Re: [PATCH] drivers/char/vt possible race
From: Benjamin Herrenschmidt
Date: Tue Feb 10 2004 - 00:29:44 EST
On Tue, 2004-02-10 at 15:34, Andrew Morton wrote:
> Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> wrote:
> >
> > Hi !
> >
> > I falled again on the crash in con_do_write() with driver->data
> > beeing NULL. It happens during boot, when userland is playing
> > open/close games with tty's, I was intentionally typing keys like
> > mad during boot trying to trigger another problem when this one
> > poped up.
>
> OK. Was this patch confirmed to prevent any reoccurrences?
Well, I didn't see it again, and if for some reason, we still
enter the function with tty->driver_data == NULL (which may still
happen if the tty layer itself isn't serializing, which I suspect),
we will print a warning and bail out.
In the end, I suppose the warning can be removed, but I want to
make sure that if the race still happens, we behave properly now.
The patch makes sure the vt internal state stays consistent.
> > Andrew: I suggest putting that in -mm for a while, and if it
> > doesn't trigger any new problem, upstream, maybe without my
> > 2 printk's "argh" :)
>
> Yup. I'll also bring back the sysfs patch which somehow triggers
> this race.
Yup, let me know.
Ben.
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