linux-kernel - [PATCH v2 13/16] rcu: Introduce 2 arg kvfree

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Message-Id: <20200525214800.93072-14-urezki@gmail.com>
Date:   Mon, 25 May 2020 23:47:57 +0200
From:   "Uladzislau Rezki (Sony)" <urezki@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        "Theodore Y . Ts'o" <tytso@....edu>,
        Matthew Wilcox <willy@...radead.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        RCU <rcu@...r.kernel.org>, Uladzislau Rezki <urezki@...il.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>
Subject: [PATCH v2 13/16] 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@...il.com>
Co-developed-by: Joel Fernandes (Google) <joel@...lfernandes.org>
Reviewed-by: Joel Fernandes (Google) <joel@...lfernandes.org>
Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
---
 include/linux/rcupdate.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index b344fc800a9b..51b26ab02878 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
-- 
2.20.1