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path: root/net/sched/bpf_qdisc.c
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2025-07-16bpf: Clean up individual BTF_ID codeFeng Yang
Use BTF_ID_LIST_SINGLE(a, b, c) instead of BTF_ID_LIST(a) BTF_ID(b, c) Signed-off-by: Feng Yang <yangfeng@kylinos.cn> Link: https://lore.kernel.org/r/20250710055419.70544-1-yangfeng59949@163.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-05-02bpf: net_sched: Make some Qdisc_ops ops mandatoryAmery Hung
The patch makes all currently supported Qdisc_ops (i.e., .enqueue, .dequeue, .init, .reset, and .destroy) mandatory. Make .init, .reset and .destroy mandatory as bpf qdisc relies on prologue and epilogue to check attach points and correctly initialize/cleanup resources. The prologue/epilogue will only be generated for an struct_ops operator only if users implement the operator. Make .enqueue and .dequeue mandatory as bpf qdisc infra does not provide a default data path. Fixes: c8240344956e ("bpf: net_sched: Support implementation of Qdisc_ops in bpf") Signed-off-by: Amery Hung <ameryhung@gmail.com> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2025-05-02bpf: net_sched: Fix bpf qdisc init prologue when set as default qdiscAmery Hung
Allow .init to proceed if qdisc_lookup() returns NULL as it only happens when called by qdisc_create_dflt() in mq/mqprio_init and the parent qdisc has not been added to qdisc_hash yet. In qdisc_create(), the caller, __tc_modify_qdisc(), would have made sure the parent qdisc already exist. In addition, call qdisc_watchdog_init() whether .init succeeds or not to prevent null-pointer dereference. In qdisc_create() and qdisc_create_dflt(), if .init fails, .destroy will be called. As a result, the destroy epilogue could call qdisc_watchdog_cancel() with an uninitialized timer, causing null-pointer deference in hrtimer_cancel(). Fixes: c8240344956e ("bpf: net_sched: Support implementation of Qdisc_ops in bpf") Signed-off-by: Amery Hung <ameryhung@gmail.com> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2025-04-17bpf: net_sched: Disable attaching bpf qdisc to non rootAmery Hung
Do not allow users to attach bpf qdiscs to classful qdiscs. This is to prevent accidentally breaking existings classful qdiscs if they rely on some data in the child qdisc. This restriction can potentially be lifted in the future. Note that, we still allow bpf qdisc to be attached to mq. Signed-off-by: Amery Hung <ameryhung@gmail.com> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://patch.msgid.link/20250409214606.2000194-7-ameryhung@gmail.com
2025-04-17bpf: net_sched: Support updating bstatsAmery Hung
Add a kfunc to update Qdisc bstats when an skb is dequeued. The kfunc is only available in .dequeue programs. Signed-off-by: Amery Hung <amery.hung@bytedance.com> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://patch.msgid.link/20250409214606.2000194-6-ameryhung@gmail.com
2025-04-17bpf: net_sched: Add a qdisc watchdog timerAmery Hung
Add a watchdog timer to bpf qdisc. The watchdog can be used to schedule the execution of qdisc through kfunc, bpf_qdisc_schedule(). It can be useful for building traffic shaping scheduling algorithm, where the time the next packet will be dequeued is known. The implementation relies on struct_ops gen_prologue/epilogue to patch bpf programs provided by users. Operator specific prologue/epilogue kfuncs are introduced instead of watchdog kfuncs so that it is easier to extend prologue/epilogue in the future (writing C vs BPF bytecode). Signed-off-by: Amery Hung <amery.hung@bytedance.com> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://patch.msgid.link/20250409214606.2000194-5-ameryhung@gmail.com
2025-04-17bpf: net_sched: Add basic bpf qdisc kfuncsAmery Hung
Add basic kfuncs for working on skb in qdisc. Both bpf_qdisc_skb_drop() and bpf_kfree_skb() can be used to release a reference to an skb. However, bpf_qdisc_skb_drop() can only be called in .enqueue where a to_free skb list is available from kernel to defer the release. bpf_kfree_skb() should be used elsewhere. It is also used in bpf_obj_free_fields() when cleaning up skb in maps and collections. bpf_skb_get_hash() returns the flow hash of an skb, which can be used to build flow-based queueing algorithms. Finally, allow users to create read-only dynptr via bpf_dynptr_from_skb(). Signed-off-by: Amery Hung <amery.hung@bytedance.com> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://patch.msgid.link/20250409214606.2000194-4-ameryhung@gmail.com
2025-04-17bpf: net_sched: Support implementation of Qdisc_ops in bpfAmery Hung
The recent advancement in bpf such as allocated objects, bpf list and bpf rbtree has provided powerful and flexible building blocks to realize sophisticated packet scheduling algorithms. As struct_ops now supports core operators in Qdisc_ops, start allowing qdisc to be implemented using bpf struct_ops with this patch. Users can implement Qdisc_ops.{enqueue, dequeue, init, reset, destroy} in bpf and register the qdisc dynamically into the kernel. Co-developed-by: Cong Wang <cong.wang@bytedance.com> Signed-off-by: Cong Wang <cong.wang@bytedance.com> Signed-off-by: Amery Hung <amery.hung@bytedance.com> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Acked-by: Cong Wang <xiyou.wangcong@gmail.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://patch.msgid.link/20250409214606.2000194-3-ameryhung@gmail.com