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    SubjectRe: [PATCH] Export symbol ksize()
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    Hi Johannes,

    On Mon, 2009-02-16 at 14:56 +0100, Johannes Weiner wrote:
    > On Tue, Feb 10, 2009 at 04:06:53PM +0200, Pekka J Enberg wrote:
    > > On Tue, Feb 10, 2009 at 03:35:03PM +0200, Pekka Enberg wrote:
    > > > > We unexported ksize() because it's a problematic interface and you
    > > > > almost certainly want to use the alternatives (e.g. krealloc). I think
    > > > > I need bit more convincing to apply this patch...
    > >
    > > On Tue, 10 Feb 2009, Kirill A. Shutemov wrote:
    > > > It just a quick fix. If anybody knows better solution, I have no
    > > > objections.
    > >
    > > Herbert, what do you think of this (untested) patch? Alternatively, we
    > > could do something like kfree_secure() but it seems overkill for this one
    > > call-site.
    >
    > There are more callsites which do memset() + kfree():
    >
    > arch/s390/crypto/prng.c
    > drivers/s390/crypto/zcrypt_pcixcc.c
    > drivers/md/dm-crypt.c
    > drivers/usb/host/hwa-hc.c
    > drivers/usb/wusbcore/cbaf.c
    > (drivers/w1/w1{,_int}.c)
    > fs/cifs/misc.c
    > fs/cifs/connect.c
    > fs/ecryptfs/keystore.c
    > fs/ecryptfs/messaging.c
    > net/atm/mpoa_caches.c
    >
    > How about the attached patch? One problem is that zeroing ksize()
    > bytes can have an overhead of nearly twice the actual allocation size.
    >
    > So we would need an interface that lets the caller pass in either a
    > number of bytes it wants to have zeroed out or say idontknow.
    >
    > Perhaps add a size parameter that is cut to ksize() if it's too big?
    > Or (ssize_t)-1 for figureitoutyourself?

    I'd prefer the kzfree() interface as-is. I don't think you want to do
    the memset/kfree in a fast-path anyway.

    If you can convince Andrew to pick this patch up and maybe convert some
    call-sites to actually use it, then:

    Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

    Pekka



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