linux-kernel - [PATCH 1/3] 9p: Drop kref usage

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Date:   Sun,  3 Jul 2022 21:42:41 -0400
From:   Kent Overstreet <kent.overstreet@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     v9fs-developer@...ts.sourceforge.net,
        Kent Overstreet <kent.overstreet@...il.com>,
        Eric Van Hensbergen <ericvh@...il.com>,
        Latchesar Ionkov <lucho@...kov.net>,
        Dominique Martinet <asmadeus@...ewreck.org>
Subject: [PATCH 1/3] 9p: Drop kref usage

This series has only been lightly tested, but it seems to do the trick... how's
it look to you? Commit messages could be better, but I'm not familiar with the
right 9p terminology for some things.

-- >8 --

An upcoming patch is going to require passing the client through
p9_req_put() -> p9_req_free(), but that's awkward with the kref
indirection - so this patch switches to using refcount_t directly.

Signed-off-by: Kent Overstreet <kent.overstreet@...il.com>
Cc: Eric Van Hensbergen <ericvh@...il.com>
Cc: Latchesar Ionkov <lucho@...kov.net>
Cc: Dominique Martinet <asmadeus@...ewreck.org>
---
 include/net/9p/client.h |  6 +++---
 net/9p/client.c         | 19 ++++++++-----------
 2 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/include/net/9p/client.h b/include/net/9p/client.h
index ec1d1706f4..c038c2d73d 100644
--- a/include/net/9p/client.h
+++ b/include/net/9p/client.h
@@ -76,7 +76,7 @@ enum p9_req_status_t {
 struct p9_req_t {
 	int status;
 	int t_err;
-	struct kref refcount;
+	refcount_t refcount;
 	wait_queue_head_t wq;
 	struct p9_fcall tc;
 	struct p9_fcall rc;
@@ -227,12 +227,12 @@ struct p9_req_t *p9_tag_lookup(struct p9_client *c, u16 tag);
 
 static inline void p9_req_get(struct p9_req_t *r)
 {
-	kref_get(&r->refcount);
+	refcount_inc(&r->refcount);
 }
 
 static inline int p9_req_try_get(struct p9_req_t *r)
 {
-	return kref_get_unless_zero(&r->refcount);
+	return refcount_inc_not_zero(&r->refcount);
 }
 
 int p9_req_put(struct p9_req_t *r);
diff --git a/net/9p/client.c b/net/9p/client.c
index 8bba0d9cf9..0ee48e8b72 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -305,7 +305,7 @@ p9_tag_alloc(struct p9_client *c, int8_t type, unsigned int max_size)
 	 * callback), so p9_client_cb eats the second ref there
 	 * as the pointer is duplicated directly by virtqueue_add_sgs()
 	 */
-	refcount_set(&req->refcount.refcount, 2);
+	refcount_set(&req->refcount, 2);
 
 	return req;
 
@@ -370,18 +370,15 @@ static int p9_tag_remove(struct p9_client *c, struct p9_req_t *r)
 	return p9_req_put(r);
 }
 
-static void p9_req_free(struct kref *ref)
-{
-	struct p9_req_t *r = container_of(ref, struct p9_req_t, refcount);
-
-	p9_fcall_fini(&r->tc);
-	p9_fcall_fini(&r->rc);
-	kmem_cache_free(p9_req_cache, r);
-}
-
 int p9_req_put(struct p9_req_t *r)
 {
-	return kref_put(&r->refcount, p9_req_free);
+	if (refcount_dec_and_test(&r->refcount)) {
+		p9_fcall_fini(&r->tc);
+		p9_fcall_fini(&r->rc);
+		kmem_cache_free(p9_req_cache, r);
+		return 1;
+	}
+	return 0;
 }
 EXPORT_SYMBOL(p9_req_put);
 
-- 
2.36.1