On Mon, 5 Feb 2007, Linus Torvalds wrote: > Indeed. One word is *exactly* what a normal system call returns too. > > That said, normally we have a user-space library layer to turn that into > the "errno + return value" thing, and in the case of async() calls we > very basically wouldn't have that. So either: > > - we'd need to do it in the kernel (which is actually nasty, since > different system calls have slightly different semantics - some don't > return any error value at all, and negative numbers are real numbers) > > - we'd have to teach user space about the "negative errno" mechanism, in > which case one word really is alwats enough. > > Quite frankly, I much prefer the second alternative. The "negative errno" > thing has not only worked really really well inside the kernel, it's so > obviously 100% superior to the standard UNIX "-1 + errno" approach that > it's not even funny.
Currently it's in the syscall wrapper. Couldn't we have it in the asys_teardown_stack() stub? > HOWEVER, they get returned differently. The cookie gets returned > immediately, the system call result gets returned in-memory only after the > async thing has actually completed. > > I would actually argue that it's not the kernel that should generate any > cookie, but that user-space should *pass*in* the cookie it wants to, and > the kernel should consider it a pointer to a 64-bit entity which is the > return code. Yes. Let's have the userspace to "mark" the async operation. IMO the cookie should be something transparent to the kernel. Like you said though, that'd require compat-code (unless we fix the size). - Davide - 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/
