if computer hangs, sl-modem-daemon looses internet

Bug #47808 reported by towsonu2003 on 2006-06-01
Affects Status Importance Assigned to Milestone
sl-modem (Ubuntu)

Bug Description

Binary package hint: sl-modem-daemon

To replicate:
0. Your modem is a winmodem that has alsa support and works with this daemon.
1. find a way to hang your computer for a very brief time (1 second, may be less)
2. use sl-modem-daemon and wvdial to dial up your ISP
3. make the computer hang
4. Try browsing w. any browser: you don't have network connection anymore, but your computer doesn't know that.
5. Kill wvdial and dial again...

This is an upstream bug for sure bc this happens with the precompiled daemon available from linmodems site. I just couldn't find a way to file this bug to them...

Laurent Bigonville (bigon) wrote :

The daemon should maybe launched with a negative nice value?

towsonu2003 (towsonu2003) wrote :

that would work (as a temporary fix). the higher its priority, the less chance it has to drop the connection... but even with top priority, it drops the connection if the computer hangs long enough.

Bryan Haskins (bryan-h) wrote :

I can completely confirm this, WvDial eventually kills with an error 15.

--> Disconnecting at Sat Nov 11 17:22:24 2006
--> The PPP daemon has died: Lack of LCP echo responses (exit code = 15)
--> man pppd explains pppd error codes in more detail.
--> I guess that's it for now, exiting
--> Provider is overloaded(often the case) or line problem.
--> The PPP daemon has died. (exit code = 15)

Now normally it could just be a crappy ISP posing the issue, but it's too conveniently timed after intensive CPU or disk use. this may also have to do with the slmodem-daemon locking up entirely requiring a few lines of command or a restart.

Basilio Kublik (sourcercito) wrote :

Thank you for taking the time to report this bug and helping to make Ubuntu better. You reported this bug a while ago and there hasn't been any activity in it recently. We were wondering is this still an issue for you? Thanks in advance.

Changed in sl-modem:
status: New → Incomplete
Ian Jackson (ijackson) wrote :

I imagine this problem still persists, although the submitter doesn't say how they cause their computer to hang and the exact behaviour would depend on that.

The problem here is inherent to the hardware: a winmodem is not really a modem at all; it's just an analogue-to-digital converter and it relies on the computer to do all of the hard modem stuff. That modem stuff is very timing critical so if the computer is busy for any reason it breaks.

We run sl-modem-daemon with a very high priority (RTPRIO) and arrange for all of it to be loaded into memory permanently, to try to reduce the occurrence of these problems, but fundamentally the only real solution to this problem is to buy a real modem.

Changed in sl-modem:
status: Incomplete → Invalid
towsonu2003 (towsonu2003) wrote :

if MS can do it, Linux can too. Your solution is not a solution but avoidance - are you trying to artificially reduce the number of open bugs?

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