Commit-ID: 331b6d8c7afc2e5b900b9dcd850c265e1ba8d8e7 Gitweb: http://git.kernel.org/tip/331b6d8c7afc2e5b900b9dcd850c265e1ba8d8e7 Author: Peter Zijlstra <[email protected]> AuthorDate: Sun, 22 May 2016 12:48:27 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Wed, 8 Jun 2016 14:22:47 +0200
locking/barriers: Validate lockless_dereference() is used on a pointer type Use the type to validate the argument @p is indeed a pointer type. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Alexey Dobriyan <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Paul McKenney <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- include/linux/compiler.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 793c082..06f27fd 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -545,10 +545,14 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s * Similar to rcu_dereference(), but for situations where the pointed-to * object's lifetime is managed by something other than RCU. That * "something other" might be reference counting or simple immortality. + * + * The seemingly unused void * variable is to validate @p is indeed a pointer + * type. All pointer types silently cast to void *. */ #define lockless_dereference(p) \ ({ \ typeof(p) _________p1 = READ_ONCE(p); \ + __maybe_unused const void * const _________p2 = _________p1; \ smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ (_________p1); \ })
