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

david-gFPdbfVZQbY
2009-10-14T01:20:37Z

On Tue, 13 Oct 2009, Linus Torvalds wrote:

> On Tue, 13 Oct 2009, Fr?d?ric 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 ;^)

Interesting, I had a hadful of times in the last several months where I
ran into something like this, but switching virtual terminals cleared it
up.

David Lang