Re: [Bug report] dvbv5-zap crash dvb-tool ARMHF builds

[Samuel CHEMLA <chemla.samuel@xxxxxxxxx>]

On 01/04/2019 20:58, Samuel CHEMLA wrote:
> Le jeu. 28 mars 2019 à 20:18, Mauro Carvalho Chehab
> <mchehab+samsung@xxxxxxxxxx> a écrit :
> > Em Thu, 28 Mar 2019 19:48:35 +0100
> > Samuel CHEMLA <chemla.samuel@xxxxxxxxx> escreveu:
> >
> > > Hi,
> > Please, don't top post.
> > > 1) I did reproduce the bug with a serial console, but the serial
> > > console was also frozen, and there was no message before freeze.
> > The only way for a machine to freeze even on serial console is due to
> > a very serious Kernel or hardware bug, like a bad lock/semaphore.
> >
> > > 2) I also tried a powered USB HUB but it didn't change anything.
> > Ok.
> >
> > > 3) I tried DVBJet, from https://github.com/lightful/DVBdirect , it is
> > > a tuner that directly does ioctl on linux kernel DVB device.
> > > I couldn't reproduce the issue with DVBJet.
> > I don't know DVBJet. If it uses the same Kernel drivers, maybe
> > it could then be a race issue: send commands on a slower way to
> > the Kernel would be solving the issue.
> >
> > > It's been running for almost 48Hrs now, without a crash.
> > > I collect all PIDs on the multiplex, just like dvbv5-zap, so the USB
> > > port is solicited at it's maximum.
> > >
> > > That makes me think it is not a hardware issue.
> > > I'm pretty sure dvbv5-zap can still improve, and it already did when
> > > you fixed: struct arguments args = {};
> > Everything can be improved, but the thing is that we need first to
> > discover the root cause :-)
> >
> > Can you post on pastebin (or equivalent) the dmesg with the
> > DVBJet running? Maybe it could be printing some Kernel messages
> > that might help to discover what's going wrong.
> Here is the dmesg: https://pastebin.com/3XRim4XL
> Just look at the code, it's quite straightforward, just a few ioctl.
>
> > Btw, could you also apply this patch:
> >          https://patchwork.linuxtv.org/patch/55274/
> OK, I'll give it a try and provide feedback

I tested you patch against 4.14.98 which is the current raspbian kernel, 
but it didn't change anything...

> > It is probably unrelated, but this is the kind of bug that could cause
> > such issues.
> >
> > > Regards
> > >
> > > Le mar. 26 mars 2019 à 16:31, Mauro Carvalho Chehab
> > > <mchehab+samsung@xxxxxxxxxx> a écrit :
> > > > Em Tue, 26 Mar 2019 16:10:33 +0100
> > > > Samuel CHEMLA <chemla.samuel@xxxxxxxxx> escreveu:
> > > >
> > > > > Hi,
> > > > >
> > > > >
> > > > > > Earlier you said "random hangs are back". When this happens, does the whole
> > > > > > device become unresponsive or just dvbv5-zap?
> > > > > The device completely freeze, you can't even switch numlock on/off.
> > > > dvbv5-tools can't hang the machine. this is very likely happening due to
> > > > a Kernel crash.
> > > >
> > > > > I said "the issue is back", it is because I **thought** it was gone.
> > > > > To be more precise:
> > > > > - on raspberry zero W, the issue is gone since Mauro's patch
> > > > > (https://git.linuxtv.org/v4l-utils.git/commit/?id=22b06353227e04695b1b0a9622b896b948adba89)
> > > > > - on raspberry 2, the issue, it is still there and the patch has no
> > > > > effect (the issue was and is still there)
> > > > RPi2 has a serious issue with their USB ports: on devices that require
> > > > more than a few mW to work, it causes several device disconnection and
> > > > re-connection, as it cannot sustain the required 5V.
> > > >
> > > > Depending on how fast this happens, it could be triggering some Kernel
> > > > bug.
> > > >
> > > > That affects most V4L and DVB devices. You should either use a powered
> > > > USB 2.0 hub (with may be problematic, as the USB host driver on RPi
> > > > has issues - and may cause data loss on high sustained ISOC traffic,
> > > > specially when used with hubs) or a device that has its own power
> > > > supply, like DVBSky T680C or S960.
> > > >
> > > > > > Since this issue is "back",
> > > > > > I wouldn't be surprised this is unrelated to the fixes in 1.12.7 and 1.16.4.
> > > > > The issue doesn't appear anymore on raspberry zero W since Mauro's commit.
> > > > > So it did improve on that platform.
> > > > >
> > > > > > It would be useful to see the output from dmesg (best thing would be after
> > > > > > the issue occurs).
> > > > > You can't, device is frozen.
> > > > > Logs are not flushed to disk, and journalctl -f freeze before showing anything
> > > > You can use a serial port in order to get the logs. On a serial console,
> > > > use something like:
> > > >
> > > >          # dmesg -n 8
> > > >
> > > > In order to make sure it will display all Kernel messages at console.
> > > >
> > > > > > Also what dvb hardware are you using?
> > > > > I reproduced it with different two tuners: rtl2832U from RTL-SDR.COM
> > > > > and a TerraTec Cinergy T Stick+
> > > > None of them supports an external power supply.
> > > >
> > > > > You can found all the details here:
> > > > > https://bugs.launchpad.net/raspbian/+bug/1819650
> > > > >
> > > > >
> > > > > Sam
> > > > >
> > > > >
> > > > > Le mar. 26 mars 2019 à 14:26, Sean Young <sean@xxxxxxxx> a écrit :
> > > > > > Hi Sam,
> > > > > >
> > > > > > On Tue, Mar 26, 2019 at 08:35:44AM +0100, Samuel CHEMLA wrote:
> > > > > > > Hi,
> > > > > > >
> > > > > > >
> > > > > > > I am struggling with valgrind because it always complain with either :
> > > > > > >      ASan runtime does not come first in initial library list; you
> > > > > > > should either link runtime to your application or manually preload it
> > > > > > > with LD_PRELOAD
> > > > > > >      -> When I LD_PRELOAD, I'm getting a segfault, but I couldn't find
> > > > > > > any core dump
> > > > > > >
> > > > > > > or, if I link statically libasan with -static-libasan:
> > > > > > >      Shadow memory range interleaves with an existing memory mapping.
> > > > > > > ASan cannot proceed correctly. ABORTING.
> > > > > > >      ASan shadow was supposed to be located in the
> > > > > > > [0x00007fff7000-0x10007fff7fff] range.
> > > > > > >
> > > > > > >
> > > > > > > I retested again on my raspberry zero W, and I confirm i cannot
> > > > > > > reproduce the hang.
> > > > > > > Your fix did work on that device.
> > > > > > > I am testing with same OS (raspbian with latest updates, same kernel),
> > > > > > > same configure options, same USB dongle... :-(
> > > > > > > The only differences are CPU architecture (armv6 vs armv7), memory
> > > > > > > constraints, and I was not using the same channels.conf, I'll fix that
> > > > > > > today and re-check
> > > > > > Earlier you said "random hangs are back". When this happens, does the whole
> > > > > > device become unresponsive or just dvbv5-zap? Since this issue is "back",
> > > > > > I wouldn't be surprised this is unrelated to the fixes in 1.12.7 and 1.16.4.
> > > > > >
> > > > > > It would be useful to see the output from dmesg (best thing would be after
> > > > > > the issue occurs).
> > > > > >
> > > > > > Also what dvb hardware are you using?
> > > > > >
> > > > > > Thanks,
> > > > > >
> > > > > > san
> > > > > >
> > > > > > > Sam
> > > > > > >
> > > > > > > On 25/03/2019 18:08, Mauro Carvalho Chehab wrote:
> > > > > > >
> > > > > > > Em Mon, 25 Mar 2019 17:33:30 +0100
> > > > > > > Samuel CHEMLA <chemla.samuel@xxxxxxxxx> escreveu:
> > > > > > >
> > > > > > > Hi guys,
> > > > > > >
> > > > > > > I'm afraid I'm coming with sad news.
> > > > > > > I just tried both stable-1.12 and stable-1.16 on a raspberry pi 2, and
> > > > > > > random hangs are back (see https://bugs.launchpad.net/raspbian/+bug/1819650
> > > > > > > ).
> > > > > > > I previously test both branches on a raspberry zero and issues were gone
> > > > > > > (same raspbian version).
> > > > > > > There may be more memory issues somewhere...
> > > > > > >
> > > > > > > Could you test it with valgrind?
> > > > > > >
> > > > > > > Sam
> > > > > > >
> > > > > > > Le jeu. 21 mars 2019 ŕ 20:59, Gregor Jasny <gjasny@xxxxxxxxxxxxxx> a écrit :
> > > > > > >
> > > > > > > Hello,
> > > > > > >
> > > > > > > On 21.03.19 12:30, Mauro Carvalho Chehab wrote:
> > > > > > >
> > > > > > > I went ahead and cherry-picked the relevant patches to -1.12, -1.14 and
> > > > > > > -1.16, and tested both dvbv5-zap and dvbv5-scan with all versions. So,
> > > > > > >
> > > > > > > we can
> > > > > > >
> > > > > > > release a new minor version for all those stable branches.
> > > > > > >
> > > > > > > After the patches, on my tests, I didn't get any memory leaks or
> > > > > > > double-free issues.
> > > > > > >
> > > > > > > I issues a new 1.12, 1.14, and 1.16 release.
> > > > > > >
> > > > > > > Thanks,
> > > > > > > Gregor
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > Thanks,
> > > > > > > Mauro
> > > >
> > > >
> > > > Thanks,
> > > > Mauro
> >
> >
> > Thanks,
> > Mauro