Re: SMP system panic with down/up calls for locking. Need help on

B. James Phillippe (bryan@terran.org)
Mon, 4 Oct 1999 15:28:59 -0700 (PDT)


On Mon, 4 Oct 1999, WANG,YIDING (HP-SanJose,ex1) wrote:

> Under SMP (8 CPUs) system with 2.2.5-15smp kernel, when adding down()/up()
> pair for critical section locking purpose in my fibre channel driver (to
> system, it is scsi), system panic. Acutually even under UP system,

1.) you can't call down() at interrupt time, as it is basically going to
put the caller to sleep/schedule() if the count goes below 0. Sleeping at
interrupt-time is not allowed. You're almost certainly using this at
interrupt-time context, right? I'm not certain exactly what kind of
locking you need, but investigate spinlocks:
linux/Documentation/spinlocks.txt

2.) 2.2.5-15smp is not a kernel version, but a particular packaging of a
particular kernel version by a particular vendor. You should really be
downloading and working with the latest kernels "by-hand" if you're going
to do development. This way you won't be chasing bugs that have already
been fixed, and you won't be relying on faith in someone elses idea of a
valid kernel configuration.

-bp

--
# bryan at terran dot org
# http://www.terran.org/~bryan

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