diff mbox series

[v2,net-next,05/19] ipmr: do not acquire mrt_lock in __pim_rcv()

Message ID 20220623043449.1217288-6-edumazet@google.com (mailing list archive)
State Accepted
Commit 121fefc669bf6f603bbda380c91d788405bc4f1f
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: 4 this patch: 4
netdev/cc_maintainers warning 2 maintainers not CCed: yoshfuji@linux-ipv6.org dsahern@kernel.org
netdev/build_clang success Errors and warnings before: 6 this patch: 6
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: 4 this patch: 4
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 22 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 more than enough.

vif_dev_read() supports either mrt_lock or rcu_read_lock().

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv4/ipmr.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 8fe7a688cf41deeb99c7ca554f1788a956d2fdb9..8a94f9a459cd077d74b5e38c3d2f248620d4ecfc 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -582,6 +582,7 @@  static int __pim_rcv(struct mr_table *mrt, struct sk_buff *skb,
 {
 	struct net_device *reg_dev = NULL;
 	struct iphdr *encap;
+	int vif_num;
 
 	encap = (struct iphdr *)(skb_transport_header(skb) + pimlen);
 	/* Check that:
@@ -594,11 +595,10 @@  static int __pim_rcv(struct mr_table *mrt, struct sk_buff *skb,
 	    ntohs(encap->tot_len) + pimlen > skb->len)
 		return 1;
 
-	read_lock(&mrt_lock);
-	if (mrt->mroute_reg_vif_num >= 0)
-		reg_dev = vif_dev_read(&mrt->vif_table[mrt->mroute_reg_vif_num]);
-	read_unlock(&mrt_lock);
-
+	/* Pairs with WRITE_ONCE() in vif_add()/vid_delete() */
+	vif_num = READ_ONCE(mrt->mroute_reg_vif_num);
+	if (vif_num >= 0)
+		reg_dev = vif_dev_read(&mrt->vif_table[vif_num]);
 	if (!reg_dev)
 		return 1;