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SubjectRe: [PATCH 2.4] sys_select() return error on bad file


On Thu, 4 Mar 2004, Armin Schindler wrote:

> On Thu, 4 Mar 2004, Willy Tarreau wrote:
> > Hi,
> >
> > On Wed, Mar 03, 2004 at 09:46:54AM +0100, Armin Schindler wrote:
> > > --- linux/fs/select.c_orig 2004-03-02 19:06:44.000000000 +0100
> > > +++ linux/fs/select.c 2004-03-03 09:25:24.000000000 +0100
> > > @@ -183,6 +183,8 @@
> > > wait = NULL;
> > > retval = 0;
> > > for (;;) {
> > > + int file_err = 1;
> > > +
> >
> > Just a thought, select() is often performance-critical, and adding one more
> > variable inside the loop can slow it down a bit. Wouldn't it be cheaper to
> > set retval to -EBADF above and avoid using file_err ?
>
> retval cannot be used for that, it may get changed in the loop.
>
> Anyway, I don't see how your proposal would do better performance?
> My patch just adds a new variable on the stack, which should not make any
> difference in performance. And later, it is the same if the new or another
> variable gets changed or checked.

Curiosity: Does SuS/POSIX define behaviour for "all fds are closed" ?


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