linux.git/net/sched/sch_dualpi2.c, branch master

net/sched: Handle TC_ACT_REDIRECT from qdisc filter chains

2026-07-21T01:16:43Z

When a TC filter attached to a qdisc filter chain returns TC_ACT_REDIRECT (ex: via an eBPF program calling bpf_redirect() or an act_bpf action), the redirect was silently lost i.e no qdisc classify function handled TC_ACT_REDIRECT, so the packet fell through the switch and was enqueued normally instead of being redirected. This has been broken since bpf_redirect() was introduced for TC in commit 27b29f63058d ("bpf: add bpf_redirect() helper"). We got lucky for a long time because bpf_net_context was a per-CPU variable that was always available. commit 401cb7dae813 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.") turned bpf_net_context into a task_struct member that is only set up by explicit callers. Without a caller setting it up, bpf_redirect() itself crashes with a NULL pointer dereference in bpf_net_ctx_get_ri(). However, even with bpf_net_context available, TC_ACT_REDIRECT from qdisc filter chains cannot be honored without adding skb_do_redirect() calls to every qdisc classify function, which would require changes across net/sched/. Isolate it to ebpf core where it belongs. Instead, add a tcf_classify_qdisc() inline helper in pkt_cls.h, as a wrapper around tcf_classify() for use by qdisc classify functions and tcf_qevent_handle(). When the classify verdict is TC_ACT_REDIRECT, the wrapper converts it to TC_ACT_SHOT, dropping the packet rather than letting it continue silently. Dropping is preferred over letting the packet through because the user immediately sees packet loss. Silently passing the packet through would hide the problem and leave the user wondering why their redirect is not working. The clsact fast path, tc_run() continues to call tcf_classify() directly and is unaffected: TC_ACT_REDIRECT is returned as-is and handled by sch_handle_egress/ingress() calling skb_do_redirect() as before. Fixes: 27b29f63058d ("bpf: add bpf_redirect() helper") Fixes: 401cb7dae813 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.") Tested-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Signed-off-by: Daniel Borkmann Reviewed-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/20260706185609.330006-3-daniel@iogearbox.net Signed-off-by: Jakub Kicinski

net/sched: dualpi2: clear stale classification on filter miss

2026-07-01T08:00:25Z

DualPI2 leaves previous classification state attached to an skb when filter classification returns no match. The enqueue path can then act on stale state from an earlier classification attempt. A filter miss should fall back to the default class without reusing old per-packet classification data. Initialize the classification result to CLASSIC before running the classifier. Explicit L4S, priority, and successful filter classification can still override that default. Fixes: 8f9516daedd6 ("sched: Add enqueue/dequeue of dualpi2 qdisc") Assisted-by: Codex:gpt-5.5-cyber-preview Signed-off-by: Samuel Moelius Signed-off-by: David S. Miller

net/sched: dualpi2: fix GSO backlog accounting

2026-06-21T22:16:03Z

When DualPI2 splits a GSO skb into N segments, it propagates N additional packets to its parent before returning NET_XMIT_SUCCESS. The parent then accounts for the original skb once more, leaving its qlen one larger than the number of packets actually queued. With QFQ as the parent, after all real packets are dequeued, QFQ still has a non-zero qlen while its in-service aggregate has no active classes. qfq_choose_next_agg() returns NULL and qfq_dequeue() passes the result to qfq_peek_skb(), causing a NULL pointer dereference. Follow the same pattern used by tbf_segment() and taprio: count only successfully queued segments, propagate the difference between the original skb and those segments, and return NET_XMIT_SUCCESS whenever at least one segment was queued. Fixes: 8f9516daedd6 ("sched: Add enqueue/dequeue of dualpi2 qdisc") Cc: stable@vger.kernel.org Signed-off-by: Xingquan Liu Acked-by: Jamal Hadi Salim Reviewed-by: Victor Nogueira Link: https://patch.msgid.link/20260619151447.223640-1-b1n@b1n.io Signed-off-by: Jakub Kicinski

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2026-06-16T21:59:58Z

Merge in late fixes in preparation for the net-next PR. Conflicts: net/tls/tls_sw.c 406e8a651a7b ("net: skmsg: preserve sg.copy across SG transforms") 79511603a65b ("tls: remove dead sockmap (psock) handling from the SW path") drivers/net/ethernet/microsoft/mana/mana_en.c f8fd56977eeea ("net: mana: guard TX wq object destroy with INVALID_MANA_HANDLE check") d07efe5a6e641 ("net: mana: Use per-queue allocation for tx_qp to reduce allocation size") https://lore.kernel.org/ajAPXu-C_PuTgV-a@sirena.org.uk No adjacent changes. Signed-off-by: Jakub Kicinski

net/sched: sch_dualpi2: Add missing module alias

2026-06-13T00:59:32Z

When a qdisc is added by name, the kernel tries to autoload its module via request_qdisc_module(), which calls: request_module(NET_SCH_ALIAS_PREFIX "%s", name); i.e. it asks modprobe to resolve the "net-sch-" alias (e.g. "net-sch-dualpi2") rather than the module's file name. Since dualpi2 was shipped without this alias, the autoload fails: tc qdisc add dev lo root handle 1: dualpi2 Error: Specified qdisc kind is unknown. Fix this by adding the missing alias so the qdisc is autoloaded on demand like the others. Fixes: 320d031ad6e4 ("sched: Struct definition and parsing of dualpi2 qdisc") Signed-off-by: Victor Nogueira Reviewed-by: Pedro Tammela Link: https://patch.msgid.link/20260611205849.3287640-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski

net/sched: sch_dualpi2: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen

2026-06-13T00:20:53Z

Whenever dualpi2 drops packets during peek, it calls qdisc_tree_reduce_backlog. An issue arises because it calls qdisc_tree_reduce_backlog before it reincrements the qlen. If qlen drops to zero, but peek returns an skb, the parent's qlen_notify callback will be executed even though dualpi2 still has 1 packet on the queue and, thus, mistakenly deactivates the parent's class which leads to a null-ptr-deref: [ 101.427314][ T599] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] SMP KASAN NOPTI [ 101.427755][ T599] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f] [ 101.428048][ T599] CPU: 2 UID: 0 PID: 599 Comm: ping Not tainted 7.1.0-rc5-00284-gbce53c430ed7 #102 PREEMPT(full) [ 101.428400][ T599] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 101.428608][ T599] RIP: 0010:qfq_dequeue (net/sched/sch_qfq.c:1150) sch_qfq [ 101.428821][ T599] Code: 00 fc ff df 80 3c 02 00 0f 85 46 0c 00 00 4c 8d 73 48 48 89 9d b8 02 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 2d 0c 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b All code [ 101.429348][ T599] RSP: 0018:ffff8881110df4f0 EFLAGS: 00010216 [ 101.429541][ T599] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: dffffc0000000000 [ 101.429763][ T599] RDX: 0000000000000009 RSI: 00000024c0000000 RDI: ffff88811436c2b0 [ 101.429985][ T599] RBP: ffff88811436c000 R08: ffff88811436c280 R09: 1ffff11021277523 [ 101.430206][ T599] R10: 1ffff11021277526 R11: 1ffff11021277527 R12: 00000024c0000000 [ 101.430423][ T599] R13: ffff88811436c2b8 R14: 0000000000000048 R15: 0000000020000000 [ 101.430642][ T599] FS: 00007f61813e1c40(0000) GS:ffff8881691ef000(0000) knlGS:0000000000000000 [ 101.430913][ T599] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 101.431100][ T599] CR2: 00005651650850a8 CR3: 000000010ca0b000 CR4: 0000000000750ef0 [ 101.431320][ T599] PKRU: 55555554 [ 101.431433][ T599] Call Trace: [ 101.431544][ T599] [ 101.431628][ T599] __qdisc_run (net/sched/sch_generic.c:322 net/sched/sch_generic.c:427 net/sched/sch_generic.c:445) [ 101.431792][ T599] ? dev_qdisc_enqueue (./include/trace/events/qdisc.h:49 (discriminator 22) net/core/dev.c:4176 (discriminator 22)) [ 101.431941][ T599] __dev_queue_xmit (./include/net/pkt_sched.h:120 ./include/net/pkt_sched.h:117 net/core/dev.c:4292 net/core/dev.c:4831) Fix this by only calling qdisc_tree_reduce_backlog in peek after the qlen is restored. Fixes: 8f9516daedd6 ("sched: Add enqueue/dequeue of dualpi2 qdisc") Acked-by: Jamal Hadi Salim Signed-off-by: Victor Nogueira Link: https://patch.msgid.link/20260610192855.3121513-4-victor@mojatatu.com Signed-off-by: Jakub Kicinski

net/sched: sch_dualpi2: annotate data-races in dualpi2_dump_stats()

2026-05-16T00:43:49Z

dualpi2_dump_stats() runs without qdisc lock held. Add missing READ_ONCE()/WRITE_ONCE() annotations. Fixes: d4de8bffbef4 ("sched: Dump configuration and statistics of dualpi2 qdisc") Signed-off-by: Eric Dumazet Cc: Vineet Agarwal Link: https://patch.msgid.link/20260514114713.4134674-1-edumazet@google.com Signed-off-by: Jakub Kicinski

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2026-05-14T17:08:06Z

Cross-merge networking fixes after downstream PR (net-7.1-rc4). No conflicts, or adjacent changes. Signed-off-by: Jakub Kicinski

net/sched: add qdisc_qlen_inc() and qdisc_qlen_dec()

2026-05-12T01:28:07Z

Helpers to increment or decrement sch->q.qlen, with appropriate WRITE_ONCE() to prevent store tearing. Add other WRITE_ONCE() when sch->q.qlen is changed. Signed-off-by: Eric Dumazet Acked-by: Toke Høiland-Jørgensen Link: https://patch.msgid.link/20260510091455.4039245-3-edumazet@google.com Signed-off-by: Jakub Kicinski

net/sched: dualpi2: initialize timer earlier in dualpi2_init()

2026-05-12T01:03:16Z

'pi2_timer' needs to be initialized in all error paths of dualpi2_init(): otherwise, a failure in qdisc_create_dflt() causes the following crash in dualpi2_destroy(): # tc qdisc add dev crash0 handle 1: root dualpi2 BUG: kernel NULL pointer dereference, address: 0000000000000010 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP PTI CPU: 4 UID: 0 PID: 471 Comm: tc Tainted: G E 7.1.0-rc1-virtme #2 PREEMPT(full) Tainted: [E]=UNSIGNED_MODULE Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 RIP: 0010:hrtimer_active+0x39/0x60 Code: f9 eb 23 0f b6 41 38 3c 01 0f 87 87 64 c0 ff 83 e0 01 75 33 48 39 4a 50 74 28 44 3b 42 10 75 06 48 3b 51 30 74 21 48 8b 51 30 <44> 8b 42 10 41 f6 c0 01 74 cf f3 90 44 8b 42 10 41 f6 c0 01 74 c3 RSP: 0018:ffffd0db80b93620 EFLAGS: 00010282 RAX: ffffffffc0400320 RBX: ffff8cf24a4c86b8 RCX: ffff8cf24a4c86b8 RDX: 0000000000000000 RSI: ffff8cf2429c2ab0 RDI: ffff8cf24a4c86b8 RBP: 00000000fffffff4 R08: 0000000000000003 R09: 0000000000000000 R10: 0000000000000001 R11: ffff8cf24a39c500 R12: ffff8cf24822c000 R13: ffffd0db80b936c0 R14: ffffffffc02cf360 R15: 00000000ffffffff FS: 00007fbc01706580(0000) GS:ffff8cf2dc759000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000010 CR3: 0000000008e02003 CR4: 0000000000172ef0 Call Trace: hrtimer_cancel+0x15/0x40 dualpi2_destroy+0x20/0x40 [sch_dualpi2] qdisc_create+0x230/0x570 tc_modify_qdisc+0x716/0xc10 rtnetlink_rcv_msg+0x188/0x780 netlink_rcv_skb+0xcd/0x150 netlink_unicast+0x1ba/0x290 netlink_sendmsg+0x242/0x4d0 ____sys_sendmsg+0x39e/0x3e0 ___sys_sendmsg+0xe1/0x130 __sys_sendmsg+0xad/0x110 do_syscall_64+0x14f/0xf80 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fbc0188b08e Code: 4d 89 d8 e8 94 bd 00 00 4c 8b 5d f8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 11 c9 c3 0f 1f 80 00 00 00 00 48 8b 45 10 0f 05 c3 83 e2 39 83 fa 08 75 e7 e8 03 ff ff ff 0f 1f 00 f3 0f 1e fa RSP: 002b:00007fff593260e0 EFLAGS: 00000202 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbc0188b08e RDX: 0000000000000000 RSI: 00007fff59326190 RDI: 0000000000000003 RBP: 00007fff593260f0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 000055f06124f260 R13: 0000000069fca043 R14: 000055f061255640 R15: 000055f06124d3f8 Modules linked in: sch_dualpi2(E) CR2: 0000000000000010 [1] https://lore.kernel.org/netdev/2e78e01c504c633ebdff18d041833cf2e079a3a4.1607020450.git.dcaratti@redhat.com/ [2] https://lore.kernel.org/netdev/20200725201707.16909-1-xiyou.wangcong@gmail.com/ v2: - rebased on top of latest net.git Fixes: 320d031ad6e4 ("sched: Struct definition and parsing of dualpi2 qdisc") Signed-off-by: Davide Caratti Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/1faca91179702b31da5d87653e1e036543e32722.1778259798.git.dcaratti@redhat.com Signed-off-by: Jakub Kicinski