From: <[EMAIL PROTECTED]>
> Hello!
>
> > * davem's patch breaks apps that assume that write(,PIPE_BUF) after
> > poll(POLLOUT) never blocks, even for blocking pipes.
>
> Pardon, but PIPE_BUF <= PAGE_SIZE yet, so that fears have no reasons.
>
The difference is the =
> <<<<< davem's patch
> + if (count >= PAGE_SIZE &&
> ^^
> + !(filp->f_flags & O_NONBLOCK)) {
> <<<<<<< my patch
> + if (count > PIPE_BUF && chars == PIPE_SIZE &&
^
> + (!(filp->f_flags & O_NONBLOCK))) {
> <<<<<<<
davem used >=, I used >. All other differences between our patches are
code cleanups.
Just try this on i386: (PIPE_BUF is defined to 4096 on i386 - I really
don't understand why, but now it's too late to reverse it back to 512)
<<<<
char buf[PIPE_BUF];
void main()
{
int pipes[2];
pipe(pipes);
write(pipes[1],buf,sizeof(buf));
}
<<<<<<<
It returns immediately on all unix platforms I tested, including all
linux versions, except with davem's patch.
It's not guaranteed in sus or posix, but I'm reluctant to change it.
--
Manfred
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