Hi! > > Sorry, I'm just not going to apply a patch like that. > > > > I mean, how the heck is anyone else supposed to understand what you're up > > to? > > Hmm, I might just withdraw this patch 1/5. This is generally a slowpath, > and it's hard to guarantee that any exported user doesn't rely on the > full barrier here (not that they would know whether they do or not, let > alone document the fact). > > I think all the others are pretty clear, though? (read on if no) ... > > There's a bit of documentation in Documentation/atomic_ops.txt > > (probably enough, I guess) but it is totally unobvious to 98.3% of kernel > > developers when they should use test_and_set_bit() versus > > test_and_set_bit_lock() and it is far too much work to work out why it was > > used in __wait_on_bit_lock(), whether it is correct, what advantages it > > brings and whether and where others should emulate it. > > If you set a bit for the purpose of opening a critical section, then > you can use this. And clear_bit_unlock to close it. > > The advantages are that it is faster, and the hapless driver writer > doesn't have to butcher or forget about doing the correct > smp_mb__before_clear_bit(), or have reviewers wondering exactly WTF > that barrier is for, etc.
Actually, I'd expect *_lock() ro be slower than *()... > Basically, it is faster, harder to get wrong, and more self-docuemnting. So I'd not call it self-documenting. -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - 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/
