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SubjectRe: PATCH: psaux lockups on SMP 2.4.0-test*
Kevin Buhr wrote:

> There's an insidious spinlock hang hidden in "drivers/char/pc_keyb.c".
> "handle_mouse_event" is called with the "kbd_controller_lock" held. If it
> sees an "AUX_RECONNECT" scancode on the wire, it tries to---according
> to the comments---"ping the mouse". Unfortunately, it does this using
> "aux_write_ack" which tries to grab the lock again.
> I triggered this while playing protocol games with a new wheel mouse.
> Presumably, anyone who plugs a PS/2 mouse into a running SMP machine
> will hang their machine; and a flakey mouse that generates spurious
> AUX_RECONNECT messages (or even a working mouse that happens to generate
> that scancode validly) would lead to mysterious lockups, I think.
> Anyway, here's a patch. I've tested this on 2.4.0-test5, but it should
> work fine on test7, too.

Hi all,

I have similar problems with a PS/2 mouse on my machine and 2.4.0-test7.
The mouse works ok under X if gpm is not loaded. When loading gpm -t ps2
(gpm 1.19.3) the mouse doesn't work at all in textmode. After killing
gpm and starting it a second time, the machine freezes. This is 100%
reproduceable. I've tried the patch Kevin Buhr posted but it doesn't
change things.

Machine is: i686 Linux-2.4.0-test7 (vanilla)
It's an uniprocessor machine without SMP support, hence the spinlock
issue above doesn't apply here.

IRQ assignment is as follows:

irq 0: 178330 timer irq 9: 0 acpi
irq 1: 3427 keyboard irq 10: 53381 ide0, ide1
irq 2: 0 cascade [4] irq 11: 23 bttv
irq 5: 29039 eth0 irq 12: 49690 PS/2 Mouse
irq 6: 2 irq 13: 1 fpu
irq 7: 1 parport0 [3] irq 14: 708 ide2
irq 8: 1 rtc irq 15: 93661

I seem to remember that the mouse worked with earlier 2.4.0-testX
versions, but I can't exactly tell at which point things broke.


Udo Steinberg.
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