diff mbox series

[v2,net-next,13/19] ip6mr: do not acquire mrt_lock before calling ip6mr_cache_unresolved

Message ID 20220623043449.1217288-14-edumazet@google.com (mailing list archive)
State Accepted
Commit db9eb7c8ae34c4acdb8a94c3566d1b4f4b5e7b1c
Delegated to: Netdev Maintainers
Headers show
Series ipmr: get rid of rwlocks | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count fail Series longer than 15 patches (and no cover letter)
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 2 this patch: 2
netdev/cc_maintainers warning 2 maintainers not CCed: yoshfuji@linux-ipv6.org dsahern@kernel.org
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 2 this patch: 2
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 53 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Eric Dumazet June 23, 2022, 4:34 a.m. UTC 
rcu_read_lock() protection is good enough.

ip6mr_cache_unresolved() uses a dedicated spinlock (mfc_unres_lock)

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv6/ip6mr.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index b4ad606e24bdaf12c233f642cee303f06ccfa4eb..089c26af3120d198ccfdda631294ed9712568ac0 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -730,7 +730,7 @@  static int mif6_delete(struct mr_table *mrt, int vifi, int notify,
 			if (VIF_EXISTS(mrt, tmp))
 				break;
 		}
-		mrt->maxvif = tmp + 1;
+		WRITE_ONCE(mrt->maxvif, tmp + 1);
 	}
 
 	write_unlock_bh(&mrt_lock);
@@ -927,7 +927,7 @@  static int mif6_add(struct net *net, struct mr_table *mrt,
 		WRITE_ONCE(mrt->mroute_reg_vif_num, vifi);
 #endif
 	if (vifi + 1 > mrt->maxvif)
-		mrt->maxvif = vifi + 1;
+		WRITE_ONCE(mrt->maxvif, vifi + 1);
 	write_unlock_bh(&mrt_lock);
 	call_ip6mr_vif_entry_notifiers(net, FIB_EVENT_VIF_ADD,
 				       v, dev, vifi, mrt->id);
@@ -2099,11 +2099,13 @@  static int ip6mr_forward2(struct net *net, struct mr_table *mrt,
 	return 0;
 }
 
+/* Called with mrt_lock or rcu_read_lock() */
 static int ip6mr_find_vif(struct mr_table *mrt, struct net_device *dev)
 {
 	int ct;
 
-	for (ct = mrt->maxvif - 1; ct >= 0; ct--) {
+	/* Pairs with WRITE_ONCE() in mif6_delete()/mif6_add() */
+	for (ct = READ_ONCE(mrt->maxvif) - 1; ct >= 0; ct--) {
 		if (rcu_access_pointer(mrt->vif_table[ct].dev) == dev)
 			break;
 	}
@@ -2249,7 +2251,6 @@  int ip6_mr_input(struct sk_buff *skb)
 		return err;
 	}
 
-	read_lock(&mrt_lock);
 	cache = ip6mr_cache_find(mrt,
 				 &ipv6_hdr(skb)->saddr, &ipv6_hdr(skb)->daddr);
 	if (!cache) {
@@ -2270,15 +2271,14 @@  int ip6_mr_input(struct sk_buff *skb)
 		vif = ip6mr_find_vif(mrt, dev);
 		if (vif >= 0) {
 			int err = ip6mr_cache_unresolved(mrt, vif, skb, dev);
-			read_unlock(&mrt_lock);
 
 			return err;
 		}
-		read_unlock(&mrt_lock);
 		kfree_skb(skb);
 		return -ENODEV;
 	}
 
+	read_lock(&mrt_lock);
 	ip6_mr_forward(net, mrt, dev, skb, cache);
 
 	read_unlock(&mrt_lock);