From 646679881a02a15a0915f4cd18dff6cecb8960fc Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 23 Jun 2022 04:34:34 +0000 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- 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 6710324..8fe7a68 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; } -- 2.7.4