Re: [PATCH] [2.5] Non-blocking write can block

[P. Benie]

On Wed, 4 Jun 2003, Linus Torvalds wrote:

> On Wed, 4 Jun 2003, P. Benie wrote:
> > The problem isn't to do with large writes. It's to do with any sequence of
> > writes that fills up the receive buffer, which is only 4K for N_TTY. If
> > the receiving program is suspended, the buffer will fill sooner or later.
>
> Well, even then we could just drop the "write_atomic" lock.
>
> The thing is, I don't know what the tty atomicity guarantees are. I know
> what they are for pipes (quite reasonable), but tty's?

We don't have a PIPE_BUF-style atomicity guarantee, even though this would
be quite useful. This lock is only used to prevent simultaneous writes
from being interleaved. I've always assumed that when writes shouldn't be
interleaved, but I can't quote a source for that.

Peter