[PATCH tip/core/rcu 2/3] rcu: Introduce kfree_rcu() single-argument macro

From: paulmck
Date: Tue Jan 05 2021 - 20:02:09 EST


From: "Uladzislau Rezki (Sony)" <urezki@xxxxxxxxx>

There is a kvfree_rcu() single argument macro that handles pointers
returned by kvmalloc(). Even though it also handles pointer returned by
kmalloc(), readability suffers.

This commit therefore updates the kfree_rcu() macro to explicitly pair
with kmalloc(), thus improving readability.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
include/linux/rcupdate.h | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index de08264..b95373e 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -851,8 +851,9 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)

/**
* kfree_rcu() - kfree an object after a grace period.
- * @ptr: pointer to kfree
- * @rhf: the name of the struct rcu_head within the type of @ptr.
+ * @ptr: pointer to kfree for both single- and double-argument invocations.
+ * @rhf: the name of the struct rcu_head within the type of @ptr,
+ * but only for double-argument invocations.
*
* Many rcu callbacks functions just call kfree() on the base structure.
* These functions are trivial, but their size adds up, and furthermore
@@ -875,13 +876,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
* The BUILD_BUG_ON check must not involve any function calls, hence the
* checks are done in macros here.
*/
-#define kfree_rcu(ptr, rhf) \
-do { \
- typeof (ptr) ___p = (ptr); \
- \
- if (___p) \
- __kvfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \
-} while (0)
+#define kfree_rcu kvfree_rcu

/**
* kvfree_rcu() - kvfree an object after a grace period.
@@ -913,7 +908,14 @@ do { \
kvfree_rcu_arg_2, kvfree_rcu_arg_1)(__VA_ARGS__)

#define KVFREE_GET_MACRO(_1, _2, NAME, ...) NAME
-#define kvfree_rcu_arg_2(ptr, rhf) kfree_rcu(ptr, rhf)
+#define kvfree_rcu_arg_2(ptr, rhf) \
+do { \
+ typeof (ptr) ___p = (ptr); \
+ \
+ if (___p) \
+ __kvfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \
+} while (0)
+
#define kvfree_rcu_arg_1(ptr) \
do { \
typeof(ptr) ___p = (ptr); \
--
2.9.5