modprobe speakupmain hangs

modprobe speakupmain hangs

[Hynek Hanke]

Hello,

we are experiencing a problem with the speakupmain module (the latest
CVS versions with 2.6.18 kernel) on at least one machine here in
Brailcom. I can't say much about it except for this:

1) Our target configuration is Speakup with the sftsyn module. We tried
to load the modules separately and we are sure the hang happens because
of the speakupmain module.

2) The modprobe hangs every time we try to do
	modprobe speakupmain
and when it hangs, the /dev/sftsyn device is still not intialized.

3) After we killall modprobe, the /dev/sftsyn device appears and there
comes a notice about it in syslog. The module stays loaded. It is then
possible to load speakup_sftsyn and Speakup works just fine. I'm not
sure if something is not missing in /proc/speakup or somewhere, but we
didn't notice anything strange.

4) Trying to increase modprobe verbosity or kernel logging level reveals
no additional information. gdb shows that the hang happens inside the
module_init() function in modprobe.

Our workaround is (which also illustrates the issue):
	modprobe speakupmain &
	sleep 1
	killall modprobe
	sleep 1
	modprobe speakup_sftsyn

We would appreciate some help with this or some guidance about how could
we get more information about it. Also, does someone else experience
this issue?

Thanks a lot,
Hynek Hanke

Re: modprobe speakupmain hangs

[luke]

I reported this problem 3 or 4 weeks ago.  Gregory Nowak was able to 
confirm that it was happening.

I was not able to get speakup running after the fact as you describe, 
although I can't say for certain that I tried that exact method.
Greg did not report getting it to work after the fact either.

I solved it by simply having speakup main compile as builtin, instead of 
as a module.

While this is untested in regards to modprobe, it would be better to use:

kill -9 $!

Than it is to use:

killall modprobe

because if any concurrent modprobes happened to be running at that time, 
you could get yourself into some trouble.

Regards,

Luke

On Wed, 1 Nov 2006, Hynek Hanke wrote:

> 
> Hello,
> 
> we are experiencing a problem with the speakupmain module (the latest
> CVS versions with 2.6.18 kernel) on at least one machine here in
> Brailcom. I can't say much about it except for this:
> 
> 1) Our target configuration is Speakup with the sftsyn module. We tried
> to load the modules separately and we are sure the hang happens because
> of the speakupmain module.
> 
> 2) The modprobe hangs every time we try to do
> 	modprobe speakupmain
> and when it hangs, the /dev/sftsyn device is still not intialized.
> 
> 3) After we killall modprobe, the /dev/sftsyn device appears and there
> comes a notice about it in syslog. The module stays loaded. It is then
> possible to load speakup_sftsyn and Speakup works just fine. I'm not
> sure if something is not missing in /proc/speakup or somewhere, but we
> didn't notice anything strange.
> 
> 4) Trying to increase modprobe verbosity or kernel logging level reveals
> no additional information. gdb shows that the hang happens inside the
> module_init() function in modprobe.
> 
> Our workaround is (which also illustrates the issue):
> 	modprobe speakupmain &
> 	sleep 1
> 	killall modprobe
> 	sleep 1
> 	modprobe speakup_sftsyn
> 
> We would appreciate some help with this or some guidance about how could
> we get more information about it. Also, does someone else experience
> this issue?
> 
> Thanks a lot,
> Hynek Hanke

Re: modprobe speakupmain hangs

[Gregory Nowak]

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Hash: SHA1

I've always had speakup_main built into the kernel, so I can't confirm
anything on that. However, I did report a while back having issues
when switching between combinations of none/bns/dtlk/sftsyn on one of
my machines. At the time, since the machine was running an outdated
version of slackware, I theorized that the problem may have to do with
an older version of gcc. Since then however, I've installed debian
testing on this box, and the version of gcc hasn't made a difference
as far as this speakup issue is concerned. Yes, I did build binaries
of the kernel and modules from scratch after upgrading from slackware
to debian.

Greg


On Wed, Nov 01, 2006 at 04:53:59PM -0600, luke wrote:
> I reported this problem 3 or 4 weeks ago.  Gregory Nowak was able to 
> confirm that it was happening.
> 
> I was not able to get speakup running after the fact as you describe, 
> although I can't say for certain that I tried that exact method.
> Greg did not report getting it to work after the fact either.
> 
> I solved it by simply having speakup main compile as builtin, instead of 
> as a module.
> 
> While this is untested in regards to modprobe, it would be better to use:
> 
> kill -9 $!
> 
> Than it is to use:
> 
> killall modprobe
> 
> because if any concurrent modprobes happened to be running at that time, 
> you could get yourself into some trouble.
> 
> Regards,
> 
> Luke
> 

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Re: modprobe speakupmain hangs

[Hynek Hanke]

luke píše v St 01. 11. 2006 v 16:53 -0600:
> I reported this problem 3 or 4 weeks ago.  Gregory Nowak was able to 
> confirm that it was happening.

In that case, I'm sorry for the duplicity.

> While this is untested in regards to modprobe, it would be better to use:
> kill -9 $!

Yes, you are completely right that the quick hack I sent has possible
side effects. Actually, it is pretty broken with the sleeps and all :)
However, I think the method you described is not guaranteed to work,
because in the time of the crash, modprobe is running a child process
and you would risk that this child process ends up being a zombie and
block the thing. I didn't test the exact behavior, but I wouldn't rely
on it. I agree that in other cases what you propose would be a much
cleaner solution.

With regards,
Hynek Hanke

Re: modprobe speakupmain hangs

[luke]

On Thu, 2 Nov 2006, Hynek Hanke wrote:

> However, I think the method you described is not guaranteed to work, 
> because in the time of the crash, modprobe is running a child process 
> and you would risk that this child process ends up being a zombie and 
> block the thing. I didn't test the exact behavior, but I wouldn't rely 
> on it. I agree that in other cases what you propose would be a much 
> cleaner solution.

Well, I did say that it wasn't tested with modprobe.:)

Luke

Re: modprobe speakupmain hangs

[luke]

On Wed, 1 Nov 2006, Gregory Nowak wrote:

> I've always had speakup_main built into the kernel, so I can't confirm
> anything on that. However, I did report a while back having issues

Sorry, my bad.  Greg did *not* say he was having the same problem as was 
I, with speakup_main compiled as a module.  I had recalled it incorrectly.  
In particular, he responded to the post in which I reported the 
speakup_main problem, with a different but similar problem, which I 
misremembered as the same one I was having.  See:

<http://speech.braille.uwo.ca/pipermail/speakup/2006-October/040388.html>

Apologies.

Luke