.carpenter@oracle.com>
To: Paolo Abeni <pabeni@redhat.com>
Cc: Mat Martineau <mathew.j.martineau@linux.intel.com>,
Geliang Tang <geliang.tang@suse.com>,
Matthieu Baerts <matthieu.baerts@tessares.net>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>,
netdev@vger.kernel.org, mptcp@lists.linux.dev,
kernel-janitors@vger.kernel.org
Subject: Re: [PATCH net-next] mptcp: fix deadlock in mptcp_close()
Date: Thu, 5 May 2022 15:23:52 +0300 [thread overview]
Message-ID: <20220505122352.GT4031@kadam> (raw)
In-Reply-To: <0606e0fede42a16c93231498d23c9afd5c05e26e.camel@redhat.com>
On Thu, May 05, 2022 at 01:50:01PM +0200, Paolo Abeni wrote:
> On Thu, 2022-05-05 at 14:03 +0300, Dan Carpenter wrote:
> > The mptcp_data_lock/unlock(sk) functions are taking the same spin lock
> > as the lock_sock()/release_sock() functions. So we're already holding
> > the lock at this point and taking it again will lead to a deadlock.
>
> Note that lock_sock() (and release_sock()) releases the relevant
> spinlock before completion. AFAICs the above deadlock is not possible.
>
Oh. Yeah. You're right. I had hard coded into my local copy of Smatch
that it took that lock.
{"lock_sock_nested", LOCK, spin_lock, 0, "&$->sk_lock.slock"},
{"release_sock", UNLOCK, spin_lock, 0, "&$->sk_lock.slock"},
But that's wrong... It drops the lock as you say.
regards,
dan carpenter
prev parent reply other threads:[~2022-05-05 12:24 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-05 11:03 [PATCH net-next] mptcp: fix deadlock in mptcp_close() Dan Carpenter
2022-05-05 11:50 ` Paolo Abeni
2022-05-05 12:23 ` Dan Carpenter [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=20220505122352.GT4031@kadam \
--to=dan.carpenter@oracle.com \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=geliang.tang@suse.com \
--cc=kernel-janitors@vger.kernel.org \
--cc=kuba@kernel.org \
--cc=mathew.j.martineau@linux.intel.com \
--cc=matthieu.baerts@tessares.net \
--cc=mptcp@lists.linux.dev \
--cc=netdev@vger.kernel.org \
--cc=pabeni@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;
as well as URLs for NNTP newsgroup(s).