On Tue, 2007-07-24 at 11:13 -0700, Linus Torvalds wrote: > > On Tue, 24 Jul 2007, Trond Myklebust wrote: > > > > That's not what the Documentation/memory-barriers.txt states: > > Hmm.. You're right. We only actually need it for the unconditional bitops, > like the *unlock* side. > > IOW, if you do a spinlock with the bitops, the locking side should be able > to use a "test_and_set_bit()" on its own, but the unlocking side should be > > smp_mb__before_clear_bit(); > clear_bit(); > > because the ones that don't return a value also don't imply a memory > barrier.
Yup, and this is exactly what we currently do in bit_spin_unlock(). Trond - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
