Hello, Paul.
On Tue, Jun 25, 2013 at 03:57:59PM -0700, Paul E. McKenney wrote:
> > #define list_first_or_null_rcu(ptr, type, member) \
> > ({struct list_head *__ptr = (ptr); \
> > - struct list_head __rcu *__next = list_next_rcu(__ptr); \
> > - likely(__ptr != __next) ? container_of(__next, type, member) : NULL; \
> > + struct list_head *__next = __ptr->next; \
> > + likely(__ptr != __next) ? \
> > + list_entry_rcu(__next, type, member) : NULL; \
>
> I am a bit uneasy with this, and would feel better if the volatile
> cast was on the very first fetch of the ->next pointer.
>
> Is there some reason why my unease is ill-founded?
Do you mean something like the following?
struct list_head *__next = ACCESS_ONCE(__ptr->next); \
likely(__ptr != __next) ? \
list_entry_rcu(__next, type, member) : NULL; \
Yeah, that looks right to me.
Thanks.
--
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
