On Sun, 23 May 2010 07:30:01 +0200 Michael Kerrisk <mtk.manpages@xxxxxxxxx> wrote: > Hi all, > > I see that this patch has hit Linus's git, so some questions > > On Wed, May 19, 2010 at 6:49 PM, Linus Torvalds > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > > > On Wed, 19 May 2010, Miklos Szeredi wrote: > >> > >> One issue I see is that it's possible to grow pipes indefinitely. > >> Should this be restricted to privileged users? > > > > Yes. But perhaps only if it grows past the default (or perhaps "default*2" > > or similar). That way a normal user could shrink the pipe buffers, and > > then grow them again if he wants to. > > > > Oh, and I think you need to also require that there be at least two > > buffers. Otherwise we can't guarantee POSIX behavior, I think. > > Is there any documentation (e.g., a man-pages patch) for these changes? > > The argument of the fcntl() operations is expressed in pages. I take > it that this means that the semantics of the argument will very > depending on the system page size? So for example, 2 on x86 will mean > 8192 bytes, but will mean 32768 of ia64? That seems very weird. (And > what about architectures where the page size is switchable?) Such > changes in semantics should not be silent for the use, IMO. Well, there is getpagesize(). But I agree - this interface is just asking (x86) people to write non-portable code. otoh, if the arg was in bytes, they'd just hard-code "8192". They're clever like that. But we have gone to some lengths to avoid exposing things like PAGE_SIZE and HZ in procfs, so it makes sense to take the same approach to syscalls. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
