[PATCH iproute2-next] tc: use ll_init_map() only when needed

Eric Dumazet
2026-04-28T08:28:54Z

Some setups can have thousands of devices.

ll_init_map() is rather expensive for them.

Only call ll_init_map() in the following cases:

1) tc runs in batch mode.
2) tc runs in monitor mode.
3) tc dumps qdiscs/classes/filters for all netdev.

This greatly reduces RTNL pressure on common operations.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
tc/f_route.c | 1 -
tc/m_mirred.c | 2 --
tc/tc.c | 1 +
tc/tc_class.c | 6 ++----
tc/tc_filter.c | 32 ++++++++++++++++----------------
tc/tc_qdisc.c | 5 ++---
6 files changed, 21 insertions(+), 26 deletions(-)

diff --git a/tc/f_route.c b/tc/f_route.c
index 96b99b06be179c90dfb0d24d9577b5206dd98ef1..c234ddf0cb9309556844c85047d0f9ef53a2fd7b 100644
--- a/tc/f_route.c
+++ b/tc/f_route.c
@@ -76,7 +76,6 @@ static int route_parse_opt(const struct filter_util *qu, char *handle, int argc,
__u32 id;

NEXT_ARG();
- ll_init_map(&rth);
if ((id = ll_name_to_index(*argv)) <= 0) {
fprintf(stderr, "Illegal \"fromif\"\n");
return -1;
diff --git a/tc/m_mirred.c b/tc/m_mirred.c
index f4da3c76284460d7f4bb73c7c3c172732f054632..e9ae5199432e828026f15ce226c5f5f84998c660 100644
--- a/tc/m_mirred.c
+++ b/tc/m_mirred.c
@@ -213,8 +213,6 @@ parse_direction(const struct action_util *a, int *argc_p, char ***argv_p,
if (d[0]) {
int idx;

- ll_init_map(&rth);
-
idx = ll_name_to_index(d);
if (!idx)
return nodev(d);
diff --git a/tc/tc.c b/tc/tc.c
index 0fc658c881f0f553f1f1f8d87b46943d4d0eed8f..7d69e4d533a98b9c071cb954443a049a52252f2c 100644
--- a/tc/tc.c
+++ b/tc/tc.c
@@ -243,6 +243,7 @@ static int batch(const char *name)
return -1;
}

+ ll_init_map(&rth);
ret = do_batch(name, force, tc_batch_cmd, NULL);

rtnl_close(&rth);
diff --git a/tc/tc_class.c b/tc/tc_class.c
index 6d707d8c924f4b5e90201d4de8e9779f82ce17f3..9aace019e6c8b96fb51edb4fe89bea5b7469beed 100644
--- a/tc/tc_class.c
+++ b/tc/tc_class.c
@@ -136,11 +136,11 @@ static int tc_class_modify(int cmd, unsigned int flags, int argc, char **argv)
}

if (d[0]) {
- ll_init_map(&rth);
-
req.t.tcm_ifindex = ll_name_to_index(d);
if (!req.t.tcm_ifindex)
return -nodev(d);
+ } else {
+ ll_init_map(&rth);
}

if (rtnl_talk(&rth, &req.n, NULL) < 0)
@@ -437,8 +437,6 @@ static int tc_class_list(int argc, char **argv)
argc--; argv++;
}

- ll_init_map(&rth);
-
if (d[0]) {
t.tcm_ifindex = ll_name_to_index(d);
if (!t.tcm_ifindex)
diff --git a/tc/tc_filter.c b/tc/tc_filter.c
index 7db850bda11a3408ec66b457c9fc590f3a734f65..be70e360849e5058192640da0f061810a99e2ea8 100644
--- a/tc/tc_filter.c
+++ b/tc/tc_filter.c
@@ -188,16 +188,17 @@ static int tc_filter_modify(int cmd, unsigned int flags, int argc, char **argv)
addattr_l(&req.n, sizeof(req), TCA_KIND, k, strlen(k)+1);

if (d[0]) {
- ll_init_map(&rth);
-
req.t.tcm_ifindex = ll_name_to_index(d);
if (req.t.tcm_ifindex == 0) {
fprintf(stderr, "Cannot find device \"%s\"\n", d);
return 1;
}
- } else if (block_index) {
- req.t.tcm_ifindex = TCM_IFINDEX_MAGIC_BLOCK;
- req.t.tcm_block_index = block_index;
+ } else {
+ ll_init_map(&rth);
+ if (block_index) {
+ req.t.tcm_ifindex = TCM_IFINDEX_MAGIC_BLOCK;
+ req.t.tcm_block_index = block_index;
+ }
}

if (q) {
@@ -539,8 +540,6 @@ static int tc_filter_get(int cmd, unsigned int flags, int argc, char **argv)
}

if (d[0]) {
- ll_init_map(&rth);
-
req.t.tcm_ifindex = ll_name_to_index(d);
if (!req.t.tcm_ifindex)
return -nodev(d);
@@ -704,21 +703,22 @@ static int tc_filter_list(int cmd, int argc, char **argv)

req.t.tcm_info = TC_H_MAKE(prio<<16, protocol);

- ll_init_map(&rth);
-
if (d[0]) {
req.t.tcm_ifindex = ll_name_to_index(d);
if (!req.t.tcm_ifindex)
return -nodev(d);
filter_ifindex = req.t.tcm_ifindex;
- } else if (block_index) {
- if (!tc_qdisc_block_exists(block_index)) {
- fprintf(stderr, "Cannot find block \"%u\"\n", block_index);
- return 1;
+ } else {
+ ll_init_map(&rth);
+ if (block_index) {
+ if (!tc_qdisc_block_exists(block_index)) {
+ fprintf(stderr, "Cannot find block \"%u\"\n", block_index);
+ return 1;
+ }
+ req.t.tcm_ifindex = TCM_IFINDEX_MAGIC_BLOCK;
+ req.t.tcm_block_index = block_index;
+ filter_block_index = block_index;
}
- req.t.tcm_ifindex = TCM_IFINDEX_MAGIC_BLOCK;
- req.t.tcm_block_index = block_index;
- filter_block_index = block_index;
}

if (filter_chain_index_set)
diff --git a/tc/tc_qdisc.c b/tc/tc_qdisc.c
index 7eb9a31baa31fb91a8141c9eca1135e76a52fa8b..252ea861f249a5a71cf782389776e68c3e48c6cc 100644
--- a/tc/tc_qdisc.c
+++ b/tc/tc_qdisc.c
@@ -193,8 +193,6 @@ static int tc_qdisc_modify(int cmd, unsigned int flags, int argc, char **argv)
if (d[0]) {
int idx;

- ll_init_map(&rth);
-
idx = ll_name_to_index(d);
if (!idx)
return -nodev(d);
@@ -411,13 +409,14 @@ static int tc_qdisc_list(int argc, char **argv)
argc--; argv++;
}

- ll_init_map(&rth);

if (d[0]) {
req.t.tcm_ifindex = ll_name_to_index(d);
if (!req.t.tcm_ifindex)
return -nodev(d);
filter_ifindex = req.t.tcm_ifindex;
+ } else {
+ ll_init_map(&rth);
}

if (dump_invisible) {
--
2.54.0.545.g6539524ca2-goog