Re: [PATCH] LSM networking: skb hooks for 2.5.42 (2/7)

From: Greg KH (gregat_private)
Date: Tue Oct 15 2002 - 12:16:26 PDT

  • Next message: David S. Miller: "Re: [PATCH] LSM networking: skb hooks for 2.5.42 (2/7)"

    On Tue, Oct 15, 2002 at 02:14:01PM -0400, Donald Becker wrote:
    >   - Your method adds a bunch of hooks when just one would do.
    
    How would you propose a single hook?  Specify the action in the hook?
    Linus has already rejected this idea :)
    
    > The usual approach is
    >    if (obj->hookfun)  obj->hookfun(obj, method_index, other_params);
    > 
    > Even this makes the code less readable, but at least doesn't jump all
    > over the instruction space.  The impact is a dereference and a test for
    > zero, and then a jump over a push/mov instructions for values that
    > should already be in registers.
    
    Linus has stated that he didn't want the check and then jump, but an
    unconditional jump (even if the function is nothing but a return.)  I
    guess this is faster as the processor doesn't have to guess at branch
    prediction.  That's why we built these calls in this way.
    
    That being said, a number of people have asked that the networking hooks
    be able to "be compiled away", so we will be glad to do this.
    
    thanks,
    
    greg k-h
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