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Message-ID: <CAM0EoMn+7tntXK10eT5twh6Bc62Gx2tE+3beVY99h6EMnFs6AQ@mail.gmail.com>
Date: Sat, 9 Nov 2024 07:50:53 -0500
From: Jamal Hadi Salim <jhs@...atatu.com>
To: Alexandre Ferrieux <alexandre.ferrieux@...il.com>
Cc: Eric Dumazet <edumazet@...gle.com>, Cong Wang <xiyou.wangcong@...il.com>,
Jiri Pirko <jiri@...nulli.us>, alexandre.ferrieux@...nge.com,
Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH net v6] net: sched: cls_u32: Fix u32's systematic failure
to free IDR entries for hnodes.
On Fri, Nov 8, 2024 at 9:12 AM Alexandre Ferrieux
<alexandre.ferrieux@...il.com> wrote:
>
> To generate hnode handles (in gen_new_htid()), u32 uses IDR and
> encodes the returned small integer into a structured 32-bit
> word. Unfortunately, at disposal time, the needed decoding
> is not done. As a result, idr_remove() fails, and the IDR
> fills up. Since its size is 2048, the following script ends up
> with "Filter already exists":
>
> tc filter add dev myve $FILTER1
> tc filter add dev myve $FILTER2
> for i in {1..2048}
> do
> echo $i
> tc filter del dev myve $FILTER2
> tc filter add dev myve $FILTER2
> done
>
> This patch adds the missing decoding logic for handles that
> deserve it, along with a corresponding tdc test.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Reviewed-by: Eric Dumazet <edumazet@...gle.com>
> Signed-off-by: Alexandre Ferrieux <alexandre.ferrieux@...nge.com>
Ok, looks good.
Please split the test into a separate patch targeting net-next. Also
your "Fixes" should be:
commit e7614370d6f04711c4e4b48f7055e5008fa4ed42
When you send the next version please include my Acked-by:
cheers,
jamal
> ---
> v6: big speedup of the tdc test with batch tc
> v5: fix title - again
> v4: add tdc test
> v3: prepend title with subsystem ident
> v2: use u32 type in handle encoder/decoder
>
> net/sched/cls_u32.c | 18 ++++++++++----
> .../tc-testing/tc-tests/filters/u32.json | 24 +++++++++++++++++++
> 2 files changed, 38 insertions(+), 4 deletions(-)
>
> diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
> index 9412d88a99bc..6da94b809926 100644
> --- a/net/sched/cls_u32.c
> +++ b/net/sched/cls_u32.c
> @@ -41,6 +41,16 @@
> #include <linux/idr.h>
> #include <net/tc_wrapper.h>
>
> +static inline u32 handle2id(u32 h)
> +{
> + return ((h & 0x80000000) ? ((h >> 20) & 0x7FF) : h);
> +}
> +
> +static inline u32 id2handle(u32 id)
> +{
> + return (id | 0x800U) << 20;
> +}
> +
> struct tc_u_knode {
> struct tc_u_knode __rcu *next;
> u32 handle;
> @@ -310,7 +320,7 @@ static u32 gen_new_htid(struct tc_u_common *tp_c, struct tc_u_hnode *ptr)
> int id = idr_alloc_cyclic(&tp_c->handle_idr, ptr, 1, 0x7FF, GFP_KERNEL);
> if (id < 0)
> return 0;
> - return (id | 0x800U) << 20;
> + return id2handle(id);
> }
>
> static struct hlist_head *tc_u_common_hash;
> @@ -360,7 +370,7 @@ static int u32_init(struct tcf_proto *tp)
> return -ENOBUFS;
>
> refcount_set(&root_ht->refcnt, 1);
> - root_ht->handle = tp_c ? gen_new_htid(tp_c, root_ht) : 0x80000000;
> + root_ht->handle = tp_c ? gen_new_htid(tp_c, root_ht) : id2handle(0);
> root_ht->prio = tp->prio;
> root_ht->is_root = true;
> idr_init(&root_ht->handle_idr);
> @@ -612,7 +622,7 @@ static int u32_destroy_hnode(struct tcf_proto *tp, struct tc_u_hnode *ht,
> if (phn == ht) {
> u32_clear_hw_hnode(tp, ht, extack);
> idr_destroy(&ht->handle_idr);
> - idr_remove(&tp_c->handle_idr, ht->handle);
> + idr_remove(&tp_c->handle_idr, handle2id(ht->handle));
> RCU_INIT_POINTER(*hn, ht->next);
> kfree_rcu(ht, rcu);
> return 0;
> @@ -989,7 +999,7 @@ static int u32_change(struct net *net, struct sk_buff *in_skb,
>
> err = u32_replace_hw_hnode(tp, ht, userflags, extack);
> if (err) {
> - idr_remove(&tp_c->handle_idr, handle);
> + idr_remove(&tp_c->handle_idr, handle2id(handle));
> kfree(ht);
> return err;
> }
> diff --git a/tools/testing/selftests/tc-testing/tc-tests/filters/u32.json b/tools/testing/selftests/tc-testing/tc-tests/filters/u32.json
> index 24bd0c2a3014..b2ca9d4e991b 100644
> --- a/tools/testing/selftests/tc-testing/tc-tests/filters/u32.json
> +++ b/tools/testing/selftests/tc-testing/tc-tests/filters/u32.json
> @@ -329,5 +329,29 @@
> "teardown": [
> "$TC qdisc del dev $DEV1 parent root drr"
> ]
> + },
> + {
> + "id": "1234",
> + "name": "Exercise IDR leaks by creating/deleting a filter many (2048) times",
> + "category": [
> + "filter",
> + "u32"
> + ],
> + "plugins": {
> + "requires": "nsPlugin"
> + },
> + "setup": [
> + "$TC qdisc add dev $DEV1 parent root handle 10: drr",
> + "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 u32 match ip src 0.0.0.2/32 action drop",
> + "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 3 u32 match ip src 0.0.0.3/32 action drop"
> + ],
> + "cmdUnderTest": "bash -c 'for i in {1..2048} ;do echo filter delete dev $DEV1 pref 3;echo filter add dev $DEV1 parent 10:0 protocol ip prio 3 u32 match ip src 0.0.0.3/32 action drop;done | $TC -b -'",
> + "expExitCode": "0",
> + "verifyCmd": "$TC filter show dev $DEV1",
> + "matchPattern": "protocol ip pref 3 u32",
> + "matchCount": "3",
> + "teardown": [
> + "$TC qdisc del dev $DEV1 parent root drr"
> + ]
> }
> ]
> --
> 2.30.2
>
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