Messages in this thread |  | | From | Roger Larsson <> | Date | Sat, 25 Nov 2000 19:58:15 +0100 | Subject | Re: *_trylock return on success? |
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On Saturday 25 November 2000 18:49, Rik van Riel wrote: > On Sat, 25 Nov 2000, Roger Larsson wrote: > > Questions: > > What are _trylocks supposed to return? > > It depends on the type of _trylock ;( > > > Does spin_trylock and down_trylock behave differently? > > Why isn't the expected return value documented? > > The whole trylock stuff is, IMHO, a big mess. When you > change from one type of trylock to another, you may be > forced to invert the logic of your code since the return > code from the different locks is different. > > For bitflags, for example, the trylock returns the state > the bit had before the lock (ie. 1 if the thing was already > locked). >
This holds for down_trylocks too. It looks like it is the spinlocks that are wrong... :-(
As most return values tend to be error returns that also matches other code in functionallity.
> > For spinlocks, it'll probably return something else ;/ It does...
I guess fixing this is too much too late?
It looks like ppc mixes the ways... from arch/ppc/lib/locks.c:46
int spin_trylock(spinlock_t *lock) { if (__spin_trylock(&lock->lock)) /* one on failure */ return 0; /* zero on failure */ lock->owner_cpu = smp_processor_id(); lock->owner_pc = (unsigned long)__builtin_return_address(0); return 1; }
BUT anyway... The thing I hit is not a bug in the kernel proper - it is in the preemptive stuff.
/RogerL
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