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

[Mauro Carvalho Chehab <mchehab+samsung@kernel.org>]

Em Tue, 26 Mar 2019 16:10:33 +0100
Samuel CHEMLA <chemla.samuel@gmail.com> 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@mess.org> 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@gmail.com> 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@googlemail.com> 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