diff mbox series

[net-next,2/3] ipv6: mcast: annotate data-races around mc->mca_sfcount[MCAST_EXCLUDE]

Message ID 20241210183352.86530-3-edumazet@google.com (mailing list archive)
State Accepted
Commit 626962911ad886f2b8e6d6f612289f9c7268b435
Delegated to: Netdev Maintainers
Headers show
Series ipv6: mcast: add data-race annotations | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 6 of 6 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
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, 38 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-12-12--00-00 (tests: 795)

Commit Message

Eric Dumazet Dec. 10, 2024, 6:33 p.m. UTC 
mc->mca_sfcount[MCAST_EXCLUDE] is read locklessly from
ipv6_chk_mcast_addr().

Add READ_ONCE() and WRITE_ONCE() annotations accordingly.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv6/mcast.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

Comments

David Ahern Dec. 11, 2024, 3:54 a.m. UTC | #1 
On 12/10/24 11:33 AM, Eric Dumazet wrote:
> mc->mca_sfcount[MCAST_EXCLUDE] is read locklessly from
> ipv6_chk_mcast_addr().
> 
> Add READ_ONCE() and WRITE_ONCE() annotations accordingly.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> ---
>  net/ipv6/mcast.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>
diff mbox series

Patch

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index afe707b6841d1ce84f11cc588200615b504a591d..09622142b0705bd81491f148dde4612c0f8fddb8 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1039,9 +1039,9 @@  bool ipv6_chk_mcast_addr(struct net_device *dev, const struct in6_addr *group,
 		if (psf)
 			rv = psf->sf_count[MCAST_INCLUDE] ||
 				psf->sf_count[MCAST_EXCLUDE] !=
-				mc->mca_sfcount[MCAST_EXCLUDE];
+				READ_ONCE(mc->mca_sfcount[MCAST_EXCLUDE]);
 		else
-			rv = mc->mca_sfcount[MCAST_EXCLUDE] != 0;
+			rv = READ_ONCE(mc->mca_sfcount[MCAST_EXCLUDE]) != 0;
 	} else {
 		rv = true; /* don't filter unspecified source */
 	}
@@ -2505,7 +2505,8 @@  static int ip6_mc_add_src(struct inet6_dev *idev, const struct in6_addr *pmca,
 	sf_markstate(pmc);
 	isexclude = pmc->mca_sfmode == MCAST_EXCLUDE;
 	if (!delta)
-		pmc->mca_sfcount[sfmode]++;
+		WRITE_ONCE(pmc->mca_sfcount[sfmode],
+			   pmc->mca_sfcount[sfmode] + 1);
 	err = 0;
 	for (i = 0; i < sfcount; i++) {
 		err = ip6_mc_add1_src(pmc, sfmode, &psfsrc[i]);
@@ -2516,7 +2517,8 @@  static int ip6_mc_add_src(struct inet6_dev *idev, const struct in6_addr *pmca,
 		int j;
 
 		if (!delta)
-			pmc->mca_sfcount[sfmode]--;
+			WRITE_ONCE(pmc->mca_sfcount[sfmode],
+				   pmc->mca_sfcount[sfmode] - 1);
 		for (j = 0; j < i; j++)
 			ip6_mc_del1_src(pmc, sfmode, &psfsrc[j]);
 	} else if (isexclude != (pmc->mca_sfcount[MCAST_EXCLUDE] != 0)) {
@@ -2561,7 +2563,8 @@  static void ip6_mc_clear_src(struct ifmcaddr6 *pmc)
 	RCU_INIT_POINTER(pmc->mca_sources, NULL);
 	pmc->mca_sfmode = MCAST_EXCLUDE;
 	pmc->mca_sfcount[MCAST_INCLUDE] = 0;
-	pmc->mca_sfcount[MCAST_EXCLUDE] = 1;
+	/* Paired with the READ_ONCE() from ipv6_chk_mcast_addr() */
+	WRITE_ONCE(pmc->mca_sfcount[MCAST_EXCLUDE], 1);
 }
 
 /* called with mc_lock */