Re: [PATCH 1/1] Char: vt, make sysfs operations atomic

[Andrew Morton]

On Tue, 27 May 2008 16:48:58 -0400
Aristeu Rozanski <aris@xxxxxxxxx> wrote:

> >> the reason for the code be the way it is is because vcs_{add,remove}_sysfs()
> >> may sleep
> >
> > What's the point? To have races in the code but not sleep inside the semaphore?
> what about fixing the code to remove the race _and_ not sleep inside the
> semaphore? :)
> 

The patch does fix a race, by extending console_sem coverage to provide
exclusion between the sysfs creation and teardown operations.

I assume - no race was identified in the changelog.  Can we actually
simultaneously run con_open() and con_close() against the same device? 
I guess it might be possible if userspace tried hard enough.

I renamed the patch to the much more accurate "vt: hold console_sem
across sysfs operations" - "atomic" in the kernel context means "cannot
context switch" and nothing "atomic" is happening in this patch.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/