Re: [Bug #14388] keyboard under X with 2.6.31

Linus Torvalds
2009-10-14T01:12:12Z

On Tue, 13 Oct 2009, Frédéric L. W. Meunier wrote:
>
> For now (more than 3h), it isn't doing any harm. And no keyboard lockups.

I think it was Boyan who said he could trigger it "easily", and everybody
else had a hard time to reproduce the problem, so I'll consider your "good
for 3h" to not really be a confirmation either way. But at least it's not
totally broken.

> BTW, the old version of the patch was funny. It booted, but at the login
> prompt I could only enter the first letter.

Yeah, each time somebody read from a tty, the reading would also get rid
of all the buffers, but would leave buf.tail set to the last one (that had
been freed).

Which then resulted in all subsequent IO going to that tail buffer, but
nobody ever seeing it, because 'head' was NULL, and would stay that way as
long as 'tail' existed (which it would until the tty was flushed, which it
would never be).

So you'd only ever see the first read (which could obviously be more than
one character, but you'd have to type REALLY FAST to get there ;^)

Linus