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

From: Paul E. McKenney
Date: Wed Oct 09 2024 - 17:02:41 EST

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In reply to: Julia Lawall: "Re: [PATCH 00/14] replace call_rcu by kfree_rcu for simple kmem_cache_free callback"
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On Wed, Oct 09, 2024 at 07:08:58PM +0200, Julia Lawall wrote:
> 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.

They look good to me, thank you!

Thanx, Paul

> This is against:
>
> commit 75b607fab38d149f232f01eae5e6392b394dd659 (HEAD -> master, origin/master, origin/HEAD)
> Merge: 5b7c893ed5ed e0ed52154e86
> Author: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> 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);

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