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?
