Re: [PATCH tip/core/rcu 06/14] rcu: Remove return value from RCU_INIT_POINTER()

Josh Triplett
2012-06-15T20:50:30Z

On Fri, Jun 15, 2012 at 01:13:07PM -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
>
> The return value from RCU_INIT_POINTER() is not used, and using it
> would be quite ugly, for example:
>
> q = RCU_INIT_POINTER(global_p, p);
>
> To prevent this sort of ugliness from appearing, this commit wraps
> RCU_INIT_POINTER() in a do-while loop.
>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

Reviewed-by: Josh Triplett <josh@joshtriplett.org>

> include/linux/rcupdate.h | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
> index eb92c21..f2cca02 100644
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -904,7 +904,9 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
> * the reader-accessible portions of the linked structure.
> */
> #define RCU_INIT_POINTER(p, v) \
> - p = (typeof(*v) __force __rcu *)(v)
> + do { \
> + p = (typeof(*v) __force __rcu *)(v); \
> + } while (0)
>
> /**
> * INIT_RCU_POINTER() - statically initialize an RCU protected pointer
> --
> 1.7.8
>