On Sun, 4 Jan 2009 10:33:34 -0800 (PST) Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > On Sun, 4 Jan 2009, Arjan van de Ven wrote: > > + > > +typedef u64 async_cookie_t; > > +typedef void (async_func_ptr) (void *data, async_cookie_t cookie); > > + > > +extern void async_schedule(async_func_ptr *ptr, void *data); > > +extern void async_synchronize_full(void); > > +extern void async_synchronize_cookie(async_cookie_t cookie); > > Hmm. The cookie use doesn't seem to make much sense. > > Why do you pass in the cookie to the async function, but don't return > it to the caller? That seems backwards - you'd normally expect that > it is the _caller_ that wants the cookie (to synchronise with a > specific async call), not the callee. But now the only one who knows > the cookie is the wrong entry - just the callee, not the caller. in fact, either could need it. the callee could need it when IT does a global registration (for example to get a device number) at the end of its sequence. We'd want that registration to happen sequential (it's basically the equivalent of a commit/retirement of the instruction in a CPU) the caller could need it when it wants to wait for the async function it kicked off. so both make total sense to me. > > Yes, yes, I read the explanation in the comments, and it says that > the callee should do it to guarantee its own ordering, and your acpi > port thing does that in order to apparently start a sequence that is > asynchronous only wrt the synchronous code, but not wrt itself. > That's a _very_ odd model, but whatever works. But wouldn't it still > make sense to let the caller wait for individual events too? > > IOW, I'd just suggest changing the interface so that > "async_schedule()" also returns the cookie. I had that originally... (as I described in the first mail).. but had no users of it in the places I converted. I'm happy to just return it; it does make sense (that's why I did this originally).... -- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
