On Mon, Feb 11, 2008 at 04:59:54PM -0800, Stephen Hemminger wrote:
> Eliminate warnings when rcu_assign_pointer is used with unsigned long.
> It is reasonable to use RCU with non-pointer values so allow it for general
> use.  Add a comment to explain the if test.

Good catch!!!  (An apologies for the hassle!!!)

Acked-by: Paul E. McKenney <[EMAIL PROTECTED]>

> Signed-off-by: Stephen Hemminger <[EMAIL PROTECTED]>
> ---
>  include/linux/rcupdate.h |   13 +++++++------
>  1 files changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
> index 37a642c..c44ac87 100644
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -172,14 +172,15 @@ struct rcu_head {
>   * structure after the pointer assignment.  More importantly, this
>   * call documents which pointers will be dereferenced by RCU read-side
>   * code.
> + *
> + * If value is the NULL (constant 0), then no barrier is needed.
>   */
> 
> -#define rcu_assign_pointer(p, v) \
> -     ({ \
> -             if (!__builtin_constant_p(v) || \
> -                 ((v) != NULL)) \
> -                     smp_wmb(); \
> -             (p) = (v); \
> +#define rcu_assign_pointer(p, v)                     \
> +     ({                                              \
> +             if (!(__builtin_constant_p(v) && v))    \
> +                     smp_wmb();                      \
> +             (p) = (v);                              \
>       })
> 
>  /**
> -- 
> 1.5.3.8
> 
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