On Tue, Apr 22, 2003 at 10:11:11AM +0200, 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);
> }
>
> Calling the function foo() works proper in none SMP kernels. I assume, the
... only because spinlocks are no-op on UP.
> spinlocks internaly will be initialized as
> recursive semaphore as default. So it is possible to aquire it more than
> once by the same thread.
Spinlocks are *not* recursive. The code above is a bug - it's just that
on non-SMP it doesn't get caught.
Spinlock is a mutex, not a recursive sempahore.
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This archive was generated by hypermail 2b29 : Wed Apr 23 2003 - 22:00:32 EST