Messages in this thread | | | Date | Tue, 02 Jan 2001 23:05:01 +0100 | From | Daniel Phillips <> | Subject | Re: [PATCH] move xchg/cmpxchg to atomic.h |
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Roman Zippel wrote: > > On Tue, 2 Jan 2001, David S. Miller wrote: > > > We really can't. We _only_ have load-and-zero. And it has to be > > 16-byte aligned. xchg() is just not something the CPU implements. > > > > Oh bugger... you do have real problems. > > For 2.5 we could move all the atomic functions from atomic.h, bitops.h, > system.h and give them a common interface. We could also give them a new > argument atomic_spinlock_t, which is a normal spinlock, but only used on > architectures which need it, everyone else can "optimize" it away. I think > one such lock per major subsystem should be enough, as the lock is only > held for a very short time, so contentation should be no problem. > Anyway, this had the huge advantage that we could use the complete 32/64 > bit of the atomic value, e.g. for pointer operations.
*Yes*, and I could write: waiters = xchg(&bdflush_waiters.counter, 0);
instead of: waiters = atomic_read(&bdflush_waiters); atomic_sub(waiters, &bdflush_waiters);
in my daemon wakeup patch.
-- Daniel - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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