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Message-Id: <20220622051255.700309-5-edumazet@google.com>
Date: Wed, 22 Jun 2022 05:12:40 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com,
Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 04/19] ipmr: ipmr_cache_report() changes
ipmr_cache_report() first argument can be marked const, and we change
the caller convention about which lock needs to be held.
Instead of read_lock(&mrt_lock), we can use rcu_read_lock().
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
net/ipv4/ipmr.c | 45 +++++++++++++++++++++++++++++----------------
1 file changed, 29 insertions(+), 16 deletions(-)
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 6710324497cae3bbc2fcdd12d6e1d44eed5215b3..8fe7a688cf41deeb99c7ca554f1788a956d2fdb9 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -106,7 +106,7 @@ static void ipmr_free_table(struct mr_table *mrt);
static void ip_mr_forward(struct net *net, struct mr_table *mrt,
struct net_device *dev, struct sk_buff *skb,
struct mfc_cache *cache, int local);
-static int ipmr_cache_report(struct mr_table *mrt,
+static int ipmr_cache_report(const struct mr_table *mrt,
struct sk_buff *pkt, vifi_t vifi, int assert);
static void mroute_netlink_event(struct mr_table *mrt, struct mfc_cache *mfc,
int cmd);
@@ -507,11 +507,15 @@ static netdev_tx_t reg_vif_xmit(struct sk_buff *skb, struct net_device *dev)
return err;
}
- read_lock(&mrt_lock);
dev->stats.tx_bytes += skb->len;
dev->stats.tx_packets++;
- ipmr_cache_report(mrt, skb, mrt->mroute_reg_vif_num, IGMPMSG_WHOLEPKT);
- read_unlock(&mrt_lock);
+ rcu_read_lock();
+
+ /* Pairs with WRITE_ONCE() in vif_add() and vif_delete() */
+ ipmr_cache_report(mrt, skb, READ_ONCE(mrt->mroute_reg_vif_num),
+ IGMPMSG_WHOLEPKT);
+
+ rcu_read_unlock();
kfree_skb(skb);
return NETDEV_TX_OK;
}
@@ -665,9 +669,10 @@ static int vif_delete(struct mr_table *mrt, int vifi, int notify,
vifi, mrt->id);
RCU_INIT_POINTER(v->dev, NULL);
- if (vifi == mrt->mroute_reg_vif_num)
- mrt->mroute_reg_vif_num = -1;
-
+ if (vifi == mrt->mroute_reg_vif_num) {
+ /* Pairs with READ_ONCE() in ipmr_cache_report() and reg_vif_xmit() */
+ WRITE_ONCE(mrt->mroute_reg_vif_num, -1);
+ }
if (vifi + 1 == mrt->maxvif) {
int tmp;
@@ -895,8 +900,10 @@ static int vif_add(struct net *net, struct mr_table *mrt,
write_lock_bh(&mrt_lock);
rcu_assign_pointer(v->dev, dev);
netdev_tracker_alloc(dev, &v->dev_tracker, GFP_ATOMIC);
- if (v->flags & VIFF_REGISTER)
- mrt->mroute_reg_vif_num = vifi;
+ if (v->flags & VIFF_REGISTER) {
+ /* Pairs with READ_ONCE() in ipmr_cache_report() and reg_vif_xmit() */
+ WRITE_ONCE(mrt->mroute_reg_vif_num, vifi);
+ }
if (vifi+1 > mrt->maxvif)
mrt->maxvif = vifi+1;
write_unlock_bh(&mrt_lock);
@@ -1005,9 +1012,9 @@ static void ipmr_cache_resolve(struct net *net, struct mr_table *mrt,
/* Bounce a cache query up to mrouted and netlink.
*
- * Called under mrt_lock.
+ * Called under rcu_read_lock().
*/
-static int ipmr_cache_report(struct mr_table *mrt,
+static int ipmr_cache_report(const struct mr_table *mrt,
struct sk_buff *pkt, vifi_t vifi, int assert)
{
const int ihl = ip_hdrlen(pkt);
@@ -1042,8 +1049,11 @@ static int ipmr_cache_report(struct mr_table *mrt,
msg->im_vif = vifi;
msg->im_vif_hi = vifi >> 8;
} else {
- msg->im_vif = mrt->mroute_reg_vif_num;
- msg->im_vif_hi = mrt->mroute_reg_vif_num >> 8;
+ /* Pairs with WRITE_ONCE() in vif_add() and vif_delete() */
+ int vif_num = READ_ONCE(mrt->mroute_reg_vif_num);
+
+ msg->im_vif = vif_num;
+ msg->im_vif_hi = vif_num >> 8;
}
ip_hdr(skb)->ihl = sizeof(struct iphdr) >> 2;
ip_hdr(skb)->tot_len = htons(ntohs(ip_hdr(pkt)->tot_len) +
@@ -1068,10 +1078,8 @@ static int ipmr_cache_report(struct mr_table *mrt,
skb->transport_header = skb->network_header;
}
- rcu_read_lock();
mroute_sk = rcu_dereference(mrt->mroute_sk);
if (!mroute_sk) {
- rcu_read_unlock();
kfree_skb(skb);
return -EINVAL;
}
@@ -1080,7 +1088,7 @@ static int ipmr_cache_report(struct mr_table *mrt,
/* Deliver to mrouted */
ret = sock_queue_rcv_skb(mroute_sk, skb);
- rcu_read_unlock();
+
if (ret < 0) {
net_warn_ratelimited("mroute: pending queue full, dropping entries\n");
kfree_skb(skb);
@@ -1090,6 +1098,7 @@ static int ipmr_cache_report(struct mr_table *mrt,
}
/* Queue a packet for resolution. It gets locked cache entry! */
+/* Called under rcu_read_lock() */
static int ipmr_cache_unresolved(struct mr_table *mrt, vifi_t vifi,
struct sk_buff *skb, struct net_device *dev)
{
@@ -1830,7 +1839,9 @@ static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt,
vif->bytes_out += skb->len;
vif_dev->stats.tx_bytes += skb->len;
vif_dev->stats.tx_packets++;
+ rcu_read_lock();
ipmr_cache_report(mrt, skb, vifi, IGMPMSG_WHOLEPKT);
+ rcu_read_unlock();
goto out_free;
}
@@ -1980,10 +1991,12 @@ static void ip_mr_forward(struct net *net, struct mr_table *mrt,
c->_c.mfc_un.res.last_assert +
MFC_ASSERT_THRESH)) {
c->_c.mfc_un.res.last_assert = jiffies;
+ rcu_read_lock();
ipmr_cache_report(mrt, skb, true_vifi, IGMPMSG_WRONGVIF);
if (mrt->mroute_do_wrvifwhole)
ipmr_cache_report(mrt, skb, true_vifi,
IGMPMSG_WRVIFWHOLE);
+ rcu_read_unlock();
}
goto dont_forward;
}
--
2.37.0.rc0.104.g0611611a94-goog
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