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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Victor Nogueira , cake@lists.bufferbloat.net Date: Thu, 8 Oct 2026 03:47:12 -0400 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-ID-Hash: ITQOSOTOLLYNFANCFLNFKEE3EFTE4SIY X-Message-ID-Hash: ITQOSOTOLLYNFANCFLNFKEE3EFTE4SIY X-MailFrom: jhs@mojatatu.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; loop; banned-address; emergency; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.10 Precedence: list Subject: [Cake] [PATCH net-next 4/4] net/sched/sch_cake: drop dead nla_nest_end() error check List-Id: Cake - FQ_codel the next generation Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: cake_dump_class_stats() closes the TCA_STATS_APP nest with if (nla_nest_end(d->skb, stats) < 0) return -1; nla_nest_end() never returns a negative value: it has a single `return skb->len;` and no error path (that is why the overflow-aware nla_nest_end_safe() helper was later added). The '< 0' test can never be true, so the 'return -1' is unreachable dead code. Drop the check and close the nest with the bare statement, matching the sibling cake nests in the same file. This issue was discovered while fixing a bug on the gate action, see: https://lore.kernel.org/netdev/QDISC-H19Z.v1.20261001053234@mojatatu.com/ Conditions to recreate the bug: - not runtime observable: the issue is found by inspection. Reviewed-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim --- net/sched/sch_cake.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c index 4caf9718c9bd..124f552023f8 100644 --- a/net/sched/sch_cake.c +++ b/net/sched/sch_cake.c @@ -3211,8 +3211,7 @@ static int cake_dump_class_stats(struct Qdisc *sch, unsigned long cl, READ_ONCE(flow->cvars.drop_next)))); } - if (nla_nest_end(d->skb, stats) < 0) - return -1; + nla_nest_end(d->skb, stats); } return 0; -- 2.43.0