Merge branch 'replace-call_rcu-by-kfree_rcu-for-simple-kmem_cache_free-callback'

Julia Lawall says:

====================
replace call_rcu by kfree_rcu for simple kmem_cache_free callback

Since SLOB was removed and since
commit 6c6c47b063b5 ("mm, slab: call kvfree_rcu_barrier() from kmem_cache_destroy()"),
it is not necessary to use call_rcu when the callback only performs
kmem_cache_free. Use kfree_rcu() directly.

The changes were done using the following Coccinelle semantic patch.
This semantic patch is designed to ignore cases where the callback
function is used in another way.

// <smpl>

@r@
expression e;
local idexpression e2;
identifier cb,f,g;
position p;
@@

(
call_rcu(...,e2)
|
call_rcu(&e->f,cb@p)
|
call_rcu(&e->f.g,cb@p)
)

@r1@
type T,T1;
identifier x,r.cb;
@@

 cb(...) {
(
   kmem_cache_free(...);
|
   T x = ...;
   kmem_cache_free(...,(T1)x);
|
   T x;
   x = ...;
   kmem_cache_free(...,(T1)x);
)
 }

@s depends on r1@
position p != r.p;
identifier r.cb;
@@

 cb@p

@script:ocaml@
cb << r.cb;
p << s.p;
@@

Printf.eprintf "Other use of %s at %s:%d\n" cb (List.hd p).file (List.hd p).line

@depends on r1 && !s@
expression e;
identifier r.cb,f,g;
position r.p;
@@

(
- call_rcu(&e->f,cb@p)
+ kfree_rcu(e,f)
|
- call_rcu(&e->f.g,cb@p)
+ kfree_rcu(e,f.g)
)

@r1a depends on !s@
type T,T1;
identifier x,r.cb;
@@

- cb(...) {
(
-  kmem_cache_free(...);
|
-  T x = ...;
-  kmem_cache_free(...,(T1)x);
|
-  T x;
-  x = ...;
-  kmem_cache_free(...,(T1)x);
)
- }

@r2 depends on !r1@
identifier r.cb;
@@

cb(...) {
 ...
}

@script:ocaml depends on !r1 && !r2@
cb << r.cb;
@@

Printf.eprintf "need definition for %s\n" cb
// </smpl>
====================

Acked-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Link: https://patch.msgid.link/20241013201704.49576-1-Julia.Lawall@inria.fr
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

5 files changed, 6 insertions, 39 deletions

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 642b8ccaae8e..1cd7bade9b3b 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -73,13 +73,6 @@ static inline int has_expired(const struct net_bridge *br,
 	       time_before_eq(fdb->updated + hold_time(br), jiffies);
 }
 
-static void fdb_rcu_free(struct rcu_head *head)
-{
-	struct net_bridge_fdb_entry *ent
-		= container_of(head, struct net_bridge_fdb_entry, rcu);
-	kmem_cache_free(br_fdb_cache, ent);
-}
-
 static int fdb_to_nud(const struct net_bridge *br,
 		      const struct net_bridge_fdb_entry *fdb)
 {
@@ -329,7 +322,7 @@ static void fdb_delete(struct net_bridge *br, struct net_bridge_fdb_entry *f,
 	if (test_and_clear_bit(BR_FDB_DYNAMIC_LEARNED, &f->flags))
 		atomic_dec(&br->fdb_n_learned);
 	fdb_notify(br, f, RTM_DELNEIGH, swdev_notify);
-	call_rcu(&f->rcu, fdb_rcu_free);
+	kfree_rcu(f, rcu);
 }
 
 /* Delete a local entry if no other port had the same address.
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 09e31757e96c..161f5526b86c 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -292,15 +292,9 @@ static const int inflate_threshold = 50;
 static const int halve_threshold_root = 15;
 static const int inflate_threshold_root = 30;
 
-static void __alias_free_mem(struct rcu_head *head)
-{
-	struct fib_alias *fa = container_of(head, struct fib_alias, rcu);
-	kmem_cache_free(fn_alias_kmem, fa);
-}
-
 static inline void alias_free_mem_rcu(struct fib_alias *fa)
 {
-	call_rcu(&fa->rcu, __alias_free_mem);
+	kfree_rcu(fa, rcu);
 }
 
 #define TNODE_VMALLOC_MAX \
diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index 5bd759963451..5ab56f4cb529 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -128,11 +128,6 @@ static struct inet_peer *lookup(const struct inetpeer_addr *daddr,
 	return NULL;
 }
 
-static void inetpeer_free_rcu(struct rcu_head *head)
-{
-	kmem_cache_free(peer_cachep, container_of(head, struct inet_peer, rcu));
-}
-
 /* perform garbage collect on all items stacked during a lookup */
 static void inet_peer_gc(struct inet_peer_base *base,
 			 struct inet_peer *gc_stack[],
@@ -168,7 +163,7 @@ static void inet_peer_gc(struct inet_peer_base *base,
 		if (p) {
 			rb_erase(&p->rb_node, &base->rb_root);
 			base->total--;
-			call_rcu(&p->rcu, inetpeer_free_rcu);
+			kfree_rcu(p, rcu);
 		}
 	}
 }
@@ -242,7 +237,7 @@ void inet_putpeer(struct inet_peer *p)
 	WRITE_ONCE(p->dtime, (__u32)jiffies);
 
 	if (refcount_dec_and_test(&p->refcnt))
-		call_rcu(&p->rcu, inetpeer_free_rcu);
+		kfree_rcu(p, rcu);
 }
 EXPORT_SYMBOL_GPL(inet_putpeer);
 
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index cea160b249d2..c9da10d971fa 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -198,16 +198,9 @@ static void node_free_immediate(struct net *net, struct fib6_node *fn)
 	net->ipv6.rt6_stats->fib_nodes--;
 }
 
-static void node_free_rcu(struct rcu_head *head)
-{
-	struct fib6_node *fn = container_of(head, struct fib6_node, rcu);
-
-	kmem_cache_free(fib6_node_kmem, fn);
-}
-
 static void node_free(struct net *net, struct fib6_node *fn)
 {
-	call_rcu(&fn->rcu, node_free_rcu);
+	kfree_rcu(fn, rcu);
 	net->ipv6.rt6_stats->fib_nodes--;
 }
 
diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index d4118c796290..24aec295a51c 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1584,14 +1584,6 @@ static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 	return err;
 }
 
-static void free_mux(struct rcu_head *rcu)
-{
-	struct kcm_mux *mux = container_of(rcu,
-	    struct kcm_mux, rcu);
-
-	kmem_cache_free(kcm_muxp, mux);
-}
-
 static void release_mux(struct kcm_mux *mux)
 {
 	struct kcm_net *knet = mux->knet;
@@ -1619,7 +1611,7 @@ static void release_mux(struct kcm_mux *mux)
 	knet->count--;
 	mutex_unlock(&knet->mutex);
 
-	call_rcu(&mux->rcu, free_mux);
+	kfree_rcu(mux, rcu);
 }
 
 static void kcm_done(struct kcm_sock *kcm)