Re: [GIT PULL] SafeSetID LSM changes for 5.4
From: Ingo Molnar <mingo@kernel.org>
Date: 2019-10-21 06:58:18
Also in:
lkml
* Paul E. McKenney [off-list ref] wrote:
quoted hunk ↗ jump to hunk
--- 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? rcu_swap() would also look a bit weird if used in MM code. ;-) Thanks, Ingo