kernel/linux.git/net/sched/sch_api.c, branch v7.0-rc1

Convert 'alloc_flex' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This is the exact same thing as the 'alloc_obj()' version, only much smaller because there are a lot fewer users of the *alloc_flex() interface. As with alloc_obj() version, this was done entirely with mindless brute force, using the same script, except using 'flex' in the pattern rather than 'objs*'. Signed-off-by: Linus Torvalds

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

net/sched: don't use dynamic lockdep keys with clsact/ingress/noqueue

2026-02-05T17:32:45+00:00

Currently we are registering one dynamic lockdep key for each allocated qdisc, to avoid false deadlock reports when mirred (or TC eBPF) redirects packets to another device while the root lock is acquired [1]. Since dynamic keys are a limited resource, we can save them at least for qdiscs that are not meant to acquire the root lock in the traffic path, or to carry traffic at all, like: - clsact - ingress - noqueue Don't register dynamic keys for the above schedulers, so that we hit MAX_LOCKDEP_KEYS later in our tests. [1] https://github.com/multipath-tcp/mptcp_net-next/issues/451 Changes in v2: - change ordering of spin_lock_init() vs. lockdep_register_key() (Jakub Kicinski) Signed-off-by: Davide Caratti Link: https://patch.msgid.link/94448f7fa7c4f52d2ce416a4895ec87d456d7417.1770220576.git.dcaratti@redhat.com Signed-off-by: Jakub Kicinski

net/sched: Abort __tc_modify_qdisc if parent is a clsact/ingress qdisc

2025-11-11T00:57:56+00:00

Wang reported an illegal configuration [1] where the user attempts to add a child qdisc to the ingress qdisc as follows: tc qdisc add dev eth0 handle ffff:0 ingress tc qdisc add dev eth0 handle ffe0:0 parent ffff:a fq To solve this, we reject any configuration attempt to add a child qdisc to ingress or clsact. [1] https://lore.kernel.org/netdev/20251105022213.1981982-1-wangliang74@huawei.com/ Fixes: 5e50da01d0ce ("[NET_SCHED]: Fix endless loops (part 2): "simple" qdiscs") Reported-by: Wang Liang Closes: https://lore.kernel.org/netdev/20251105022213.1981982-1-wangliang74@huawei.com/ Reviewed-by: Pedro Tammela Acked-by: Jamal Hadi Salim Signed-off-by: Victor Nogueira Reviewed-by: Cong Wang Link: https://patch.msgid.link/20251106205621.3307639-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski

net/sched: Use TC_RTAB_SIZE instead of magic number

2025-08-15T00:37:48+00:00

Replace magic number with TC_RTAB_SIZE to make it more informative. Signed-off-by: Yue Haibing Link: https://patch.msgid.link/20250813125526.853895-1-yuehaibing@huawei.com Signed-off-by: Jakub Kicinski

net/sched: sch_qfq: Fix null-deref in agg_dequeue

2025-07-10T09:08:35+00:00

To prevent a potential crash in agg_dequeue (net/sched/sch_qfq.c) when cl->qdisc->ops->peek(cl->qdisc) returns NULL, we check the return value before using it, similar to the existing approach in sch_hfsc.c. To avoid code duplication, the following changes are made: 1. Changed qdisc_warn_nonwc(include/net/pkt_sched.h) into a static inline function. 2. Moved qdisc_peek_len from net/sched/sch_hfsc.c to include/net/pkt_sched.h so that sch_qfq can reuse it. 3. Applied qdisc_peek_len in agg_dequeue to avoid crashing. Signed-off-by: Xiang Mei Reviewed-by: Cong Wang Link: https://patch.msgid.link/20250705212143.3982664-1-xmei5@asu.edu Signed-off-by: Paolo Abeni

net/sched: Abort __tc_modify_qdisc if parent class does not exist

2025-07-10T02:23:25+00:00

Lion's patch [1] revealed an ancient bug in the qdisc API. Whenever a user creates/modifies a qdisc specifying as a parent another qdisc, the qdisc API will, during grafting, detect that the user is not trying to attach to a class and reject. However grafting is performed after qdisc_create (and thus the qdiscs' init callback) is executed. In qdiscs that eventually call qdisc_tree_reduce_backlog during init or change (such as fq, hhf, choke, etc), an issue arises. For example, executing the following commands: sudo tc qdisc add dev lo root handle a: htb default 2 sudo tc qdisc add dev lo parent a: handle beef fq Qdiscs such as fq, hhf, choke, etc unconditionally invoke qdisc_tree_reduce_backlog() in their control path init() or change() which then causes a failure to find the child class; however, that does not stop the unconditional invocation of the assumed child qdisc's qlen_notify with a null class. All these qdiscs make the assumption that class is non-null. The solution is ensure that qdisc_leaf() which looks up the parent class, and is invoked prior to qdisc_create(), should return failure on not finding the class. In this patch, we leverage qdisc_leaf to return ERR_PTRs whenever the parentid doesn't correspond to a class, so that we can detect it earlier on and abort before qdisc_create is called. [1] https://lore.kernel.org/netdev/d912cbd7-193b-4269-9857-525bee8bbb6a@gmail.com/ Fixes: 5e50da01d0ce ("[NET_SCHED]: Fix endless loops (part 2): "simple" qdiscs") Reported-by: syzbot+d8b58d7b0ad89a678a16@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/68663c93.a70a0220.5d25f.0857.GAE@google.com/ Reported-by: syzbot+5eccb463fa89309d8bdc@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/68663c94.a70a0220.5d25f.0858.GAE@google.com/ Reported-by: syzbot+1261670bbdefc5485a06@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/686764a5.a00a0220.c7b3.0013.GAE@google.com/ Reported-by: syzbot+15b96fc3aac35468fe77@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/686764a5.a00a0220.c7b3.0014.GAE@google.com/ Reported-by: syzbot+4dadc5aecf80324d5a51@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/68679e81.a70a0220.29cf51.0016.GAE@google.com/ Acked-by: Jamal Hadi Salim Reviewed-by: Cong Wang Signed-off-by: Victor Nogueira Link: https://patch.msgid.link/20250707210801.372995-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski

net/sched: Always pass notifications when child class becomes empty

2025-07-02T21:42:17+00:00

Certain classful qdiscs may invoke their classes' dequeue handler on an enqueue operation. This may unexpectedly empty the child qdisc and thus make an in-flight class passive via qlen_notify(). Most qdiscs do not expect such behaviour at this point in time and may re-activate the class eventually anyways which will lead to a use-after-free. The referenced fix commit attempted to fix this behavior for the HFSC case by moving the backlog accounting around, though this turned out to be incomplete since the parent's parent may run into the issue too. The following reproducer demonstrates this use-after-free: tc qdisc add dev lo root handle 1: drr tc filter add dev lo parent 1: basic classid 1:1 tc class add dev lo parent 1: classid 1:1 drr tc qdisc add dev lo parent 1:1 handle 2: hfsc def 1 tc class add dev lo parent 2: classid 2:1 hfsc rt m1 8 d 1 m2 0 tc qdisc add dev lo parent 2:1 handle 3: netem tc qdisc add dev lo parent 3:1 handle 4: blackhole echo 1 | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888 tc class delete dev lo classid 1:1 echo 1 | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888 Since backlog accounting issues leading to a use-after-frees on stale class pointers is a recurring pattern at this point, this patch takes a different approach. Instead of trying to fix the accounting, the patch ensures that qdisc_tree_reduce_backlog always calls qlen_notify when the child qdisc is empty. This solves the problem because deletion of qdiscs always involves a call to qdisc_reset() and / or qdisc_purge_queue() which ultimately resets its qlen to 0 thus causing the following qdisc_tree_reduce_backlog() to report to the parent. Note that this may call qlen_notify on passive classes multiple times. This is not a problem after the recent patch series that made all the classful qdiscs qlen_notify() handlers idempotent. Fixes: 3f981138109f ("sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue()") Signed-off-by: Lion Ackermann Reviewed-by: Jamal Hadi Salim Acked-by: Cong Wang Acked-by: Jamal Hadi Salim Link: https://patch.msgid.link/d912cbd7-193b-4269-9857-525bee8bbb6a@gmail.com Signed-off-by: Jakub Kicinski

bpf: net_sched: Fix using bpf qdisc as default qdisc

2025-04-29T21:25:41+00:00

Use bpf_try_module_get()/bpf_module_put() instead of try_module_get()/ module_put() when handling default qdisc since users can assign a bpf qdisc to it. To trigger the bug: $ bpftool struct_ops register bpf_qdisc_fq.bpf.o /sys/fs/bpf $ echo bpf_fq > /proc/sys/net/core/default_qdisc Fixes: c8240344956e ("bpf: net_sched: Support implementation of Qdisc_ops in bpf") Signed-off-by: Amery Hung Signed-off-by: Martin KaFai Lau Link: https://patch.msgid.link/20250429192128.3860571-1-ameryhung@gmail.com