On Thu, Jun 16, 2016 at 12:03:39AM +0200, Peter Zijlstra wrote: > 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 <[email protected]> > > Signed-off-by: Paul E. McKenney <[email protected]> > > --- > > 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?
lkml.kernel.org/r/[email protected] What changed since then? And can we now pretty please get rid of that RCU_INIT_POINTER() nonsense?
