[tip: core/rcu] rcu: Introduce 2 arg kvfree_rcu() interface

[tip-bot2 for Uladzislau Rezki (Sony)]

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     ce4dce123fdcb5f209752d13f9f06926be65fc78
Gitweb:        https://git.kernel.org/tip/ce4dce123fdcb5f209752d13f9f06926be65fc78
Author:        Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
AuthorDate:    Mon, 25 May 2020 23:47:57 +02:00
Committer:     Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Mon, 29 Jun 2020 11:59:25 -07:00

rcu: Introduce 2 arg kvfree_rcu() interface

kvmalloc() can allocate two types of objects: SLAB backed
and vmalloc backed. How it behaves depends on requested
object's size and memory pressure.

Add a kvfree_rcu() interface that can free memory allocated
via kvmalloc(). It is a simple alias to kfree_rcu() which
can now handle either type of object.

<snip>
    struct test_kvfree_rcu {
        struct rcu_head rcu;
        unsigned char array[100];
    };

    struct test_kvfree_rcu *p;

    p = kvmalloc(10 * PAGE_SIZE);
    if (p)
        kvfree_rcu(p, rcu);
<snip>

Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
Co-developed-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Reviewed-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 include/linux/rcupdate.h |  9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index b344fc8..51b26ab 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -875,6 +875,15 @@ do {									\
 		__kvfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \
 } while (0)
 
+/**
+ * kvfree_rcu() - kvfree an object after a grace period.
+ * @ptr:	pointer to kvfree
+ * @rhf:	the name of the struct rcu_head within the type of @ptr.
+ *
+ * Same as kfree_rcu(), just simple alias.
+ */
+#define kvfree_rcu(ptr, rhf) kfree_rcu(ptr, rhf)
+
 /*
  * Place this after a lock-acquisition primitive to guarantee that
  * an UNLOCK+LOCK pair acts as a full barrier.  This guarantee applies