rcu: Refactor kvfree_call_rcu() and high-level helpers

Currently a kvfree_call_rcu() takes an offset within a structure as
a second parameter, so a helper such as a kvfree_rcu_arg_2() has to
convert rcu_head and a freed ptr to an offset in order to pass it. That
leads to an extra conversion on macro entry.

Instead of converting, refactor the code in way that a pointer that has
to be freed is passed directly to the kvfree_call_rcu().

This patch does not make any functional change and is transparent to
all kvfree_rcu() users.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

3 files changed, 9 insertions, 10 deletions

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 03abf883a281..f38d4469d7f3 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -1011,8 +1011,7 @@ do {									\
 									\
 	if (___p) {									\
 		BUILD_BUG_ON(!__is_kvfree_rcu_offset(offsetof(typeof(*(ptr)), rhf)));	\
-		kvfree_call_rcu(&((___p)->rhf), (rcu_callback_t)(unsigned long)		\
-			(offsetof(typeof(*(ptr)), rhf)));				\
+		kvfree_call_rcu(&((___p)->rhf), (void *) (___p));			\
 	}										\
 } while (0)
 
@@ -1021,7 +1020,7 @@ do {								\
 	typeof(ptr) ___p = (ptr);				\
 								\
 	if (___p)						\
-		kvfree_call_rcu(NULL, (rcu_callback_t) (___p));	\
+		kvfree_call_rcu(NULL, (void *) (___p));		\
 } while (0)
 
 /*
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 68f9070aa111..7f17acf29dda 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -98,25 +98,25 @@ static inline void synchronize_rcu_expedited(void)
  */
 extern void kvfree(const void *addr);
 
-static inline void __kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
+static inline void __kvfree_call_rcu(struct rcu_head *head, void *ptr)
 {
 	if (head) {
-		call_rcu(head, func);
+		call_rcu(head, (rcu_callback_t) ((void *) head - ptr));
 		return;
 	}
 
 	// kvfree_rcu(one_arg) call.
 	might_sleep();
 	synchronize_rcu();
-	kvfree((void *) func);
+	kvfree(ptr);
 }
 
 #ifdef CONFIG_KASAN_GENERIC
-void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
+void kvfree_call_rcu(struct rcu_head *head, void *ptr);
 #else
-static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
+static inline void kvfree_call_rcu(struct rcu_head *head, void *ptr)
 {
-	__kvfree_call_rcu(head, func);
+	__kvfree_call_rcu(head, ptr);
 }
 #endif
 
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 4003bf6cfa1c..56bccb5a8fde 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -33,7 +33,7 @@ static inline void rcu_virt_note_context_switch(void)
 }
 
 void synchronize_rcu_expedited(void);
-void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
+void kvfree_call_rcu(struct rcu_head *head, void *ptr);
 
 void rcu_barrier(void);
 bool rcu_eqs_special_set(int cpu);