Re: [bug] WARNING: at drivers/char/tty_io.c:1266tty_open+0x1ea/0x388()

From: Ingo Molnar
Date: Tue Jun 16 2009 - 15:43:57 EST

* Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:

> > I'm wondering, how long have these patches been in linux-next?
> > Has no-one reported an easy (or easier) reproducer than a plain
> > bootup (which really doesnt hit the tty code intentionally
> > hard)?
> Quite a while - and the open side stuff hasn't changed in the post
> 2.6.30 patches at all. Your box seems to show stuff up that most
> users just don't hit.

Another box has triggered that too btw. But with your two fixes:

69e8fd4: tty: fix sanity check
9f7a9ce: ldisc: Make sure the ldisc isn't active when we close it

i havent seen any new tty warnings today. (testing is a bit spotty
due to other bugs though - this is typical of the merge window.)

Also, the only warning that remained after your fix was the new
warning you added to catch an old bug - that's not a regression

> > You should probably also write testcases and stress-tests if you
> > modify code in this area.
> I did - they hang the tty layers in 2.6.30 and earlier in about 60
> seconds, it then corrupts the module counts and dies shortly
> after. I've not published them because they can obviously be
> seriously misused.

Too bad - i could have ran them in the test mix.

> I don't have the luxury of building on solid foundations trying to
> sort the tty layer out - its been broken since 2.1.x when the
> lock_kernel logic stopped applying to IRQ handlers.

No complaints from me at all! You are doing fantastic cleanups and
fixes in the TTY code.

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