ipmr: Convert mr_table.cache_resolve_queue_len to u32.

mr_table.cache_resolve_queue_len is always updated under
spin_lock_bh(&mfc_unres_lock).

Let's convert it to u32.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260609222013.1550355-1-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 18 insertions, 14 deletions

diff --git a/include/linux/mroute_base.h b/include/linux/mroute_base.h
index 5d75cc5b057e..4d55827e9705 100644
--- a/include/linux/mroute_base.h
+++ b/include/linux/mroute_base.h
@@ -256,7 +256,7 @@ struct mr_table {
 	struct rhltable		mfc_hash;
 	struct list_head	mfc_cache_list;
 	int			maxvif;
-	atomic_t		cache_resolve_queue_len;
+	u32			cache_resolve_queue_len;
 	bool			mroute_do_assert;
 	bool			mroute_do_pim;
 	bool			mroute_do_wrvifwhole;
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 78dbeecf71bb..1d9a4ac14fce 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -761,7 +761,8 @@ static void ipmr_destroy_unres(struct mr_table *mrt, struct mfc_cache *c)
 	struct sk_buff *skb;
 	struct nlmsgerr *e;
 
-	atomic_dec(&mrt->cache_resolve_queue_len);
+	WRITE_ONCE(mrt->cache_resolve_queue_len,
+		   mrt->cache_resolve_queue_len - 1);
 
 	while ((skb = skb_dequeue(&c->_c.mfc_un.unres.unresolved))) {
 		if (ip_hdr(skb)->version == 0) {
@@ -1180,11 +1181,12 @@ static int ipmr_cache_unresolved(struct mr_table *mrt, vifi_t vifi,
 		if (err < 0)
 			goto err;
 
-		atomic_inc(&mrt->cache_resolve_queue_len);
+		WRITE_ONCE(mrt->cache_resolve_queue_len,
+			   mrt->cache_resolve_queue_len + 1);
 		list_add(&c->_c.list, &mrt->mfc_unres_queue);
 		mroute_netlink_event(mrt, c, RTM_NEWROUTE);
 
-		if (atomic_read(&mrt->cache_resolve_queue_len) == 1)
+		if (mrt->cache_resolve_queue_len == 1)
 			mod_timer(&mrt->ipmr_expire_timer,
 				  c->_c.mfc_un.unres.expires);
 	}
@@ -1297,7 +1299,8 @@ static int ipmr_mfc_add(struct net *net, struct mr_table *mrt,
 		if (uc->mfc_origin == c->mfc_origin &&
 		    uc->mfc_mcastgrp == c->mfc_mcastgrp) {
 			list_del(&_uc->list);
-			atomic_dec(&mrt->cache_resolve_queue_len);
+			WRITE_ONCE(mrt->cache_resolve_queue_len,
+				   mrt->cache_resolve_queue_len - 1);
 			found = true;
 			break;
 		}
@@ -1356,7 +1359,7 @@ static void mroute_clean_tables(struct mr_table *mrt, int flags,
 	}
 
 	if (flags & MRT_FLUSH_MFC) {
-		if (atomic_read(&mrt->cache_resolve_queue_len) != 0 || !check_net(net)) {
+		if (READ_ONCE(mrt->cache_resolve_queue_len) || !check_net(net)) {
 			spin_lock_bh(&mfc_unres_lock);
 			list_for_each_entry_safe(c, tmp, &mrt->mfc_unres_queue, list) {
 				list_del(&c->list);
@@ -2962,10 +2965,9 @@ static int ipmr_rtm_route(struct sk_buff *skb, struct nlmsghdr *nlh,
 
 static bool ipmr_fill_table(struct mr_table *mrt, struct sk_buff *skb)
 {
-	u32 queue_len = atomic_read(&mrt->cache_resolve_queue_len);
-
 	if (nla_put_u32(skb, IPMRA_TABLE_ID, mrt->id) ||
-	    nla_put_u32(skb, IPMRA_TABLE_CACHE_RES_QUEUE_LEN, queue_len) ||
+	    nla_put_u32(skb, IPMRA_TABLE_CACHE_RES_QUEUE_LEN,
+			READ_ONCE(mrt->cache_resolve_queue_len)) ||
 	    nla_put_s32(skb, IPMRA_TABLE_MROUTE_REG_VIF_NUM,
 			READ_ONCE(mrt->mroute_reg_vif_num)) ||
 	    nla_put_u8(skb, IPMRA_TABLE_MROUTE_DO_ASSERT,
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 5a4816225fb1..604a58838901 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -817,7 +817,8 @@ static void ip6mr_destroy_unres(struct mr_table *mrt, struct mfc6_cache *c)
 	struct net *net = read_pnet(&mrt->net);
 	struct sk_buff *skb;
 
-	atomic_dec(&mrt->cache_resolve_queue_len);
+	WRITE_ONCE(mrt->cache_resolve_queue_len,
+		   mrt->cache_resolve_queue_len - 1);
 
 	while ((skb = skb_dequeue(&c->_c.mfc_un.unres.unresolved)) != NULL) {
 		if (ipv6_hdr(skb)->version == 0) {
@@ -1225,7 +1226,8 @@ static int ip6mr_cache_unresolved(struct mr_table *mrt, mifi_t mifi,
 		if (err < 0)
 			goto err;
 
-		atomic_inc(&mrt->cache_resolve_queue_len);
+		WRITE_ONCE(mrt->cache_resolve_queue_len,
+			   mrt->cache_resolve_queue_len + 1);
 		list_add(&c->_c.list, &mrt->mfc_unres_queue);
 		mr6_netlink_event(mrt, c, RTM_NEWROUTE);
 
@@ -1538,7 +1540,8 @@ static int ip6mr_mfc_add(struct net *net, struct mr_table *mrt,
 		if (ipv6_addr_equal(&uc->mf6c_origin, &c->mf6c_origin) &&
 		    ipv6_addr_equal(&uc->mf6c_mcastgrp, &c->mf6c_mcastgrp)) {
 			list_del(&_uc->list);
-			atomic_dec(&mrt->cache_resolve_queue_len);
+			WRITE_ONCE(mrt->cache_resolve_queue_len,
+				   mrt->cache_resolve_queue_len - 1);
 			found = true;
 			break;
 		}
@@ -1599,8 +1602,7 @@ static void mroute_clean_tables(struct mr_table *mrt, int flags,
 	}
 
 	if (flags & MRT6_FLUSH_MFC) {
-		if (atomic_read(&mrt->cache_resolve_queue_len) != 0 ||
-		    !check_net(net)) {
+		if (READ_ONCE(mrt->cache_resolve_queue_len) || !check_net(net)) {
 			spin_lock_bh(&mfc_unres_lock);
 			list_for_each_entry_safe(c, tmp, &mrt->mfc_unres_queue, list) {
 				list_del(&c->list);