sio interrupt-level buffer overflows

[Oleg Tarasov]

Hello,

Bruce Evans <bde at zeta.org.au> wrote:

> I can't explain the panic.  The only relevant difference that I can think
> of is that the change gives larger interrupt-level buffers in sio.  ppp
> might be depending on them not being very large.  However, at the interrupt
> level, ppp just copies data 1 character at a time into mbufs, so there is
> not much to go wrong.  Does the panic occur in ppp (in the kernel) or in sio?

This problem had unusual solution. It seems the key to this problem is
that FreeBSD 5.3-STABLE-p5 (I have updated my system) has DEADLOCKS
when intensively using sio device on high speed (115200) with SMP support.
It seems that MPSAFE causes those deadlocks. Turning

debug.mpsafenet="0"

in /boot/loader.conf
makes the system to work fine & stable instead of panicing every hour
or more often

This change works both with original or modified sio.c.
I am grateful for solution with interrupt-level buffer overflows (the
change worked fine, no more overflows) but here we have another, more
serious BUG.

-- 
Best regards,
 Oleg Tarasov                          mailto:subscriber at osk.com.ua