Re: [PATCH -tip] remove the BKL: Replace BKL in mount/umountsyscalls with a mutex

From: Ingo Molnar
Date: Thu Apr 16 2009 - 12:07:28 EST



* Alessio Igor Bogani <abogani@xxxxxxxxxx> wrote:

> Replace ths BKL in sys_mount()/sys_umount() syscalls with a regular mutex.
>
> Signed-off-by: Alessio Igor Bogani <abogani@xxxxxxxxxx>
> ---
> fs/namespace.c | 16 +++++++++-------
> fs/super.c | 9 ++++-----
> 2 files changed, 13 insertions(+), 12 deletions(-)

Ok, this patch needs to be flamed^W commented on by Al.

Al: this patch is very likely broken as i cannot imagine you leaving
the BKL there just so. So lets accept that (and your NAK) as a given
and not get upset about it too much.

We are willing to fix any side effects and preconditions before this
can be done - and it would be nice if you could donate a few minutes
to this effort by enumerating those preconditions for us, so that we
can provide the real fixes. No-one knows this code better than you
so even if we could guess our way around to a certain degree, some
maintainer guidance and insight would be deeply appreciated.

I'm wondering how much the BKL use here is made necessary by the
sys_open() BKL use in device drivers. Jonathan has done extensive
work on the sys_open front (and there's more such work in
tip:core/kill-the-BKL) - perhaps that has largely paved the way for
this change?

There's also ioctl BKL use - is the BKL use here in sys_mount
necessiated by the (naked) BKL use in those handlers?

Thanks,

Ingo
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