Re: [PATCH] kthread conversion: convert ieee1394 from kernel_thread

From: Stefan Richter
Date: Sun Jun 18 2006 - 06:28:58 EST


I wrote:
I will try to rework this patch

While doing so I discovered an old bug which happens with current code as well as with Linux 2.6.16.x and 2.6.15.x, maybe also on older kernels:

When "modprobe ohci1394" is followed shortly by "modprobe -r ohci1394" (say, 1 second after the previous modprobe finished), one of the following may happen:
- kernel panic due to exception in interrupt
(happened on 2.6.15.x preempt uniprocessor)
or
- modprobe -r hangs in D state, as does knodemgrd_0
(happened on 2.6.16.x preempt SMP on a uniprocessor machine).

I have two FireWirew host adapters installed. The knodemgrd_1 slept interruptibly (S state) while the other slept uninterruptibly (D state) right after modprobe -r was issued. This happens with or without other nodes attached to the FireWire ports. Host adapters are based on a TI 1394b chip (host 0) and on a VIA 1394a chip (host 1).

"All's right with the world" if a longer pause is put between modprobe and modprobe -r, say 4 seconds.

(I will add a bugzilla entry and try to resolve this eventually...)
--
Stefan Richter
-=====-=-==- -==- =--=-
http://arcgraph.de/sr/
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