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    SubjectRe: [PATCH 4/7] ufs: remove the BKL
    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/)


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