ipv6: mcast: annotate data-race around psf->sf_count[MCAST_XXX]

psf->sf_count[MCAST_XXX] fields are read locklessly from
ipv6_chk_mcast_addr() and igmp6_mcf_seq_show().

Add READ_ONCE() and WRITE_ONCE() annotations accordingly.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20241210183352.86530-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 09622142b0705bd81491f148dde4612c0f8fddb8..5ca8692d565d5055eeebef2a547ced217d81c7d4 100644 (file)
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1037,8 +1037,8 @@ bool ipv6_chk_mcast_addr(struct net_device *dev, const struct in6_addr *group,
                                break;
                }
                if (psf)
-                       rv = psf->sf_count[MCAST_INCLUDE] ||
-                               psf->sf_count[MCAST_EXCLUDE] !=
+                       rv = READ_ONCE(psf->sf_count[MCAST_INCLUDE]) ||
+                               READ_ONCE(psf->sf_count[MCAST_EXCLUDE]) !=
                                READ_ONCE(mc->mca_sfcount[MCAST_EXCLUDE]);
                else
                        rv = READ_ONCE(mc->mca_sfcount[MCAST_EXCLUDE]) != 0;
@@ -2287,7 +2287,7 @@ static int ip6_mc_del1_src(struct ifmcaddr6 *pmc, int sfmode,
                /* source filter not found, or count wrong =>  bug */
                return -ESRCH;
        }
-       psf->sf_count[sfmode]--;
+       WRITE_ONCE(psf->sf_count[sfmode], psf->sf_count[sfmode] - 1);
        if (!psf->sf_count[MCAST_INCLUDE] && !psf->sf_count[MCAST_EXCLUDE]) {
                struct inet6_dev *idev = pmc->idev;
 
@@ -2393,7 +2393,7 @@ static int ip6_mc_add1_src(struct ifmcaddr6 *pmc, int sfmode,
                        rcu_assign_pointer(pmc->mca_sources, psf);
                }
        }
-       psf->sf_count[sfmode]++;
+       WRITE_ONCE(psf->sf_count[sfmode], psf->sf_count[sfmode] + 1);
        return 0;
 }
 
@@ -3079,8 +3079,8 @@ static int igmp6_mcf_seq_show(struct seq_file *seq, void *v)
                           state->dev->ifindex, state->dev->name,
                           &state->im->mca_addr,
                           &psf->sf_addr,
-                          psf->sf_count[MCAST_INCLUDE],
-                          psf->sf_count[MCAST_EXCLUDE]);
+                          READ_ONCE(psf->sf_count[MCAST_INCLUDE]),
+                          READ_ONCE(psf->sf_count[MCAST_EXCLUDE]));
        }
        return 0;
 }