Messages in this thread |  | | | Date | Tue, 22 Apr 2003 11:25:36 +0200 | | From | Jens Axboe <> | | Subject | Re: inconsistent usage of |
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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
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