diff options
| -rw-r--r-- | include/linux/rcupdate.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 20fb776a1d4a..d5dfb109dfe1 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -922,6 +922,21 @@ void __kfree_rcu(struct rcu_head *head, unsigned long offset) kfree_call_rcu(head, (rcu_callback)offset); } +/* + * Does the specified offset indicate that the corresponding rcu_head + * structure can be handled by kfree_rcu()? + */ +#define __is_kfree_rcu_offset(offset) ((offset) < 4096) + +/* + * Helper macro for kfree_rcu() to prevent argument-expansion eyestrain. + */ +#define __kfree_rcu(head, offset) \ + do { \ + BUILD_BUG_ON(!__is_kfree_rcu_offset(offset)); \ + call_rcu(head, (void (*)(struct rcu_head *))(unsigned long)(offset)); \ + } while (0) + /** * kfree_rcu() - kfree an object after a grace period. * @ptr: pointer to kfree @@ -944,6 +959,9 @@ void __kfree_rcu(struct rcu_head *head, unsigned long offset) * * Note that the allowable offset might decrease in the future, for example, * to allow something like kmem_cache_free_rcu(). + * + * The BUILD_BUG_ON check must not involve any function calls, hence the + * checks are done in macros here. */ #define kfree_rcu(ptr, rcu_head) \ __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head)) |