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Message-ID: <a8ea7199230682f3fd53e0b5975afa7287bd5ac0.camel@egluetechnologies.com>
Subject: Re: [PATCH RESEND 0/2] j1939: make sure that sent DAT/CTL frames
 are marked as TX
From:   Devid Antonio Filoni <devid.filoni@egluetechnologies.com>
To:     Oleksij Rempel <o.rempel@pengutronix.de>
Cc:     Robin van der Gracht <robin@protonic.nl>, kernel@pengutronix.de,
        linux-can@vger.kernel.org, Oleksij Rempel <linux@rempel-privat.de>,
        Oliver Hartkopp <socketcan@hartkopp.net>,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Maxime Jayat <maxime.jayat@mobile-devices.fr>,
        kbuild test robot <lkp@intel.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Date:   Tue, 10 May 2022 20:12:32 +0200
In-Reply-To: <20220510043406.GB10669@pengutronix.de>
References: <20220509170746.29893-1-devid.filoni@egluetechnologies.com>
         <20220510043406.GB10669@pengutronix.de>
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Hi Oleksij,

On Tue, 2022-05-10 at 06:34 +0200, Oleksij Rempel wrote:
> Hi Devid,
> 
> On Mon, May 09, 2022 at 07:07:44PM +0200, Devid Antonio Filoni wrote:
> > Hello,
> > 
> > If candump -x is used to dump CAN bus traffic on an interface while a J1939
> > socket is sending multi-packet messages, then the DAT and CTL frames
> > show up as RX instead of TX.
> > 
> > This patch series sets to generated struct sk_buff the owning struct sock
> > pointer so that the MSG_DONTROUTE flag can be set by recv functions.
> > 
> > I'm not sure that j1939_session_skb_get is needed, I think that session->sk
> > could be directly passed as can_skb_set_owner parameter. This patch
> > is based on j1939_simple_txnext function which uses j1939_session_skb_get.
> > I can provide an additional patch to remove the calls to
> > j1939_session_skb_get function if you think they are not needed.
> 
> Thank you for your patches. By testing it I noticed that there is a memory
> leak in current kernel and it seems to be even worse after this patches.
> Found by this test:
> https://github.com/linux-can/can-tests/blob/master/j1939/run_all.sh#L13
> 
> 
> Can you please investigate it (or wait until I get time to do it).
> 
> Regards,
> Oleksij
> 

I checked the test you linked and I can see that the number of the
instances of the can_j1939 module increases on each
j1939_ac_100k_dual_can.sh test execution (then the script exits),
however this doesn't seem to be worse with my patches, I have the same
results with the original kernel. Did you execute a particular test to
verify that the memory leak is worse with my patches?
I tried to take a look at all code that I changed in my patches but the
used ref counters seem to be handled correctly in called functions. I
suspected that the issue may be caused by the ref counter increased
in can_skb_set_owner() function but, even if I remove that call from the
j1939_simple_txnext() function in original kernel, I can still reproduce
the memory leak.
I think the issue is somewhere else, I'll try to give another look but I
can't assure nothing.

Best Regards,
Devid