linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Lino Sanfilippo <LinoSanfilippo@gmx.de>
To: Pavel Machek <pavel@ucw.cz>
Cc: bh74.an@samsung.com, ks.giri@samsung.com,
	vipul.pandya@samsung.com, peppe.cavallaro@st.com,
	alexandre.torgue@st.com, davem@davemloft.net,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH 2/2] net: ethernet: stmmac: remove private tx queue lock
Date: Wed, 7 Dec 2016 22:43:10 +0100	[thread overview]
Message-ID: <cc10a750-b8ef-a600-4cd5-5b51904c5253@gmx.de> (raw)
In-Reply-To: <20161207213757.GC2250@amd>

Hi Pavel,

On 07.12.2016 22:37, Pavel Machek wrote:
> On Wed 2016-12-07 21:05:38, Lino Sanfilippo wrote:
>> The driver uses a private lock for synchronization between the xmit
>> function and the xmit completion handler, but since the NETIF_F_LLTX flag
>> is not set, the xmit function is also called with the xmit_lock held.
>> 
>> On the other hand the xmit completion handler first takes the private lock
>> and (in case that the tx queue has been stopped) the xmit_lock, leading to
>> a reverse locking order and the potential danger of a deadlock.
>> 
>> Fix this by removing the private lock completely and synchronizing the xmit
>> function and completion handler solely by means of the xmit_lock. By doing
>> this remove also the now unnecessary double check for a stopped tx queue.
>> 
> 
> FYI, here's modified version. I believe _bh versions are needed, and
> I'm testing that version now. (Oh and I also ported it to net-next).
> 
> It survived 30 minutes of testing so far...
> 

First off, thanks for testing.
Hmm. I dont understand why _bh would be needed. We call that function from
BH context only (napi poll and timer).
Any idea?

Lino

  reply	other threads:[~2016-12-07 21:43 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-07 20:05 Remove private locks to avoid possible deadlock Lino Sanfilippo
2016-12-07 20:05 ` [PATCH 1/2] net: ethernet: sxgbe: remove private tx queue lock Lino Sanfilippo
2016-12-07 23:15   ` Francois Romieu
2016-12-08 20:32     ` Lino Sanfilippo
2016-12-08 21:54       ` Pavel Machek
2016-12-08 22:12         ` Lino Sanfilippo
2016-12-08 22:18           ` Pavel Machek
2016-12-08 22:45             ` Lino Sanfilippo
2016-12-08 23:19       ` Francois Romieu
2016-12-09 11:21         ` Pavel Machek
2016-12-10  2:25           ` Lino Sanfilippo
2016-12-11 20:11             ` Pavel Machek
2016-12-15 19:27               ` Lino Sanfilippo
2016-12-15 21:03                 ` Pavel Machek
2016-12-15 21:32                   ` Lino Sanfilippo
2016-12-15 22:33                     ` Lino Sanfilippo
2016-12-17 17:31                       ` Pavel Machek
2016-12-18  0:15                         ` Francois Romieu
2016-12-18 16:15                           ` Lino Sanfilippo
2016-12-18 17:23                             ` Pavel Machek
2016-12-18 18:30                             ` Pavel Machek
2016-12-19 22:49                               ` Lino Sanfilippo
2016-12-18 20:16                             ` Pavel Machek
2016-12-19 10:02                           ` Pavel Machek
2016-12-20  0:05                             ` Francois Romieu
2016-12-07 20:05 ` [PATCH 2/2] net: ethernet: stmmac: " Lino Sanfilippo
2016-12-07 20:55   ` Pavel Machek
2016-12-07 20:59   ` Pavel Machek
2016-12-07 21:37   ` Pavel Machek
2016-12-07 21:43     ` Lino Sanfilippo [this message]
2016-12-07 22:34       ` Lino Sanfilippo
2016-12-07 23:21         ` Pavel Machek
2016-12-07 23:41     ` David Miller
2016-12-08 14:08       ` Pavel Machek
2016-12-08 15:26         ` David Miller
2016-12-08 15:46           ` Pavel Machek

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=cc10a750-b8ef-a600-4cd5-5b51904c5253@gmx.de \
    --to=linosanfilippo@gmx.de \
    --cc=alexandre.torgue@st.com \
    --cc=bh74.an@samsung.com \
    --cc=davem@davemloft.net \
    --cc=ks.giri@samsung.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=pavel@ucw.cz \
    --cc=peppe.cavallaro@st.com \
    --cc=vipul.pandya@samsung.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).