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SubjectRe: want opinions on possible glitch in 2.4 network error reporting
On Thu, 7 Feb 2002, Alan Cox wrote:

> > there is no way to "lose" that data before it hits the wire, unless of
> > course the network driver is broken and doesn't plug the upper layers when
> > its TX queue is full.
> UDP is not flow controlled.

No, of course not, but this has *nothing* to do with UDP. The IP socket
itself is flow controlled, and so is the TX queue of the network driver.

Let me give you another example: ping -f. If what you said were true, ping -f
would send packets as fast as the CPU can generate into the black hole
called an IP raw socket, right? Well, that just doesn't happen, because
sendto/sendmsg will block until there is enough space in the TX queue of
the raw socket.

I'll state again: if data (UDP or otherwise) is lost after sendto()
returns success but before it hits the wire, something is BROKEN in that
IP stack.


It is better to keep your mouth shut and be thought a fool,
than to open it and remove all doubt.

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