lkml.org 
[lkml]   [2016]   [Jun]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH tip/core/rcu 07/12] rcu: No ordering for rcu_assign_pointer() of NULL
On Wed, Jun 15, 2016 at 02:46:08PM -0700, Paul E. McKenney wrote:
> This commit does a compile-time check for rcu_assign_pointer() of NULL,
> and uses WRITE_ONCE() rather than smp_store_release() in that case.
>
> Reported-by: Christoph Hellwig <hch@infradead.org>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> ---
> include/linux/rcupdate.h | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
> index c61b6b9506e7..9be61e47badc 100644
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -650,7 +650,16 @@ static inline void rcu_preempt_sleep_check(void)
> * please be careful when making changes to rcu_assign_pointer() and the
> * other macros that it invokes.
> */
> -#define rcu_assign_pointer(p, v) smp_store_release(&p, RCU_INITIALIZER(v))
> +#define rcu_assign_pointer(p, v) \
> +({ \
> + uintptr_t _r_a_p__v = (uintptr_t)(v); \
> + \
> + if (__builtin_constant_p(v) && (_r_a_p__v) == (uintptr_t)NULL) \
> + WRITE_ONCE((p), (typeof(p))(_r_a_p__v)); \
> + else \
> + smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \
> + _r_a_p__v; \
> +})

Can we pretty please right align the '\'s ?

Also, didn't we used to do this and then reverted it again for some
obscure reason?

\
 
 \ /
  Last update: 2016-06-16 00:41    [W:0.127 / U:0.824 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site