linux-kernel - [PATCH 1/2] rcu: introduce kfree

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Date:   Fri, 20 Nov 2020 12:49:16 +0100
From:   "Uladzislau Rezki (Sony)" <urezki@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>, RCU <rcu@...r.kernel.org>,
        "Paul E . McKenney" <paulmck@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Neeraj Upadhyay <neeraju@...eaurora.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Michal Hocko <mhocko@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Theodore Y . Ts'o" <tytso@....edu>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Uladzislau Rezki <urezki@...il.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>
Subject: [PATCH 1/2] rcu: introduce kfree_rcu() single argument macro

There is a kvfree_rcu() single argument macro that pairs
with kvmalloc() allocated pointer. Even though it also
deals with SLAB one, it might be confused for the users.

That is why add an extra kfree_rcu() macro that explicitly
pairs with kmalloc() pointer and its name, so it becomes
more obvious for users.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
---
 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 e09c0d87b3c3..b1e75648d402 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -853,8 +853,9 @@ 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(both for single argument and double one)
+ * @rhf: the name of the struct rcu_head within the type of @ptr,
+ *       only for double argument.
  *
  * Many rcu callbacks functions just call kfree() on the base structure.
  * These functions are trivial, but their size adds up, and furthermore
@@ -877,13 +878,7 @@ 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.
@@ -915,7 +910,14 @@ 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);				\
-- 
2.20.1