[PATCH net-next v2 2/5] ipv6: mld: rename mldv2_mrc() and add mldv2_qqi()

Ujjal Roy
2026-03-30T19:16:42Z

Rename mldv2_mrc() to mldv2_mrd() as it used to calculate
the Maximum Response Delay from the Maximum Response Code.

Introduce a new API mldv2_qqi() to define the existing
calculation logic of QQI from QQIC. This also organizes
the existing mld_update_qi() API.

Added by e3f5b1704 ("net: ipv6: mld: get rid of MLDV2_MRC and simplify calculation").

Signed-off-by: Ujjal Roy <royujjal@gmail.com>
---
include/net/mld.h | 64 +++++++++++++++++++++++++++++++++------
net/bridge/br_multicast.c | 2 +-
net/ipv6/mcast.c | 19 ++----------
3 files changed, 58 insertions(+), 27 deletions(-)

diff --git a/include/net/mld.h b/include/net/mld.h
index c07359808493..5e093f9c75d9 100644
--- a/include/net/mld.h
+++ b/include/net/mld.h
@@ -89,29 +89,73 @@ struct mld2_query {
#define MLDV2_QQIC_EXP(value) (((value) >> 4) & 0x07)
#define MLDV2_QQIC_MAN(value) ((value) & 0x0f)

-#define MLD_EXP_MIN_LIMIT 32768UL
-#define MLDV1_MRD_MAX_COMPAT (MLD_EXP_MIN_LIMIT - 1)
+#define MLD_QQIC_MIN_THRESHOLD 128
+#define MLD_MRC_MIN_THRESHOLD 32768UL
+#define MLDV1_MRD_MAX_COMPAT (MLD_MRC_MIN_THRESHOLD - 1)

#define MLD_MAX_QUEUE 8
#define MLD_MAX_SKBS 32

-static inline unsigned long mldv2_mrc(const struct mld2_query *mlh2)
-{
- /* RFC3810, 5.1.3. Maximum Response Code */
- unsigned long ret, mc_mrc = ntohs(mlh2->mld2q_mrc);
+/* V2 exponential field decoding */

- if (mc_mrc < MLD_EXP_MIN_LIMIT) {
- ret = mc_mrc;
+/* Calculate Maximum Response Delay from Maximum Response Code
+ *
+ * RFC3810, 5.1.3. defines the decoding formula:
+ * 0 1 2 3 4 5 6 7 8 9 A B C D E F
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |1| exp | mant |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * Maximum Response Delay = (mant | 0x1000) << (exp+3)
+ */
+static inline unsigned long mldv2_mrd(const struct mld2_query *mlh2)
+{
+ /* RFC3810, relevant sections:
+ * - 5.1.3. Maximum Response Code
+ * - 9.3. Query Response Interval
+ */
+ unsigned long mc_mrc = ntohs(mlh2->mld2q_mrc);
+
+ if (mc_mrc < MLD_MRC_MIN_THRESHOLD) {
+ return mc_mrc;
} else {
unsigned long mc_man, mc_exp;

mc_exp = MLDV2_MRC_EXP(mc_mrc);
mc_man = MLDV2_MRC_MAN(mc_mrc);

- ret = (mc_man | 0x1000) << (mc_exp + 3);
+ return ((mc_man | 0x1000) << (mc_exp + 3));
}
+}

- return ret;
+/* Calculate Querier's Query Interval from Querier's Query Interval Code
+ *
+ * RFC3810, 5.1.9. defines the decoding formula:
+ * 0 1 2 3 4 5 6 7
+ * +-+-+-+-+-+-+-+-+
+ * |1| exp | mant |
+ * +-+-+-+-+-+-+-+-+
+ * QQI = (mant | 0x10) << (exp + 3)
+ */
+static inline unsigned long mldv2_qqi(const struct mld2_query *mlh2)
+{
+ /* RFC3810, relevant sections:
+ * - 5.1.9. QQIC (Querier's Query Interval Code)
+ * - 9.2. Query Interval
+ * - 9.12. Older Version Querier Present Timeout
+ * (the [Query Interval] in the last Query received)
+ */
+ unsigned long qqic = mlh2->mld2q_qqic;
+
+ if (qqic < MLD_QQIC_MIN_THRESHOLD) {
+ return qqic;
+ } else {
+ unsigned long mc_man, mc_exp;
+
+ mc_exp = MLDV2_QQIC_EXP(qqic);
+ mc_man = MLDV2_QQIC_MAN(qqic);
+
+ return ((mc_man | 0x10) << (mc_exp + 3));
+ }
}

#endif
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 9fec76e887bc..1438c023db62 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -3606,7 +3606,7 @@ static int br_ip6_multicast_query(struct net_bridge_mcast *brmctx,
mld2q->mld2q_suppress)
goto out;

- max_delay = max(msecs_to_jiffies(mldv2_mrc(mld2q)), 1UL);
+ max_delay = max(msecs_to_jiffies(mldv2_mrd(mld2q)), 1UL);
}

is_general_query = group && ipv6_addr_any(group);
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 3330adcf26db..6ddc18ac59b9 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1315,20 +1315,7 @@ static void mld_update_qi(struct inet6_dev *idev,
* - 9.12. Older Version Querier Present Timeout
* (the [Query Interval] in the last Query received)
*/
- unsigned long mc_qqi;
-
- if (mlh2->mld2q_qqic < 128) {
- mc_qqi = mlh2->mld2q_qqic;
- } else {
- unsigned long mc_man, mc_exp;
-
- mc_exp = MLDV2_QQIC_EXP(mlh2->mld2q_qqic);
- mc_man = MLDV2_QQIC_MAN(mlh2->mld2q_qqic);
-
- mc_qqi = (mc_man | 0x10) << (mc_exp + 3);
- }
-
- idev->mc_qi = mc_qqi * HZ;
+ idev->mc_qi = mldv2_qqi(mlh2) * HZ;
}

static void mld_update_qri(struct inet6_dev *idev,
@@ -1338,7 +1325,7 @@ static void mld_update_qri(struct inet6_dev *idev,
* - 5.1.3. Maximum Response Code
* - 9.3. Query Response Interval
*/
- idev->mc_qri = msecs_to_jiffies(mldv2_mrc(mlh2));
+ idev->mc_qri = msecs_to_jiffies(mldv2_mrd(mlh2));
}

static int mld_process_v1(struct inet6_dev *idev, struct mld_msg *mld,
@@ -1390,7 +1377,7 @@ static int mld_process_v1(struct inet6_dev *idev, struct mld_msg *mld,
static void mld_process_v2(struct inet6_dev *idev, struct mld2_query *mld,
unsigned long *max_delay)
{
- *max_delay = max(msecs_to_jiffies(mldv2_mrc(mld)), 1UL);
+ *max_delay = max(msecs_to_jiffies(mldv2_mrd(mld)), 1UL);

mld_update_qrv(idev, mld);
mld_update_qi(idev, mld);
--
2.43.0