Re: [PATCH 0/4] cifs: fix oopses and mem corruption with concurrent mount/umount (try #4)

[Steve French]

On Thu, Oct 30, 2008 at 12:42 PM, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> I think we want to resist having locks that protect too many things.
> With that, we end up with the locks held over too much code. Not only is
> that generally worse for performance, but it can paper over race
> conditions.

I agree that it is trivially worse for performance to have a single
spinlock protecting the three interrelated structures (cifs tcp, smb
and tree connection structs), but since they point to one another and
frequently have operations that require us to use all three lists -
to do things like iterate through all tree connections within a
particular smb session, or iterate across all cifs smb sessions within
each cifs tcp session - it makes code more complicated to have to grab
and unlock multiple spinlocks in the correct order every time across
all exit paths etc.



-- 
Thanks,

Steve
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