Re: [Bug #14015] pty regressed again, breaking expect and gcc'stestsuite

From: Linus Torvalds
Date: Fri Sep 04 2009 - 13:56:01 EST

On Fri, 4 Sep 2009, Linus Torvalds wrote:
> How about something like this? It's way too anal - it says that we can
> only write data if there's enough space to always push it all the way to
> the receive buffer (including all the data that was already buffered up,
> ie the "memory_used" part). But if it finally makes the problem go away,
> we have another clue.

I forgot to actually include the patch. Duh.

And again - UNTESTED. Maybe this makes the buffering _too_ small (the
'memory_used' thing is not really counted in bytes buffered, it's counted
in how much buffer space we've allocated) and things break even worse and
pty's don't work at all. But I think it might work.


drivers/char/pty.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index d083c73..139fa5a 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -91,7 +91,7 @@ static void pty_unthrottle(struct tty_struct *tty)

static int pty_space(struct tty_struct *to)
- int n = 8192 - to->buf.memory_used;
+ int n = to->receive_room - to->buf.memory_used;
if (n < 0)
return 0;
return n;
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