On Fri, May 04, 2007 at 11:24:33AM -0700, Don Fry wrote:
> All instances of obtaining the lock in pcnet32 are done as
> spin_lock_irqsave except the interrupt handler itself. The interrupt mask
> needs to be saved everywhere else, but the interrupt handler is known not
> to need to save the flags.
>
> If the lock is held and the same CPU tries to get the lock again, it will
> wait a very long time ;-(. I believe the locking is fine for a
> non-preemptable kernel, but I have little experience with a preemptable
> kernel.
>
> When does a preemptable kernel allow interrupts to occur?
I have no idea actually.
> Is there a bug in this particular architectures locking code?
On i386? I hope not.
> From looking at preempt-locking.txt the driver has (1) no per-cpu data,
> (2) 'CPU state protection' should be fine,
> (3) the 'lock is acquired and released by the same task'.
> I don't see a problem unless I am misunderstanding something.
Well I don't know, but something is going wrong and causing the soft
lock up. I must admit I am surprised if an interrupt can occour while
handling an interrupt, but then again maybe that is supposed to be
allowed.
--
Len Sorensen
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