On Tue, Apr 22 2003, Heiko.Rabe@InVision.de wrote:
> I found inconsistent behavoir between SMP oand none SMP kernels using spin
> locks inside driver programming
> As first an simple example:
>
> static spinlock_t qtlock = SPIN_LOCK_UNLOCKED;
>
> void foo()
> {
> unsigned long local_flags;
> spin_lock_irqsave (&qtlock, local_flags);
> spin_lock_irqsave (&qtlock, local_flags);
> }
[snip rant]
Check the spinlock implementation. All the above does in UP is
disable/save interrupts twice. The actual spinlock is a nop. As only one
processor can be executing inside the kernel in UP, you only need to
guard against interrupts.
-- Jens Axboe- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Wed Apr 23 2003 - 22:00:32 EST