Messages in this thread | | | Date | Mon, 21 Oct 2019 19:13:06 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [GIT PULL] SafeSetID LSM changes for 5.4 |
| |
On Mon, Oct 21, 2019 at 08:58:11AM +0200, Ingo Molnar wrote: > > * Paul E. McKenney <paulmck@kernel.org> wrote: > > > --- a/include/linux/rcupdate.h > > +++ b/include/linux/rcupdate.h > > @@ -383,20 +383,22 @@ do { \ > > } while (0) > > > > /** > > - * rcu_swap_protected() - swap an RCU and a regular pointer > > - * @rcu_ptr: RCU pointer > > + * rcu_replace() - replace an RCU pointer, returning its old value > > + * @rcu_ptr: RCU pointer, whose old value is returned > > * @ptr: regular pointer > > - * @c: the conditions under which the dereference will take place > > + * @c: the lockdep conditions under which the dereference will take place > > * > > - * Perform swap(@rcu_ptr, @ptr) where @rcu_ptr is an RCU-annotated pointer and > > - * @c is the argument that is passed to the rcu_dereference_protected() call > > - * used to read that pointer. > > + * Perform a replacement, where @rcu_ptr is an RCU-annotated > > + * pointer and @c is the lockdep argument that is passed to the > > + * rcu_dereference_protected() call used to read that pointer. The old > > + * value of @rcu_ptr is returned, and @rcu_ptr is set to @ptr. > > */ > > -#define rcu_swap_protected(rcu_ptr, ptr, c) do { \ > > +#define rcu_replace(rcu_ptr, ptr, c) \ > > +({ \ > > typeof(ptr) __tmp = rcu_dereference_protected((rcu_ptr), (c)); \ > > rcu_assign_pointer((rcu_ptr), (ptr)); \ > > - (ptr) = __tmp; \ > > -} while (0) > > + __tmp; \ > > +}) > > One small suggestion, would it make sense to name it "rcu_replace_pointer()"? > > This would make it fit into the pointer handling family of RCU functions: > rcu_assign_pointer(), rcu_access_pointer(), RCU_INIT_POINTER() et al?
Easy enough to make the change. I will do that tomorrow and test over the following night.
> rcu_swap() would also look a bit weird if used in MM code. ;-)
How much RCU swap should we configure on this system? About same amount as reader-writer swap! ;-)
Thanx, Paul
| |