Revision tags: v6.6.36, v6.6.35, v6.6.34, v6.6.33, v6.6.32, v6.6.31, v6.6.30, v6.6.29 |
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6d8b2c52 |
| 18-Apr-2024 |
Davide Caratti <dcaratti@redhat.com> |
net/sched: fix false lockdep warning on qdisc root lock
[ Upstream commit af0cb3fa3f9ed258d14abab0152e28a0f9593084 ]
Xiumei and Christoph reported the following lockdep splat, complaining of the qd
net/sched: fix false lockdep warning on qdisc root lock
[ Upstream commit af0cb3fa3f9ed258d14abab0152e28a0f9593084 ]
Xiumei and Christoph reported the following lockdep splat, complaining of the qdisc root lock being taken twice:
============================================ WARNING: possible recursive locking detected 6.7.0-rc3+ #598 Not tainted -------------------------------------------- swapper/2/0 is trying to acquire lock: ffff888177190110 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1560/0x2e70
but task is already holding lock: ffff88811995a110 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1560/0x2e70
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ---- lock(&sch->q.lock); lock(&sch->q.lock);
*** DEADLOCK ***
May be due to missing lock nesting notation
5 locks held by swapper/2/0: #0: ffff888135a09d98 ((&in_dev->mr_ifc_timer)){+.-.}-{0:0}, at: call_timer_fn+0x11a/0x510 #1: ffffffffaaee5260 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x2c0/0x1ed0 #2: ffffffffaaee5200 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x209/0x2e70 #3: ffff88811995a110 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1560/0x2e70 #4: ffffffffaaee5200 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x209/0x2e70
stack backtrace: CPU: 2 PID: 0 Comm: swapper/2 Not tainted 6.7.0-rc3+ #598 Hardware name: Red Hat KVM, BIOS 1.13.0-2.module+el8.3.0+7353+9de0a3cc 04/01/2014 Call Trace: <IRQ> dump_stack_lvl+0x4a/0x80 __lock_acquire+0xfdd/0x3150 lock_acquire+0x1ca/0x540 _raw_spin_lock+0x34/0x80 __dev_queue_xmit+0x1560/0x2e70 tcf_mirred_act+0x82e/0x1260 [act_mirred] tcf_action_exec+0x161/0x480 tcf_classify+0x689/0x1170 prio_enqueue+0x316/0x660 [sch_prio] dev_qdisc_enqueue+0x46/0x220 __dev_queue_xmit+0x1615/0x2e70 ip_finish_output2+0x1218/0x1ed0 __ip_finish_output+0x8b3/0x1350 ip_output+0x163/0x4e0 igmp_ifc_timer_expire+0x44b/0x930 call_timer_fn+0x1a2/0x510 run_timer_softirq+0x54d/0x11a0 __do_softirq+0x1b3/0x88f irq_exit_rcu+0x18f/0x1e0 sysvec_apic_timer_interrupt+0x6f/0x90 </IRQ>
This happens when TC does a mirred egress redirect from the root qdisc of device A to the root qdisc of device B. As long as these two locks aren't protecting the same qdisc, they can be acquired in chain: add a per-qdisc lockdep key to silence false warnings. This dynamic key should safely replace the static key we have in sch_htb: it was added to allow enqueueing to the device "direct qdisc" while still holding the qdisc root lock.
v2: don't use static keys anymore in HTB direct qdiscs (thanks Eric Dumazet)
CC: Maxim Mikityanskiy <maxim@isovalent.com> CC: Xiumei Mu <xmu@redhat.com> Reported-by: Christoph Paasch <cpaasch@apple.com> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/451 Signed-off-by: Davide Caratti <dcaratti@redhat.com> Link: https://lore.kernel.org/r/7dc06d6158f72053cf877a82e2a7a5bd23692faa.1713448007.git.dcaratti@redhat.com Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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Revision tags: v6.6.28, v6.6.27, v6.6.26, v6.6.25, v6.6.24, v6.6.23, v6.6.16, v6.6.15, v6.6.14 |
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9ed46144 |
| 22-Jan-2024 |
Ido Schimmel <idosch@nvidia.com> |
net/sched: flower: Fix chain template offload
[ Upstream commit 32f2a0afa95fae0d1ceec2ff06e0e816939964b8 ]
When a qdisc is deleted from a net device the stack instructs the underlying driver to rem
net/sched: flower: Fix chain template offload
[ Upstream commit 32f2a0afa95fae0d1ceec2ff06e0e816939964b8 ]
When a qdisc is deleted from a net device the stack instructs the underlying driver to remove its flow offload callback from the associated filter block using the 'FLOW_BLOCK_UNBIND' command. The stack then continues to replay the removal of the filters in the block for this driver by iterating over the chains in the block and invoking the 'reoffload' operation of the classifier being used. In turn, the classifier in its 'reoffload' operation prepares and emits a 'FLOW_CLS_DESTROY' command for each filter.
However, the stack does not do the same for chain templates and the underlying driver never receives a 'FLOW_CLS_TMPLT_DESTROY' command when a qdisc is deleted. This results in a memory leak [1] which can be reproduced using [2].
Fix by introducing a 'tmplt_reoffload' operation and have the stack invoke it with the appropriate arguments as part of the replay. Implement the operation in the sole classifier that supports chain templates (flower) by emitting the 'FLOW_CLS_TMPLT_{CREATE,DESTROY}' command based on whether a flow offload callback is being bound to a filter block or being unbound from one.
As far as I can tell, the issue happens since cited commit which reordered tcf_block_offload_unbind() before tcf_block_flush_all_chains() in __tcf_block_put(). The order cannot be reversed as the filter block is expected to be freed after flushing all the chains.
[1] unreferenced object 0xffff888107e28800 (size 2048): comm "tc", pid 1079, jiffies 4294958525 (age 3074.287s) hex dump (first 32 bytes): b1 a6 7c 11 81 88 ff ff e0 5b b3 10 81 88 ff ff ..|......[...... 01 00 00 00 00 00 00 00 e0 aa b0 84 ff ff ff ff ................ backtrace: [<ffffffff81c06a68>] __kmem_cache_alloc_node+0x1e8/0x320 [<ffffffff81ab374e>] __kmalloc+0x4e/0x90 [<ffffffff832aec6d>] mlxsw_sp_acl_ruleset_get+0x34d/0x7a0 [<ffffffff832bc195>] mlxsw_sp_flower_tmplt_create+0x145/0x180 [<ffffffff832b2e1a>] mlxsw_sp_flow_block_cb+0x1ea/0x280 [<ffffffff83a10613>] tc_setup_cb_call+0x183/0x340 [<ffffffff83a9f85a>] fl_tmplt_create+0x3da/0x4c0 [<ffffffff83a22435>] tc_ctl_chain+0xa15/0x1170 [<ffffffff838a863c>] rtnetlink_rcv_msg+0x3cc/0xed0 [<ffffffff83ac87f0>] netlink_rcv_skb+0x170/0x440 [<ffffffff83ac6270>] netlink_unicast+0x540/0x820 [<ffffffff83ac6e28>] netlink_sendmsg+0x8d8/0xda0 [<ffffffff83793def>] ____sys_sendmsg+0x30f/0xa80 [<ffffffff8379d29a>] ___sys_sendmsg+0x13a/0x1e0 [<ffffffff8379d50c>] __sys_sendmsg+0x11c/0x1f0 [<ffffffff843b9ce0>] do_syscall_64+0x40/0xe0 unreferenced object 0xffff88816d2c0400 (size 1024): comm "tc", pid 1079, jiffies 4294958525 (age 3074.287s) hex dump (first 32 bytes): 40 00 00 00 00 00 00 00 57 f6 38 be 00 00 00 00 @.......W.8..... 10 04 2c 6d 81 88 ff ff 10 04 2c 6d 81 88 ff ff ..,m......,m.... backtrace: [<ffffffff81c06a68>] __kmem_cache_alloc_node+0x1e8/0x320 [<ffffffff81ab36c1>] __kmalloc_node+0x51/0x90 [<ffffffff81a8ed96>] kvmalloc_node+0xa6/0x1f0 [<ffffffff82827d03>] bucket_table_alloc.isra.0+0x83/0x460 [<ffffffff82828d2b>] rhashtable_init+0x43b/0x7c0 [<ffffffff832aed48>] mlxsw_sp_acl_ruleset_get+0x428/0x7a0 [<ffffffff832bc195>] mlxsw_sp_flower_tmplt_create+0x145/0x180 [<ffffffff832b2e1a>] mlxsw_sp_flow_block_cb+0x1ea/0x280 [<ffffffff83a10613>] tc_setup_cb_call+0x183/0x340 [<ffffffff83a9f85a>] fl_tmplt_create+0x3da/0x4c0 [<ffffffff83a22435>] tc_ctl_chain+0xa15/0x1170 [<ffffffff838a863c>] rtnetlink_rcv_msg+0x3cc/0xed0 [<ffffffff83ac87f0>] netlink_rcv_skb+0x170/0x440 [<ffffffff83ac6270>] netlink_unicast+0x540/0x820 [<ffffffff83ac6e28>] netlink_sendmsg+0x8d8/0xda0 [<ffffffff83793def>] ____sys_sendmsg+0x30f/0xa80
[2] # tc qdisc add dev swp1 clsact # tc chain add dev swp1 ingress proto ip chain 1 flower dst_ip 0.0.0.0/32 # tc qdisc del dev swp1 clsact # devlink dev reload pci/0000:06:00.0
Fixes: bbf73830cd48 ("net: sched: traverse chains in block with tcf_get_next_chain()") Signed-off-by: Ido Schimmel <idosch@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
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Revision tags: v6.6.13, v6.6.12, v6.6.11, v6.6.10, v6.6.9, v6.6.8, v6.6.7, v6.6.6, v6.6.5, v6.6.4, v6.6.3, v6.6.2, v6.5.11, v6.6.1, v6.5.10, v6.6, v6.5.9, v6.5.8, v6.5.7, v6.5.6, v6.5.5, v6.5.4, v6.5.3, v6.5.2, v6.1.51, v6.5.1, v6.1.50, v6.5, v6.1.49, v6.1.48, v6.1.46, v6.1.45, v6.1.44, v6.1.43 |
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8798481b |
| 28-Jul-2023 |
Pedro Tammela <pctammela@mojatatu.com> |
net/sched: wrap open coded Qdics class filter counter
The 'filter_cnt' counter is used to control a Qdisc class lifetime. Each filter referecing this class by its id will eventually increment/decrem
net/sched: wrap open coded Qdics class filter counter
The 'filter_cnt' counter is used to control a Qdisc class lifetime. Each filter referecing this class by its id will eventually increment/decrement this counter in their respective 'add/update/delete' routines. As these operations are always serialized under rtnl lock, we don't need an atomic type like 'refcount_t'.
It also means that we lose the overflow/underflow checks already present in refcount_t, which are valuable to hunt down bugs where the unsigned counter wraps around as it aids automated tools like syzkaller to scream in such situations.
Wrap the open coded increment/decrement into helper functions and add overflow checks to the operations.
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: Pedro Tammela <pctammela@mojatatu.com> Reviewed-by: Simon Horman <horms@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Revision tags: v6.1.42, v6.1.41, v6.1.40, v6.1.39 |
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e420bed0 |
| 19-Jul-2023 |
Daniel Borkmann <daniel@iogearbox.net> |
bpf: Add fd-based tcx multi-prog infra with link support
This work refactors and adds a lightweight extension ("tcx") to the tc BPF ingress and egress data path side for allowing BPF program managem
bpf: Add fd-based tcx multi-prog infra with link support
This work refactors and adds a lightweight extension ("tcx") to the tc BPF ingress and egress data path side for allowing BPF program management based on fds via bpf() syscall through the newly added generic multi-prog API. The main goal behind this work which we also presented at LPC [0] last year and a recent update at LSF/MM/BPF this year [3] is to support long-awaited BPF link functionality for tc BPF programs, which allows for a model of safe ownership and program detachment.
Given the rise in tc BPF users in cloud native environments, this becomes necessary to avoid hard to debug incidents either through stale leftover programs or 3rd party applications accidentally stepping on each others toes. As a recap, a BPF link represents the attachment of a BPF program to a BPF hook point. The BPF link holds a single reference to keep BPF program alive. Moreover, hook points do not reference a BPF link, only the application's fd or pinning does. A BPF link holds meta-data specific to attachment and implements operations for link creation, (atomic) BPF program update, detachment and introspection. The motivation for BPF links for tc BPF programs is multi-fold, for example:
- From Meta: "It's especially important for applications that are deployed fleet-wide and that don't "control" hosts they are deployed to. If such application crashes and no one notices and does anything about that, BPF program will keep running draining resources or even just, say, dropping packets. We at FB had outages due to such permanent BPF attachment semantics. With fd-based BPF link we are getting a framework, which allows safe, auto-detachable behavior by default, unless application explicitly opts in by pinning the BPF link." [1]
- From Cilium-side the tc BPF programs we attach to host-facing veth devices and phys devices build the core datapath for Kubernetes Pods, and they implement forwarding, load-balancing, policy, EDT-management, etc, within BPF. Currently there is no concept of 'safe' ownership, e.g. we've recently experienced hard-to-debug issues in a user's staging environment where another Kubernetes application using tc BPF attached to the same prio/handle of cls_bpf, accidentally wiping all Cilium-based BPF programs from underneath it. The goal is to establish a clear/safe ownership model via links which cannot accidentally be overridden. [0,2]
BPF links for tc can co-exist with non-link attachments, and the semantics are in line also with XDP links: BPF links cannot replace other BPF links, BPF links cannot replace non-BPF links, non-BPF links cannot replace BPF links and lastly only non-BPF links can replace non-BPF links. In case of Cilium, this would solve mentioned issue of safe ownership model as 3rd party applications would not be able to accidentally wipe Cilium programs, even if they are not BPF link aware.
Earlier attempts [4] have tried to integrate BPF links into core tc machinery to solve cls_bpf, which has been intrusive to the generic tc kernel API with extensions only specific to cls_bpf and suboptimal/complex since cls_bpf could be wiped from the qdisc also. Locking a tc BPF program in place this way, is getting into layering hacks given the two object models are vastly different.
We instead implemented the tcx (tc 'express') layer which is an fd-based tc BPF attach API, so that the BPF link implementation blends in naturally similar to other link types which are fd-based and without the need for changing core tc internal APIs. BPF programs for tc can then be successively migrated from classic cls_bpf to the new tc BPF link without needing to change the program's source code, just the BPF loader mechanics for attaching is sufficient.
For the current tc framework, there is no change in behavior with this change and neither does this change touch on tc core kernel APIs. The gist of this patch is that the ingress and egress hook have a lightweight, qdisc-less extension for BPF to attach its tc BPF programs, in other words, a minimal entry point for tc BPF. The name tcx has been suggested from discussion of earlier revisions of this work as a good fit, and to more easily differ between the classic cls_bpf attachment and the fd-based one.
For the ingress and egress tcx points, the device holds a cache-friendly array with program pointers which is separated from control plane (slow-path) data. Earlier versions of this work used priority to determine ordering and expression of dependencies similar as with classic tc, but it was challenged that for something more future-proof a better user experience is required. Hence this resulted in the design and development of the generic attach/detach/query API for multi-progs. See prior patch with its discussion on the API design. tcx is the first user and later we plan to integrate also others, for example, one candidate is multi-prog support for XDP which would benefit and have the same 'look and feel' from API perspective.
The goal with tcx is to have maximum compatibility to existing tc BPF programs, so they don't need to be rewritten specifically. Compatibility to call into classic tcf_classify() is also provided in order to allow successive migration or both to cleanly co-exist where needed given its all one logical tc layer and the tcx plus classic tc cls/act build one logical overall processing pipeline.
tcx supports the simplified return codes TCX_NEXT which is non-terminating (go to next program) and terminating ones with TCX_PASS, TCX_DROP, TCX_REDIRECT. The fd-based API is behind a static key, so that when unused the code is also not entered. The struct tcx_entry's program array is currently static, but could be made dynamic if necessary at a point in future. The a/b pair swap design has been chosen so that for detachment there are no allocations which otherwise could fail.
The work has been tested with tc-testing selftest suite which all passes, as well as the tc BPF tests from the BPF CI, and also with Cilium's L4LB.
Thanks also to Nikolay Aleksandrov and Martin Lau for in-depth early reviews of this work.
[0] https://lpc.events/event/16/contributions/1353/ [1] https://lore.kernel.org/bpf/CAEf4BzbokCJN33Nw_kg82sO=xppXnKWEncGTWCTB9vGCmLB6pw@mail.gmail.com [2] https://colocatedeventseu2023.sched.com/event/1Jo6O/tales-from-an-ebpf-programs-murder-mystery-hemanth-malla-guillaume-fournier-datadog [3] http://vger.kernel.org/bpfconf2023_material/tcx_meta_netdev_borkmann.pdf [4] https://lore.kernel.org/bpf/20210604063116.234316-1-memxor@gmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Jakub Kicinski <kuba@kernel.org> Link: https://lore.kernel.org/r/20230719140858.13224-3-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Revision tags: v6.1.38, v6.1.37, v6.1.36, v6.4, v6.1.35 |
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e16ad981 |
| 15-Jun-2023 |
YueHaibing <yuehaibing@huawei.com> |
net: sched: Remove unused qdisc_l2t()
This is unused since switch to psched_l2t_ns().
Signed-off-by: YueHaibing <yuehaibing@huawei.com> Reviewed-by: Simon Horman <simon.horman@corigine.com> Link: h
net: sched: Remove unused qdisc_l2t()
This is unused since switch to psched_l2t_ns().
Signed-off-by: YueHaibing <yuehaibing@huawei.com> Reviewed-by: Simon Horman <simon.horman@corigine.com> Link: https://lore.kernel.org/r/20230615124810.34020-1-yuehaibing@huawei.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Revision tags: v6.1.34 |
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84ad0af0 |
| 10-Jun-2023 |
Peilin Ye <peilin.ye@bytedance.com> |
net/sched: qdisc_destroy() old ingress and clsact Qdiscs before grafting
mini_Qdisc_pair::p_miniq is a double pointer to mini_Qdisc, initialized in ingress_init() to point to net_device::miniq_ingre
net/sched: qdisc_destroy() old ingress and clsact Qdiscs before grafting
mini_Qdisc_pair::p_miniq is a double pointer to mini_Qdisc, initialized in ingress_init() to point to net_device::miniq_ingress. ingress Qdiscs access this per-net_device pointer in mini_qdisc_pair_swap(). Similar for clsact Qdiscs and miniq_egress.
Unfortunately, after introducing RTNL-unlocked RTM_{NEW,DEL,GET}TFILTER requests (thanks Hillf Danton for the hint), when replacing ingress or clsact Qdiscs, for example, the old Qdisc ("@old") could access the same miniq_{in,e}gress pointer(s) concurrently with the new Qdisc ("@new"), causing race conditions [1] including a use-after-free bug in mini_qdisc_pair_swap() reported by syzbot:
BUG: KASAN: slab-use-after-free in mini_qdisc_pair_swap+0x1c2/0x1f0 net/sched/sch_generic.c:1573 Write of size 8 at addr ffff888045b31308 by task syz-executor690/14901 ... Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106 print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:319 print_report mm/kasan/report.c:430 [inline] kasan_report+0x11c/0x130 mm/kasan/report.c:536 mini_qdisc_pair_swap+0x1c2/0x1f0 net/sched/sch_generic.c:1573 tcf_chain_head_change_item net/sched/cls_api.c:495 [inline] tcf_chain0_head_change.isra.0+0xb9/0x120 net/sched/cls_api.c:509 tcf_chain_tp_insert net/sched/cls_api.c:1826 [inline] tcf_chain_tp_insert_unique net/sched/cls_api.c:1875 [inline] tc_new_tfilter+0x1de6/0x2290 net/sched/cls_api.c:2266 ...
@old and @new should not affect each other. In other words, @old should never modify miniq_{in,e}gress after @new, and @new should not update @old's RCU state.
Fixing without changing sch_api.c turned out to be difficult (please refer to Closes: for discussions). Instead, make sure @new's first call always happen after @old's last call (in {ingress,clsact}_destroy()) has finished:
In qdisc_graft(), return -EBUSY if @old has any ongoing filter requests, and call qdisc_destroy() for @old before grafting @new.
Introduce qdisc_refcount_dec_if_one() as the counterpart of qdisc_refcount_inc_nz() used for filter requests. Introduce a non-static version of qdisc_destroy() that does a TCQ_F_BUILTIN check, just like qdisc_put() etc.
Depends on patch "net/sched: Refactor qdisc_graft() for ingress and clsact Qdiscs".
[1] To illustrate, the syzkaller reproducer adds ingress Qdiscs under TC_H_ROOT (no longer possible after commit c7cfbd115001 ("net/sched: sch_ingress: Only create under TC_H_INGRESS")) on eth0 that has 8 transmission queues:
Thread 1 creates ingress Qdisc A (containing mini Qdisc a1 and a2), then adds a flower filter X to A.
Thread 2 creates another ingress Qdisc B (containing mini Qdisc b1 and b2) to replace A, then adds a flower filter Y to B.
Thread 1 A's refcnt Thread 2 RTM_NEWQDISC (A, RTNL-locked) qdisc_create(A) 1 qdisc_graft(A) 9
RTM_NEWTFILTER (X, RTNL-unlocked) __tcf_qdisc_find(A) 10 tcf_chain0_head_change(A) mini_qdisc_pair_swap(A) (1st) | | RTM_NEWQDISC (B, RTNL-locked) RCU sync 2 qdisc_graft(B) | 1 notify_and_destroy(A) | tcf_block_release(A) 0 RTM_NEWTFILTER (Y, RTNL-unlocked) qdisc_destroy(A) tcf_chain0_head_change(B) tcf_chain0_head_change_cb_del(A) mini_qdisc_pair_swap(B) (2nd) mini_qdisc_pair_swap(A) (3rd) | ... ...
Here, B calls mini_qdisc_pair_swap(), pointing eth0->miniq_ingress to its mini Qdisc, b1. Then, A calls mini_qdisc_pair_swap() again during ingress_destroy(), setting eth0->miniq_ingress to NULL, so ingress packets on eth0 will not find filter Y in sch_handle_ingress().
This is just one of the possible consequences of concurrently accessing miniq_{in,e}gress pointers.
Fixes: 7a096d579e8e ("net: sched: ingress: set 'unlocked' flag for Qdisc ops") Fixes: 87f373921c4e ("net: sched: ingress: set 'unlocked' flag for clsact Qdisc ops") Reported-by: syzbot+b53a9c0d1ea4ad62da8b@syzkaller.appspotmail.com Closes: https://lore.kernel.org/r/0000000000006cf87705f79acf1a@google.com/ Cc: Hillf Danton <hdanton@sina.com> Cc: Vlad Buslov <vladbu@mellanox.com> Signed-off-by: Peilin Ye <peilin.ye@bytedance.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Revision tags: v6.1.33 |
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#
d636fc5d |
| 06-Jun-2023 |
Eric Dumazet <edumazet@google.com> |
net: sched: add rcu annotations around qdisc->qdisc_sleeping
syzbot reported a race around qdisc->qdisc_sleeping [1]
It is time we add proper annotations to reads and writes to/from qdisc->qdisc_sl
net: sched: add rcu annotations around qdisc->qdisc_sleeping
syzbot reported a race around qdisc->qdisc_sleeping [1]
It is time we add proper annotations to reads and writes to/from qdisc->qdisc_sleeping.
[1] BUG: KCSAN: data-race in dev_graft_qdisc / qdisc_lookup_rcu
read to 0xffff8881286fc618 of 8 bytes by task 6928 on cpu 1: qdisc_lookup_rcu+0x192/0x2c0 net/sched/sch_api.c:331 __tcf_qdisc_find+0x74/0x3c0 net/sched/cls_api.c:1174 tc_get_tfilter+0x18f/0x990 net/sched/cls_api.c:2547 rtnetlink_rcv_msg+0x7af/0x8c0 net/core/rtnetlink.c:6386 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2546 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6413 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline] netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365 netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1913 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg net/socket.c:747 [inline] ____sys_sendmsg+0x375/0x4c0 net/socket.c:2503 ___sys_sendmsg net/socket.c:2557 [inline] __sys_sendmsg+0x1e3/0x270 net/socket.c:2586 __do_sys_sendmsg net/socket.c:2595 [inline] __se_sys_sendmsg net/socket.c:2593 [inline] __x64_sys_sendmsg+0x46/0x50 net/socket.c:2593 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
write to 0xffff8881286fc618 of 8 bytes by task 6912 on cpu 0: dev_graft_qdisc+0x4f/0x80 net/sched/sch_generic.c:1115 qdisc_graft+0x7d0/0xb60 net/sched/sch_api.c:1103 tc_modify_qdisc+0x712/0xf10 net/sched/sch_api.c:1693 rtnetlink_rcv_msg+0x807/0x8c0 net/core/rtnetlink.c:6395 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2546 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6413 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline] netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365 netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1913 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg net/socket.c:747 [inline] ____sys_sendmsg+0x375/0x4c0 net/socket.c:2503 ___sys_sendmsg net/socket.c:2557 [inline] __sys_sendmsg+0x1e3/0x270 net/socket.c:2586 __do_sys_sendmsg net/socket.c:2595 [inline] __se_sys_sendmsg net/socket.c:2593 [inline] __x64_sys_sendmsg+0x46/0x50 net/socket.c:2593 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 6912 Comm: syz-executor.5 Not tainted 6.4.0-rc3-syzkaller-00190-g0d85b27b0cc6 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/16/2023
Fixes: 3a7d0d07a386 ("net: sched: extend Qdisc with rcu") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Vlad Buslov <vladbu@nvidia.com> Acked-by: Jamal Hadi Salim<jhs@mojatatu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Revision tags: v6.1.32, v6.1.31, v6.1.30, v6.1.29, v6.1.28, v6.1.27, v6.1.26, v6.3, v6.1.25, v6.1.24, v6.1.23, v6.1.22, v6.1.21, v6.1.20, v6.1.19, v6.1.18, v6.1.17, v6.1.16, v6.1.15, v6.1.14, v6.1.13, v6.2 |
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#
80cd22c3 |
| 17-Feb-2023 |
Paul Blakey <paulb@nvidia.com> |
net/sched: cls_api: Support hardware miss to tc action
For drivers to support partial offload of a filter's action list, add support for action miss to specify an action instance to continue from in
net/sched: cls_api: Support hardware miss to tc action
For drivers to support partial offload of a filter's action list, add support for action miss to specify an action instance to continue from in sw.
CT action in particular can't be fully offloaded, as new connections need to be handled in software. This imposes other limitations on the actions that can be offloaded together with the CT action, such as packet modifications.
Assign each action on a filter's action list a unique miss_cookie which drivers can then use to fill action_miss part of the tc skb extension. On getting back this miss_cookie, find the action instance with relevant cookie and continue classifying from there.
Signed-off-by: Paul Blakey <paulb@nvidia.com> Reviewed-by: Jiri Pirko <jiri@nvidia.com> Reviewed-by: Simon Horman <simon.horman@corigine.com> Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Revision tags: v6.1.12, v6.1.11, v6.1.10, v6.1.9, v6.1.8, v6.1.7, v6.1.6 |
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#
3a415d59 |
| 13-Jan-2023 |
Eric Dumazet <edumazet@google.com> |
net/sched: sch_taprio: fix possible use-after-free
syzbot reported a nasty crash [1] in net_tx_action() which made little sense until we got a repro.
This repro installs a taprio qdisc, but providi
net/sched: sch_taprio: fix possible use-after-free
syzbot reported a nasty crash [1] in net_tx_action() which made little sense until we got a repro.
This repro installs a taprio qdisc, but providing an invalid TCA_RATE attribute.
qdisc_create() has to destroy the just initialized taprio qdisc, and taprio_destroy() is called.
However, the hrtimer used by taprio had already fired, therefore advance_sched() called __netif_schedule().
Then net_tx_action was trying to use a destroyed qdisc.
We can not undo the __netif_schedule(), so we must wait until one cpu serviced the qdisc before we can proceed.
Many thanks to Alexander Potapenko for his help.
[1] BUG: KMSAN: uninit-value in queued_spin_trylock include/asm-generic/qspinlock.h:94 [inline] BUG: KMSAN: uninit-value in do_raw_spin_trylock include/linux/spinlock.h:191 [inline] BUG: KMSAN: uninit-value in __raw_spin_trylock include/linux/spinlock_api_smp.h:89 [inline] BUG: KMSAN: uninit-value in _raw_spin_trylock+0x92/0xa0 kernel/locking/spinlock.c:138 queued_spin_trylock include/asm-generic/qspinlock.h:94 [inline] do_raw_spin_trylock include/linux/spinlock.h:191 [inline] __raw_spin_trylock include/linux/spinlock_api_smp.h:89 [inline] _raw_spin_trylock+0x92/0xa0 kernel/locking/spinlock.c:138 spin_trylock include/linux/spinlock.h:359 [inline] qdisc_run_begin include/net/sch_generic.h:187 [inline] qdisc_run+0xee/0x540 include/net/pkt_sched.h:125 net_tx_action+0x77c/0x9a0 net/core/dev.c:5086 __do_softirq+0x1cc/0x7fb kernel/softirq.c:571 run_ksoftirqd+0x2c/0x50 kernel/softirq.c:934 smpboot_thread_fn+0x554/0x9f0 kernel/smpboot.c:164 kthread+0x31b/0x430 kernel/kthread.c:376 ret_from_fork+0x1f/0x30
Uninit was created at: slab_post_alloc_hook mm/slab.h:732 [inline] slab_alloc_node mm/slub.c:3258 [inline] __kmalloc_node_track_caller+0x814/0x1250 mm/slub.c:4970 kmalloc_reserve net/core/skbuff.c:358 [inline] __alloc_skb+0x346/0xcf0 net/core/skbuff.c:430 alloc_skb include/linux/skbuff.h:1257 [inline] nlmsg_new include/net/netlink.h:953 [inline] netlink_ack+0x5f3/0x12b0 net/netlink/af_netlink.c:2436 netlink_rcv_skb+0x55d/0x6c0 net/netlink/af_netlink.c:2507 rtnetlink_rcv+0x30/0x40 net/core/rtnetlink.c:6108 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0xf3b/0x1270 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x1288/0x1440 net/netlink/af_netlink.c:1921 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] ____sys_sendmsg+0xabc/0xe90 net/socket.c:2482 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2536 __sys_sendmsg net/socket.c:2565 [inline] __do_sys_sendmsg net/socket.c:2574 [inline] __se_sys_sendmsg net/socket.c:2572 [inline] __x64_sys_sendmsg+0x367/0x540 net/socket.c:2572 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
CPU: 0 PID: 13 Comm: ksoftirqd/0 Not tainted 6.0.0-rc2-syzkaller-47461-gac3859c02d7f #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Fixes: 5a781ccbd19e ("tc: Add support for configuring the taprio scheduler") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Vinicius Costa Gomes <vinicius.gomes@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Revision tags: v6.1.5, v6.0.19, v6.0.18, v6.1.4, v6.1.3, v6.0.17, v6.1.2, v6.0.16, v6.1.1, v6.0.15, v6.0.14, v6.0.13, v6.1, v6.0.12, v6.0.11, v6.0.10, v5.15.80, v6.0.9, v5.15.79, v6.0.8, v5.15.78, v6.0.7, v5.15.77, v5.15.76, v6.0.6, v6.0.5, v5.15.75, v6.0.4, v6.0.3, v6.0.2, v5.15.74, v5.15.73, v6.0.1, v5.15.72, v6.0 |
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#
aac4daa8 |
| 28-Sep-2022 |
Vladimir Oltean <vladimir.oltean@nxp.com> |
net/sched: query offload capabilities through ndo_setup_tc()
When adding optional new features to Qdisc offloads, existing drivers must reject the new configuration until they are coded up to act on
net/sched: query offload capabilities through ndo_setup_tc()
When adding optional new features to Qdisc offloads, existing drivers must reject the new configuration until they are coded up to act on it.
Since modifying all drivers in lockstep with the changes in the Qdisc can create problems of its own, it would be nice if there existed an automatic opt-in mechanism for offloading optional features.
Jakub proposes that we multiplex one more kind of call through ndo_setup_tc(): one where the driver populates a Qdisc-specific capability structure.
First user will be taprio in further changes. Here we are introducing the definitions for the base functionality.
Link: https://patchwork.kernel.org/project/netdevbpf/patch/20220923163310.3192733-3-vladimir.oltean@nxp.com/ Suggested-by: Jakub Kicinski <kuba@kernel.org> Co-developed-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Revision tags: v5.15.71, v5.15.70, v5.15.69 |
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1d14b30b |
| 19-Sep-2022 |
Jamal Hadi Salim <jhs@mojatatu.com> |
net: sched: remove unused tcf_result extension
Added by: commit e5cf1baf92cb ("act_mirred: use TC_ACT_REINSERT when possible") but no longer useful.
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.co
net: sched: remove unused tcf_result extension
Added by: commit e5cf1baf92cb ("act_mirred: use TC_ACT_REINSERT when possible") but no longer useful.
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com> Link: https://lore.kernel.org/r/20220919130627.3551233-1-jhs@mojatatu.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Revision tags: v5.15.68, v5.15.67, v5.15.66, v5.15.65, v5.15.64, v5.15.63 |
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#
44387d17 |
| 24-Aug-2022 |
Zhengchao Shao <shaozhengchao@huawei.com> |
net: sched: remove unnecessary init of qdisc skb head
The memory allocated by using kzallloc_node and kcalloc has been cleared. Therefore, the structure members of the new qdisc are 0. So there's no
net: sched: remove unnecessary init of qdisc skb head
The memory allocated by using kzallloc_node and kcalloc has been cleared. Therefore, the structure members of the new qdisc are 0. So there's no need to explicitly assign a value of 0.
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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c19d893f |
| 23-Aug-2022 |
Zhengchao Shao <shaozhengchao@huawei.com> |
net: sched: delete duplicate cleanup of backlog and qlen
qdisc_reset() is clearing qdisc->q.qlen and qdisc->qstats.backlog _after_ calling qdisc->ops->reset. There is no need to clear them again in
net: sched: delete duplicate cleanup of backlog and qlen
qdisc_reset() is clearing qdisc->q.qlen and qdisc->qstats.backlog _after_ calling qdisc->ops->reset. There is no need to clear them again in the specific reset function.
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> Link: https://lore.kernel.org/r/20220824005231.345727-1-shaozhengchao@huawei.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Revision tags: v5.15.62, v5.15.61, v5.15.60, v5.15.59, v5.19, v5.15.58, v5.15.57, v5.15.56 |
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#
ca0cab11 |
| 18-Jul-2022 |
Davide Caratti <dcaratti@redhat.com> |
net/sched: remove qdisc_root_lock() helper
the last caller has been removed with commit 96f5e66e8a79 ("mac80211: fix aggregation for hardware with ampdu queues"), so it's safe to remove this functio
net/sched: remove qdisc_root_lock() helper
the last caller has been removed with commit 96f5e66e8a79 ("mac80211: fix aggregation for hardware with ampdu queues"), so it's safe to remove this function.
Signed-off-by: Davide Caratti <dcaratti@redhat.com> Link: https://lore.kernel.org/r/703d549e3088367651d92a059743f1be848d74b7.1658133689.git.dcaratti@redhat.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Revision tags: v5.15.55, v5.15.54, v5.15.53, v5.15.52, v5.15.51, v5.15.50, v5.15.49, v5.15.48, v5.15.47, v5.15.46, v5.15.45, v5.15.44 |
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#
2e8728c9 |
| 28-May-2022 |
Guoju Fang <gjfang@linux.alibaba.com> |
net: sched: add barrier to fix packet stuck problem for lockless qdisc
In qdisc_run_end(), the spin_unlock() only has store-release semantic, which guarantees all earlier memory access are visible b
net: sched: add barrier to fix packet stuck problem for lockless qdisc
In qdisc_run_end(), the spin_unlock() only has store-release semantic, which guarantees all earlier memory access are visible before it. But the subsequent test_bit() has no barrier semantics so may be reordered ahead of the spin_unlock(). The store-load reordering may cause a packet stuck problem.
The concurrent operations can be described as below, CPU 0 | CPU 1 qdisc_run_end() | qdisc_run_begin() . | . ----> /* may be reorderd here */ | . | . | . | spin_unlock() | set_bit() | . | smp_mb__after_atomic() ---- test_bit() | spin_trylock() . | .
Consider the following sequence of events: CPU 0 reorder test_bit() ahead and see MISSED = 0 CPU 1 calls set_bit() CPU 1 calls spin_trylock() and return fail CPU 0 executes spin_unlock()
At the end of the sequence, CPU 0 calls spin_unlock() and does nothing because it see MISSED = 0. The skb on CPU 1 has beed enqueued but no one take it, until the next cpu pushing to the qdisc (if ever ...) will notice and dequeue it.
This patch fix this by adding one explicit barrier. As spin_unlock() and test_bit() ordering is a store-load ordering, a full memory barrier smp_mb() is needed here.
Fixes: a90c57f2cedd ("net: sched: fix packet stuck problem for lockless qdisc") Signed-off-by: Guoju Fang <gjfang@linux.alibaba.com> Link: https://lore.kernel.org/r/20220528101628.120193-1-gjfang@linux.alibaba.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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#
a54ce370 |
| 25-May-2022 |
Vincent Ray <vray@kalrayinc.com> |
net: sched: fixed barrier to prevent skbuff sticking in qdisc backlog
In qdisc_run_begin(), smp_mb__before_atomic() used before test_bit() does not provide any ordering guarantee as test_bit() is no
net: sched: fixed barrier to prevent skbuff sticking in qdisc backlog
In qdisc_run_begin(), smp_mb__before_atomic() used before test_bit() does not provide any ordering guarantee as test_bit() is not an atomic operation. This, added to the fact that the spin_trylock() call at the beginning of qdisc_run_begin() does not guarantee acquire semantics if it does not grab the lock, makes it possible for the following statement :
if (test_bit(__QDISC_STATE_MISSED, &qdisc->state))
to be executed before an enqueue operation called before qdisc_run_begin().
As a result the following race can happen :
CPU 1 CPU 2
qdisc_run_begin() qdisc_run_begin() /* true */ set(MISSED) . /* returns false */ . . /* sees MISSED = 1 */ . /* so qdisc not empty */ . __qdisc_run() . . . pfifo_fast_dequeue() ----> /* may be done here */ . | . clear(MISSED) | . . | . smp_mb __after_atomic(); | . . | . /* recheck the queue */ | . /* nothing => exit */ | enqueue(skb1) | . | qdisc_run_begin() | . | spin_trylock() /* fail */ | . | smp_mb__before_atomic() /* not enough */ | . ---- if (test_bit(MISSED)) return false; /* exit */
In the above scenario, CPU 1 and CPU 2 both try to grab the qdisc->seqlock at the same time. Only CPU 2 succeeds and enters the bypass code path, where it emits its skb then calls __qdisc_run().
CPU1 fails, sets MISSED and goes down the traditionnal enqueue() + dequeue() code path. But when executing qdisc_run_begin() for the second time, after enqueuing its skbuff, it sees the MISSED bit still set (by itself) and consequently chooses to exit early without setting it again nor trying to grab the spinlock again.
Meanwhile CPU2 has seen MISSED = 1, cleared it, checked the queue and found it empty, so it returned.
At the end of the sequence, we end up with skb1 enqueued in the backlog, both CPUs out of __dev_xmit_skb(), the MISSED bit not set, and no __netif_schedule() called made. skb1 will now linger in the qdisc until somebody later performs a full __qdisc_run(). Associated to the bypass capacity of the qdisc, and the ability of the TCP layer to avoid resending packets which it knows are still in the qdisc, this can lead to serious traffic "holes" in a TCP connection.
We fix this by replacing the smp_mb__before_atomic() / test_bit() / set_bit() / smp_mb__after_atomic() sequence inside qdisc_run_begin() by a single test_and_set_bit() call, which is more concise and enforces the needed memory barriers.
Fixes: 89837eb4b246 ("net: sched: add barrier to ensure correct ordering for lockless qdisc") Signed-off-by: Vincent Ray <vray@kalrayinc.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20220526001746.2437669-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Revision tags: v5.15.43, v5.15.42, v5.18, v5.15.41, v5.15.40, v5.15.39, v5.15.38, v5.15.37, v5.15.36, v5.15.35, v5.15.34, v5.15.33, v5.15.32, v5.15.31, v5.17, v5.15.30, v5.15.29, v5.15.28, v5.15.27, v5.15.26, v5.15.25, v5.15.24, v5.15.23, v5.15.22, v5.15.21, v5.15.20, v5.15.19, v5.15.18, v5.15.17 |
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#
a459bc9a |
| 26-Jan-2022 |
Jakub Kicinski <kuba@kernel.org> |
net: sched: remove qdisc_qlen_cpu()
Never used since it was added in v5.2.
Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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Revision tags: v5.4.173, v5.15.16, v5.15.15 |
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#
fb80445c |
| 12-Jan-2022 |
Kevin Bracey <kevin@bracey.fi> |
net_sched: restore "mpu xxx" handling
commit 56b765b79e9a ("htb: improved accuracy at high rates") broke "overhead X", "linklayer atm" and "mpu X" attributes.
"overhead X" and "linklayer atm" have
net_sched: restore "mpu xxx" handling
commit 56b765b79e9a ("htb: improved accuracy at high rates") broke "overhead X", "linklayer atm" and "mpu X" attributes.
"overhead X" and "linklayer atm" have already been fixed. This restores the "mpu X" handling, as might be used by DOCSIS or Ethernet shaping:
tc class add ... htb rate X overhead 4 mpu 64
The code being fixed is used by htb, tbf and act_police. Cake has its own mpu handling. qdisc_calculate_pkt_len still uses the size table containing values adjusted for mpu by user space.
iproute2 tc has always passed mpu into the kernel via a tc_ratespec structure, but the kernel never directly acted on it, merely stored it so that it could be read back by `tc class show`.
Rather, tc would generate length-to-time tables that included the mpu (and linklayer) in their construction, and the kernel used those tables.
Since v3.7, the tables were no longer used. Along with "mpu", this also broke "overhead" and "linklayer" which were fixed in 01cb71d2d47b ("net_sched: restore "overhead xxx" handling", v3.10) and 8a8e3d84b171 ("net_sched: restore "linklayer atm" handling", v3.11).
"overhead" was fixed by simply restoring use of tc_ratespec::overhead - this had originally been used by the kernel but was initially omitted from the new non-table-based calculations.
"linklayer" had been handled in the table like "mpu", but the mode was not originally passed in tc_ratespec. The new implementation was made to handle it by getting new versions of tc to pass the mode in an extended tc_ratespec, and for older versions of tc the table contents were analysed at load time to deduce linklayer.
As "mpu" has always been given to the kernel in tc_ratespec, accompanying the mpu-based table, we can restore system functionality with no userspace change by making the kernel act on the tc_ratespec value.
Fixes: 56b765b79e9a ("htb: improved accuracy at high rates") Signed-off-by: Kevin Bracey <kevin@bracey.fi> Cc: Eric Dumazet <edumazet@google.com> Cc: Jiri Pirko <jiri@resnulli.us> Cc: Vimalkumar <j.vimal@gmail.com> Link: https://lore.kernel.org/r/20220112170210.1014351-1-kevin@bracey.fi Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Revision tags: v5.16, v5.15.10, v5.15.9 |
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#
ec624fe7 |
| 14-Dec-2021 |
Paul Blakey <paulb@nvidia.com> |
net/sched: Extend qdisc control block with tc control block
BPF layer extends the qdisc control block via struct bpf_skb_data_end and because of that there is no more room to add variables to the qd
net/sched: Extend qdisc control block with tc control block
BPF layer extends the qdisc control block via struct bpf_skb_data_end and because of that there is no more room to add variables to the qdisc layer control block without going over the skb->cb size.
Extend the qdisc control block with a tc control block, and move all tc related variables to there as a pre-step for extending the tc control block with additional members.
Signed-off-by: Paul Blakey <paulb@nvidia.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Revision tags: v5.15.8, v5.15.7 |
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#
606509f2 |
| 04-Dec-2021 |
Eric Dumazet <edumazet@google.com> |
net/sched: add net device refcount tracker to struct Qdisc
Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Revision tags: v5.15.6, v5.15.5, v5.15.4, v5.15.3, v5.15.2, v5.15.1, v5.15 |
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26746382 |
| 26-Oct-2021 |
Seth Forshee <sforshee@digitalocean.com> |
net: sch: eliminate unnecessary RCU waits in mini_qdisc_pair_swap()
Currently rcu_barrier() is used to ensure that no readers of the inactive mini_Qdisc buffer remain before it is reused. This waits
net: sch: eliminate unnecessary RCU waits in mini_qdisc_pair_swap()
Currently rcu_barrier() is used to ensure that no readers of the inactive mini_Qdisc buffer remain before it is reused. This waits for any pending RCU callbacks to complete, when all that is actually required is to wait for one RCU grace period to elapse after the buffer was made inactive. This means that using rcu_barrier() may result in unnecessary waits.
To improve this, store the current RCU state when a buffer is made inactive and use poll_state_synchronize_rcu() to check whether a full grace period has elapsed before reusing it. If a full grace period has not elapsed, wait for a grace period to elapse, and in the non-RT case use synchronize_rcu_expedited() to hasten it.
Since this approach eliminates the RCU callback it is no longer necessary to synchronize_rcu() in the tp_head==NULL case. However, the RCU state should still be saved for the previously active buffer.
Before this change I would typically see mini_qdisc_pair_swap() take tens of milliseconds to complete. After this change it typcially finishes in less than 1 ms, and often it takes just a few microseconds.
Thanks to Paul for walking me through the options for improving this.
Cc: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Seth Forshee <sforshee@digitalocean.com> Link: https://lore.kernel.org/r/20211026130700.121189-1-seth@forshee.me Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Revision tags: v5.14.14 |
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97604c65 |
| 18-Oct-2021 |
Eric Dumazet <edumazet@google.com> |
net: sched: remove one pair of atomic operations
__QDISC_STATE_RUNNING is only set/cleared from contexts owning qdisc lock.
Thus we can use less expensive bit operations, as we were doing before co
net: sched: remove one pair of atomic operations
__QDISC_STATE_RUNNING is only set/cleared from contexts owning qdisc lock.
Thus we can use less expensive bit operations, as we were doing before commit f9eb8aea2a1e ("net_sched: transform qdisc running bit into a seqcount")
Fixes: 29cbcd858283 ("net: sched: Remove Qdisc::running sequence counter") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Ahmed S. Darwish <a.darwish@linutronix.de> Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Tested-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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4c57e2fa |
| 18-Oct-2021 |
Eric Dumazet <edumazet@google.com> |
net: sched: fix logic error in qdisc_run_begin()
For non TCQ_F_NOLOCK qdisc, qdisc_run_begin() tries to set __QDISC_STATE_RUNNING and should return true if the bit was not set.
test_and_set_bit() r
net: sched: fix logic error in qdisc_run_begin()
For non TCQ_F_NOLOCK qdisc, qdisc_run_begin() tries to set __QDISC_STATE_RUNNING and should return true if the bit was not set.
test_and_set_bit() returns old bit value, therefore we need to invert.
Fixes: 29cbcd858283 ("net: sched: Remove Qdisc::running sequence counter") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Ahmed S. Darwish <a.darwish@linutronix.de> Tested-by: Ido Schimmel <idosch@nvidia.com> Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Tested-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Revision tags: v5.14.13 |
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29cbcd85 |
| 16-Oct-2021 |
Ahmed S. Darwish <a.darwish@linutronix.de> |
net: sched: Remove Qdisc::running sequence counter
The Qdisc::running sequence counter has two uses:
1. Reliably reading qdisc's tc statistics while the qdisc is running (a seqcount read/ret
net: sched: Remove Qdisc::running sequence counter
The Qdisc::running sequence counter has two uses:
1. Reliably reading qdisc's tc statistics while the qdisc is running (a seqcount read/retry loop at gnet_stats_add_basic()).
2. As a flag, indicating whether the qdisc in question is running (without any retry loops).
For the first usage, the Qdisc::running sequence counter write section, qdisc_run_begin() => qdisc_run_end(), covers a much wider area than what is actually needed: the raw qdisc's bstats update. A u64_stats sync point was thus introduced (in previous commits) inside the bstats structure itself. A local u64_stats write section is then started and stopped for the bstats updates.
Use that u64_stats sync point mechanism for the bstats read/retry loop at gnet_stats_add_basic().
For the second qdisc->running usage, a __QDISC_STATE_RUNNING bit flag, accessed with atomic bitops, is sufficient. Using a bit flag instead of a sequence counter at qdisc_run_begin/end() and qdisc_is_running() leads to the SMP barriers implicitly added through raw_read_seqcount() and write_seqcount_begin/end() getting removed. All call sites have been surveyed though, and no required ordering was identified.
Now that the qdisc->running sequence counter is no longer used, remove it.
Note, using u64_stats implies no sequence counter protection for 64-bit architectures. This can lead to the qdisc tc statistics "packets" vs. "bytes" values getting out of sync on rare occasions. The individual values will still be valid.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: David S. Miller <davem@davemloft.net>
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50dc9a85 |
| 16-Oct-2021 |
Ahmed S. Darwish <a.darwish@linutronix.de> |
net: sched: Merge Qdisc::bstats and Qdisc::cpu_bstats data types
The only factor differentiating per-CPU bstats data type (struct gnet_stats_basic_cpu) from the packed non-per-CPU one (struct gnet_s
net: sched: Merge Qdisc::bstats and Qdisc::cpu_bstats data types
The only factor differentiating per-CPU bstats data type (struct gnet_stats_basic_cpu) from the packed non-per-CPU one (struct gnet_stats_basic_packed) was a u64_stats sync point inside the former. The two data types are now equivalent: earlier commits added a u64_stats sync point to the latter.
Combine both data types into "struct gnet_stats_basic_sync". This eliminates redundancy and simplifies the bstats read/write APIs.
Use u64_stats_t for bstats "packets" and "bytes" data types. On 64-bit architectures, u64_stats sync points do not use sequence counter protection.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: David S. Miller <davem@davemloft.net>
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