diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/asm-generic/bug.h | 7 | ||||
| -rw-r--r-- | include/linux/rcupdate.h | 20 |
2 files changed, 27 insertions, 0 deletions
diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h index f2d2faf..e5a3f58 100644 --- a/include/asm-generic/bug.h +++ b/include/asm-generic/bug.h @@ -194,6 +194,13 @@ extern void warn_slowpath_null(const char *file, const int line); #ifdef CONFIG_SMP # define WARN_ON_SMP(x) WARN_ON(x) #else +/* + * Use of ({0;}) because WARN_ON_SMP(x) may be used either as + * a stand alone line statement or as a condition in an if () + * statement. + * A simple "0" would cause gcc to give a "statement has no effect" + * warning. + */ # define WARN_ON_SMP(x) ({0;}) #endif diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index af56148..ff422d2 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -339,6 +339,12 @@ extern int rcu_my_thread_group_empty(void); ((typeof(*p) __force __kernel *)(p)); \ }) +#define __rcu_access_index(p, space) \ + ({ \ + typeof(p) _________p1 = ACCESS_ONCE(p); \ + rcu_dereference_sparse(p, space); \ + (_________p1); \ + }) #define __rcu_dereference_index_check(p, c) \ ({ \ typeof(p) _________p1 = ACCESS_ONCE(p); \ @@ -429,6 +435,20 @@ extern int rcu_my_thread_group_empty(void); #define rcu_dereference_raw(p) rcu_dereference_check(p, 1) /*@@@ needed? @@@*/ /** + * rcu_access_index() - fetch RCU index with no dereferencing + * @p: The index to read + * + * Return the value of the specified RCU-protected index, but omit the + * smp_read_barrier_depends() and keep the ACCESS_ONCE(). This is useful + * when the value of this index is accessed, but the index is not + * dereferenced, for example, when testing an RCU-protected index against + * -1. Although rcu_access_index() may also be used in cases where + * update-side locks prevent the value of the index from changing, you + * should instead use rcu_dereference_index_protected() for this use case. + */ +#define rcu_access_index(p) __rcu_access_index((p), __rcu) + +/** * rcu_dereference_index_check() - rcu_dereference for indices with debug checking * @p: The pointer to read, prior to dereferencing * @c: The conditions under which the dereference will take place |
