Re: [PATCH 4/7] ufs: remove the BKL

[Nick Bowler]

On 2011-03-02 00:13 +0100, Arnd Bergmann wrote:
> This introduces a new per-superblock mutex in UFS to replace
> the big kernel lock. I have been careful to avoid nested
> calls to lock_ufs and to get the lock order right with
> respect to other mutexes, in particular lock_super.
> 
> I did not make any attempt to prove that the big kernel
> lock is not needed in a particular place in the code,
> which is very possible.
> 
> The code is still only compile-tested,

This isn't true anymore; I've been running with this patch (well, the
previous versions thereof) for some time now.  On the other hand, I
don't use all of this driver's features.

> but it should at least be harmless on non-SMP systems, since the new
> mutex is not taken on those.

I think this part of the patch is strange.  It seems like a gratuitous
difference between SMP/preempt and other systems to #if out the code
that takes the mutex.  This might make problems with the conversion fly
under the radar longer because people with older systems won't encounter
them.

-- 
Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)
--
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/