Re: Should O_NONBLOCK be copied from listening socket to accepting socket?
Chris Evans <[EMAIL PROTECTED]> wrote:
> Well, in our own manpages
> man 7 socket
>It is possible to do non-blocking IO on sockets by setting
>the O_NONBLOCK flag on a socket file descriptor using
>fcntl(2). O_NONBLOCK is inherited through an accept.
Although accept(2) states the opposite:
original socket s is unaffected by this call. Note that
any per file descriptor flags (everything that can be set
with the F_SETFL fcntl, like non blocking or async state)
are not inherited across a accept.
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Re: Should O_NONBLOCK be copied from listening socket to accepting socket?
David S. Miller wrote: > Alexey tried to do this "fix" and when I tested his change we spotted > this issue and thus did not put the "fix" in what we sent to Linus. Is this patch available somewhere on the net? I really need it. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: Should O_NONBLOCK be copied from listening socket to accepting socket?
Chris Evans [EMAIL PROTECTED] wrote:
Well, in our own manpages
man 7 socket
It is possible to do non-blocking IO on sockets by setting
the O_NONBLOCK flag on a socket file descriptor using
fcntl(2). O_NONBLOCK is inherited through an accept.
Although accept(2) states the opposite:
original socket s is unaffected by this call. Note that
any per file descriptor flags (everything that can be set
with the F_SETFL fcntl, like non blocking or async state)
are not inherited across a accept.
--
Debian GNU/Linux 2.2 is out! ( http://www.debian.org/ )
Email: Herbert Xu ~{PmVHI~} [EMAIL PROTECTED]
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
Please read the FAQ at http://www.tux.org/lkml/
Re: Should O_NONBLOCK be copied from listening socket to accepting socket?
From: Michael Shields <[EMAIL PROTECTED]> Date:04 Sep 2000 20:27:53 + Is it required that the O_NONBLOCK flag be copied from a listening socket to an accepted socket? Dan Bernstein believes this is a bug. If we "fixed" this every inetd on every Linux system would unfortunately stop working. So we have to remain bug compatible. Alexey tried to do this "fix" and when I tested his change we spotted this issue and thus did not put the "fix" in what we sent to Linus. Later, David S. Miller [EMAIL PROTECTED] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Re: Should O_NONBLOCK be copied from listening socket to accepting socket?
> Is it required that the O_NONBLOCK flag be copied from a listening > socket to an accepted socket? Dan Bernstein believes this is a bug. My posix 1003.1g draft leaves it undefined. It is possible that SuS clarifies this. Unless he can cite a SuS version that has clarified this I believe its like the SIGIO case - inheritance is platform specific. On the other hand we don't inherit CLOSEONEXEC so why should we inherit NDELAY ? Alan - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
Should O_NONBLOCK be copied from listening socket to accepting socket?
Is it required that the O_NONBLOCK flag be copied from a listening
socket to an accepted socket? Dan Bernstein believes this is a bug.
Pavel Kankovsky writes:
> What happens when x->tcpstate == 1 (i.e. waiting for the first byte of TCP
> request length), x->io->revents == 0 (i.e. not ready for i/o), and
> !taia_less(stamp, >timeout) (i.e. the timeout has expired)?
What happens on working kernels is that the read() returns -1/35,
because that descriptor is nonblocking. For example, under OpenBSD:
% time telnet 127.0.0.1 53
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
Connection closed by foreign host.
0.0u 0.0s 0:10.02 0.0% 0+0k 0+3io 0pf+0w
Apparently Linux 2.2 fails to copy O_NONBLOCK from the listening socket
to the accepted socket, so the same test will block dnscache after 10
seconds; you'll have to close the connection manually. I'd appreciate
hearing exactly which kernel versions have this bug.
Obvious workaround #1: add
if (ndelay_on(x->tcp) == -1) { close(x->tcp); return; } /* Linux bug */
two lines after the accept4() in dnscache.c. Obvious workaround #2: use
a system with the BSD networking stack. (Can't beat the Real Thing.)
Thanks to Pavel for tracking this down. No thanks to Ray for giving us a
bogus diagnosis instead of the crucial logs.
---Dan
--
Shields.
Should O_NONBLOCK be copied from listening socket to accepting socket?
Is it required that the O_NONBLOCK flag be copied from a listening
socket to an accepted socket? Dan Bernstein believes this is a bug.
Pavel Kankovsky writes:
What happens when x-tcpstate == 1 (i.e. waiting for the first byte of TCP
request length), x-io-revents == 0 (i.e. not ready for i/o), and
!taia_less(stamp, x-timeout) (i.e. the timeout has expired)?
What happens on working kernels is that the read() returns -1/35,
because that descriptor is nonblocking. For example, under OpenBSD:
% time telnet 127.0.0.1 53
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
Connection closed by foreign host.
0.0u 0.0s 0:10.02 0.0% 0+0k 0+3io 0pf+0w
Apparently Linux 2.2 fails to copy O_NONBLOCK from the listening socket
to the accepted socket, so the same test will block dnscache after 10
seconds; you'll have to close the connection manually. I'd appreciate
hearing exactly which kernel versions have this bug.
Obvious workaround #1: add
if (ndelay_on(x-tcp) == -1) { close(x-tcp); return; } /* Linux bug */
two lines after the accept4() in dnscache.c. Obvious workaround #2: use
a system with the BSD networking stack. (Can't beat the Real Thing.)
Thanks to Pavel for tracking this down. No thanks to Ray for giving us a
bogus diagnosis instead of the crucial logs.
---Dan
--
Shields.
Re: Should O_NONBLOCK be copied from listening socket to accepting socket?
From: Michael Shields [EMAIL PROTECTED] Date:04 Sep 2000 20:27:53 + Is it required that the O_NONBLOCK flag be copied from a listening socket to an accepted socket? Dan Bernstein believes this is a bug. If we "fixed" this every inetd on every Linux system would unfortunately stop working. So we have to remain bug compatible. Alexey tried to do this "fix" and when I tested his change we spotted this issue and thus did not put the "fix" in what we sent to Linus. Later, David S. Miller [EMAIL PROTECTED] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] Please read the FAQ at http://www.tux.org/lkml/
