Re: [PATCH 00/14] replace call_rcu by kfree_rcu for simple kmem_cache_free callback

Julia Lawall
2024-10-09T17:09:08Z

Hello,

I have rerun the semantic patch that removes call_rcu calls in cases where
the callback function just does some pointer arithmetic and calls
kmem_cache_free. Let me know if this looks ok, and if so, I can make a
more formal patch submission.

This is against:

commit 75b607fab38d149f232f01eae5e6392b394dd659 (HEAD -> master, origin/master, origin/HEAD)
Merge: 5b7c893ed5ed e0ed52154e86
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date: Tue Oct 8 12:54:04 2024 -0700

Merge tag 'sched_ext-for-6.12-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext

julia

diff -u -p a/arch/powerpc/kvm/book3s_mmu_hpte.c b/arch/powerpc/kvm/book3s_mmu_hpte.c
--- a/arch/powerpc/kvm/book3s_mmu_hpte.c
+++ b/arch/powerpc/kvm/book3s_mmu_hpte.c
@@ -92,12 +92,6 @@ void kvmppc_mmu_hpte_cache_map(struct kv
spin_unlock(&vcpu3s->mmu_lock);
}

-static void free_pte_rcu(struct rcu_head *head)
-{
- struct hpte_cache *pte = container_of(head, struct hpte_cache, rcu_head);
- kmem_cache_free(hpte_cache, pte);
-}
-
static void invalidate_pte(struct kvm_vcpu *vcpu, struct hpte_cache *pte)
{
struct kvmppc_vcpu_book3s *vcpu3s = to_book3s(vcpu);
@@ -126,7 +120,7 @@ static void invalidate_pte(struct kvm_vc

spin_unlock(&vcpu3s->mmu_lock);

- call_rcu(&pte->rcu_head, free_pte_rcu);
+ kfree_rcu(pte, rcu_head);
}

static void kvmppc_mmu_pte_flush_all(struct kvm_vcpu *vcpu)
diff -u -p a/block/blk-ioc.c b/block/blk-ioc.c
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -32,13 +32,6 @@ static void get_io_context(struct io_con
atomic_long_inc(&ioc->refcount);
}

-static void icq_free_icq_rcu(struct rcu_head *head)
-{
- struct io_cq *icq = container_of(head, struct io_cq, __rcu_head);
-
- kmem_cache_free(icq->__rcu_icq_cache, icq);
-}
-
/*
* Exit an icq. Called with ioc locked for blk-mq, and with both ioc
* and queue locked for legacy.
@@ -102,7 +95,7 @@ static void ioc_destroy_icq(struct io_cq
*/
icq->__rcu_icq_cache = et->icq_cache;
icq->flags |= ICQ_DESTROYED;
- call_rcu(&icq->__rcu_head, icq_free_icq_rcu);
+ kfree_rcu(icq, __rcu_head);
}

/*
diff -u -p a/drivers/net/wireguard/allowedips.c b/drivers/net/wireguard/allowedips.c
--- a/drivers/net/wireguard/allowedips.c
+++ b/drivers/net/wireguard/allowedips.c
@@ -48,11 +48,6 @@ static void push_rcu(struct allowedips_n
}
}

-static void node_free_rcu(struct rcu_head *rcu)
-{
- kmem_cache_free(node_cache, container_of(rcu, struct allowedips_node, rcu));
-}
-
static void root_free_rcu(struct rcu_head *rcu)
{
struct allowedips_node *node, *stack[MAX_ALLOWEDIPS_DEPTH] = {
@@ -330,13 +325,13 @@ void wg_allowedips_remove_by_peer(struct
child = rcu_dereference_protected(
parent->bit[!(node->parent_bit_packed & 1)],
lockdep_is_held(lock));
- call_rcu(&node->rcu, node_free_rcu);
+ kfree_rcu(node, rcu);
if (!free_parent)
continue;
if (child)
child->parent_bit_packed = parent->parent_bit_packed;
*(struct allowedips_node **)(parent->parent_bit_packed & ~3UL) = child;
- call_rcu(&parent->rcu, node_free_rcu);
+ kfree_rcu(parent, rcu);
}
}

diff -u -p a/fs/ecryptfs/dentry.c b/fs/ecryptfs/dentry.c
--- a/fs/ecryptfs/dentry.c
+++ b/fs/ecryptfs/dentry.c
@@ -51,12 +51,6 @@ static int ecryptfs_d_revalidate(struct

struct kmem_cache *ecryptfs_dentry_info_cache;

-static void ecryptfs_dentry_free_rcu(struct rcu_head *head)
-{
- kmem_cache_free(ecryptfs_dentry_info_cache,
- container_of(head, struct ecryptfs_dentry_info, rcu));
-}
-
/**
* ecryptfs_d_release
* @dentry: The ecryptfs dentry
@@ -68,7 +62,7 @@ static void ecryptfs_d_release(struct de
struct ecryptfs_dentry_info *p = dentry->d_fsdata;
if (p) {
path_put(&p->lower_path);
- call_rcu(&p->rcu, ecryptfs_dentry_free_rcu);
+ kfree_rcu(p, rcu);
}
}

diff -u -p a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -572,13 +572,6 @@ opaque_hashval(const void *ptr, int nbyt
return x;
}

-static void nfsd4_free_file_rcu(struct rcu_head *rcu)
-{
- struct nfs4_file *fp = container_of(rcu, struct nfs4_file, fi_rcu);
-
- kmem_cache_free(file_slab, fp);
-}
-
void
put_nfs4_file(struct nfs4_file *fi)
{
@@ -586,7 +579,7 @@ put_nfs4_file(struct nfs4_file *fi)
nfsd4_file_hash_remove(fi);
WARN_ON_ONCE(!list_empty(&fi->fi_clnt_odstate));
WARN_ON_ONCE(!list_empty(&fi->fi_delegations));
- call_rcu(&fi->fi_rcu, nfsd4_free_file_rcu);
+ kfree_rcu(fi, fi_rcu);
}
}

diff -u -p a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -413,18 +413,11 @@ static struct k_itimer * alloc_posix_tim
return tmr;
}

-static void k_itimer_rcu_free(struct rcu_head *head)
-{
- struct k_itimer *tmr = container_of(head, struct k_itimer, rcu);
-
- kmem_cache_free(posix_timers_cache, tmr);
-}
-
static void posix_timer_free(struct k_itimer *tmr)
{
put_pid(tmr->it_pid);
sigqueue_free(tmr->sigq);
- call_rcu(&tmr->rcu, k_itimer_rcu_free);
+ kfree_rcu(tmr, rcu);
}

static void posix_timer_unhash_and_free(struct k_itimer *tmr)
diff -u -p a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -408,19 +408,6 @@ static void batadv_tt_global_size_dec(st
}

/**
- * batadv_tt_orig_list_entry_free_rcu() - free the orig_entry
- * @rcu: rcu pointer of the orig_entry
- */
-static void batadv_tt_orig_list_entry_free_rcu(struct rcu_head *rcu)
-{
- struct batadv_tt_orig_list_entry *orig_entry;
-
- orig_entry = container_of(rcu, struct batadv_tt_orig_list_entry, rcu);
-
- kmem_cache_free(batadv_tt_orig_cache, orig_entry);
-}
-
-/**
* batadv_tt_orig_list_entry_release() - release tt orig entry from lists and
* queue for free after rcu grace period
* @ref: kref pointer of the tt orig entry
@@ -433,7 +420,7 @@ static void batadv_tt_orig_list_entry_re
refcount);

batadv_orig_node_put(orig_entry->orig_node);
- call_rcu(&orig_entry->rcu, batadv_tt_orig_list_entry_free_rcu);
+ kfree_rcu(orig_entry, rcu);
}

/**
diff -u -p a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -73,13 +73,6 @@ static inline int has_expired(const stru
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
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 -u -p a/net/can/gw.c b/net/can/gw.c
--- a/net/can/gw.c
+++ b/net/can/gw.c
@@ -577,13 +577,6 @@ static inline void cgw_unregister_filter
gwj->ccgw.filter.can_mask, can_can_gw_rcv, gwj);
}

-static void cgw_job_free_rcu(struct rcu_head *rcu_head)
-{
- struct cgw_job *gwj = container_of(rcu_head, struct cgw_job, rcu);
-
- kmem_cache_free(cgw_cache, gwj);
-}
-
static int cgw_notifier(struct notifier_block *nb,
unsigned long msg, void *ptr)
{
@@ -603,7 +596,7 @@ static int cgw_notifier(struct notifier_
if (gwj->src.dev == dev || gwj->dst.dev == dev) {
hlist_del(&gwj->list);
cgw_unregister_filter(net, gwj);
- call_rcu(&gwj->rcu, cgw_job_free_rcu);
+ kfree_rcu(gwj, rcu);
}
}
}
@@ -1168,7 +1161,7 @@ static void cgw_remove_all_jobs(struct n
hlist_for_each_entry_safe(gwj, nx, &net->can.cgw_list, list) {
hlist_del(&gwj->list);
cgw_unregister_filter(net, gwj);
- call_rcu(&gwj->rcu, cgw_job_free_rcu);
+ kfree_rcu(gwj, rcu);
}
}

@@ -1236,7 +1229,7 @@ static int cgw_remove_job(struct sk_buff

hlist_del(&gwj->list);
cgw_unregister_filter(net, gwj);
- call_rcu(&gwj->rcu, cgw_job_free_rcu);
+ kfree_rcu(gwj, rcu);
err = 0;
break;
}
diff -u -p a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
--- 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 -u -p a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -128,11 +128,6 @@ static struct inet_peer *lookup(const st
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_pee
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 -u -p a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -198,16 +198,9 @@ static void node_free_immediate(struct n
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 -u -p a/net/ipv6/xfrm6_tunnel.c b/net/ipv6/xfrm6_tunnel.c
--- a/net/ipv6/xfrm6_tunnel.c
+++ b/net/ipv6/xfrm6_tunnel.c
@@ -178,12 +178,6 @@ __be32 xfrm6_tunnel_alloc_spi(struct net
}
EXPORT_SYMBOL(xfrm6_tunnel_alloc_spi);

-static void x6spi_destroy_rcu(struct rcu_head *head)
-{
- kmem_cache_free(xfrm6_tunnel_spi_kmem,
- container_of(head, struct xfrm6_tunnel_spi, rcu_head));
-}
-
static void xfrm6_tunnel_free_spi(struct net *net, xfrm_address_t *saddr)
{
struct xfrm6_tunnel_net *xfrm6_tn = xfrm6_tunnel_pernet(net);
@@ -200,7 +194,7 @@ static void xfrm6_tunnel_free_spi(struct
if (refcount_dec_and_test(&x6spi->refcnt)) {
hlist_del_rcu(&x6spi->list_byaddr);
hlist_del_rcu(&x6spi->list_byspi);
- call_rcu(&x6spi->rcu_head, x6spi_destroy_rcu);
+ kfree_rcu(x6spi, rcu_head);
break;
}
}
diff -u -p a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1584,14 +1584,6 @@ static int kcm_ioctl(struct socket *sock
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 *
knet->count--;
mutex_unlock(&knet->mutex);

- call_rcu(&mux->rcu, free_mux);
+ kfree_rcu(mux, rcu);
}

static void kcm_done(struct kcm_sock *kcm)
diff -u -p a/net/netfilter/nf_conncount.c b/net/netfilter/nf_conncount.c
--- a/net/netfilter/nf_conncount.c
+++ b/net/netfilter/nf_conncount.c
@@ -275,14 +275,6 @@ bool nf_conncount_gc_list(struct net *ne
}
EXPORT_SYMBOL_GPL(nf_conncount_gc_list);

-static void __tree_nodes_free(struct rcu_head *h)
-{
- struct nf_conncount_rb *rbconn;
-
- rbconn = container_of(h, struct nf_conncount_rb, rcu_head);
- kmem_cache_free(conncount_rb_cachep, rbconn);
-}
-
/* caller must hold tree nf_conncount_locks[] lock */
static void tree_nodes_free(struct rb_root *root,
struct nf_conncount_rb *gc_nodes[],
@@ -295,7 +287,7 @@ static void tree_nodes_free(struct rb_ro
spin_lock(&rbconn->list.list_lock);
if (!rbconn->list.count) {
rb_erase(&rbconn->node, root);
- call_rcu(&rbconn->rcu_head, __tree_nodes_free);
+ kfree_rcu(rbconn, rcu_head);
}
spin_unlock(&rbconn->list.list_lock);
}
diff -u -p a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c
--- a/net/netfilter/nf_conntrack_expect.c
+++ b/net/netfilter/nf_conntrack_expect.c
@@ -367,18 +367,10 @@ void nf_ct_expect_init(struct nf_conntra
}
EXPORT_SYMBOL_GPL(nf_ct_expect_init);

-static void nf_ct_expect_free_rcu(struct rcu_head *head)
-{
- struct nf_conntrack_expect *exp;
-
- exp = container_of(head, struct nf_conntrack_expect, rcu);
- kmem_cache_free(nf_ct_expect_cachep, exp);
-}
-
void nf_ct_expect_put(struct nf_conntrack_expect *exp)
{
if (refcount_dec_and_test(&exp->use))
- call_rcu(&exp->rcu, nf_ct_expect_free_rcu);
+ kfree_rcu(exp, rcu);
}
EXPORT_SYMBOL_GPL(nf_ct_expect_put);

diff -u -p a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -256,18 +256,11 @@ dsthash_alloc_init(struct xt_hashlimit_h
return ent;
}

-static void dsthash_free_rcu(struct rcu_head *head)
-{
- struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu);
-
- kmem_cache_free(hashlimit_cachep, ent);
-}
-
static inline void
dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
{
hlist_del_rcu(&ent->node);
- call_rcu(&ent->rcu, dsthash_free_rcu);
+ kfree_rcu(ent, rcu);
ht->count--;
}
static void htable_gc(struct work_struct *work);