Messages in this thread | | | Date | Tue, 22 Apr 2003 10:21:38 +0100 | From | viro@parcelfa ... | Subject | Re: inconsistent usage of |
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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. - 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/
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