kernel.git/net/sched/sch_api.c, branch linux-4.15.y

net, sched: fix panic when updating miniq {b,q}stats

2018-01-16T20:02:36Z

While working on fixing another bug, I ran into the following panic on arm64 by simply attaching clsact qdisc, adding a filter and running traffic on ingress to it: [...] [ 178.188591] Unable to handle kernel read from unreadable memory at virtual address 810fb501f000 [ 178.197314] Mem abort info: [ 178.200121] ESR = 0x96000004 [ 178.203168] Exception class = DABT (current EL), IL = 32 bits [ 178.209095] SET = 0, FnV = 0 [ 178.212157] EA = 0, S1PTW = 0 [ 178.215288] Data abort info: [ 178.218175] ISV = 0, ISS = 0x00000004 [ 178.222019] CM = 0, WnR = 0 [ 178.224997] user pgtable: 4k pages, 48-bit VAs, pgd = 0000000023cb3f33 [ 178.231531] [0000810fb501f000] *pgd=0000000000000000 [ 178.236508] Internal error: Oops: 96000004 [#1] SMP [...] [ 178.311855] CPU: 73 PID: 2497 Comm: ping Tainted: G W 4.15.0-rc7+ #5 [ 178.319413] Hardware name: FOXCONN R2-1221R-A4/C2U4N_MB, BIOS G31FB18A 03/31/2017 [ 178.326887] pstate: 60400005 (nZCv daif +PAN -UAO) [ 178.331685] pc : __netif_receive_skb_core+0x49c/0xac8 [ 178.336728] lr : __netif_receive_skb+0x28/0x78 [ 178.341161] sp : ffff00002344b750 [ 178.344465] x29: ffff00002344b750 x28: ffff810fbdfd0580 [ 178.349769] x27: 0000000000000000 x26: ffff000009378000 [...] [ 178.418715] x1 : 0000000000000054 x0 : 0000000000000000 [ 178.424020] Process ping (pid: 2497, stack limit = 0x000000009f0a3ff4) [ 178.430537] Call trace: [ 178.432976] __netif_receive_skb_core+0x49c/0xac8 [ 178.437670] __netif_receive_skb+0x28/0x78 [ 178.441757] process_backlog+0x9c/0x160 [ 178.445584] net_rx_action+0x2f8/0x3f0 [...] Reason is that sch_ingress and sch_clsact are doing mini_qdisc_pair_init() which sets up miniq pointers to cpu_{b,q}stats from the underlying qdisc. Problem is that this cannot work since they are actually set up right after the qdisc ->init() callback in qdisc_create(), so first packet going into sch_handle_ingress() tries to call mini_qdisc_bstats_cpu_update() and we therefore panic. In order to fix this, allocation of {b,q}stats needs to happen before we call into ->init(). In net-next, there's already such option through commit d59f5ffa59d8 ("net: sched: a dflt qdisc may be used with per cpu stats"). However, the bug needs to be fixed in net still for 4.15. Thus, include these bits to reduce any merge churn and reuse the static_flags field to set TCQ_F_CPUSTATS, and remove the allocation from qdisc_create() since there is no other user left. Prashant Bhole ran into the same issue but for net-next, thus adding him below as well as co-author. Same issue was also reported by Sandipan Das when using bcc. Fixes: 46209401f8f6 ("net: core: introduce mini_Qdisc and eliminate usage of tp->q for clsact fastpath") Reference: https://lists.iovisor.org/pipermail/iovisor-dev/2018-January/001190.html Reported-by: Sandipan Das Co-authored-by: Prashant Bhole Co-authored-by: John Fastabend Signed-off-by: Daniel Borkmann Cc: Jiri Pirko Signed-off-by: David S. Miller

net: sched: Add TCA_HW_OFFLOAD

2017-12-15T18:35:36Z

Qdiscs can be offloaded to HW, but current implementation isn't uniform. Instead, qdiscs either pass information about offload status via their TCA_OPTIONS or omit it altogether. Introduce a new attribute - TCA_HW_OFFLOAD that would form a uniform uAPI for the offloading status of qdiscs. Signed-off-by: Yuval Mintz Acked-by: Jiri Pirko Signed-off-by: David S. Miller

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

2017-10-30T12:09:24Z

Several conflicts here. NFP driver bug fix adding nfp_netdev_is_nfp_repr() check to nfp_fl_output() needed some adjustments because the code block is in an else block now. Parallel additions to net/pkt_cls.h and net/sch_generic.h A bug fix in __tcp_retransmit_skb() conflicted with some of the rbtree changes in net-next. The tc action RCU callback fixes in 'net' had some overlap with some of the recent tcf_block reworking. Signed-off-by: David S. Miller

net_sched: avoid matching qdisc with zero handle

2017-10-29T08:55:03Z

Davide found the following script triggers a NULL pointer dereference: ip l a name eth0 type dummy tc q a dev eth0 parent :1 handle 1: htb This is because for a freshly created netdevice noop_qdisc is attached and when passing 'parent :1', kernel actually tries to match the major handle which is 0 and noop_qdisc has handle 0 so is matched by mistake. Commit 69012ae425d7 tries to fix a similar bug but still misses this case. Handle 0 is not a valid one, should be just skipped. In fact, kernel uses it as TC_H_UNSPEC. Fixes: 69012ae425d7 ("net: sched: fix handling of singleton qdiscs with qdisc_hash") Fixes: 59cc1f61f09c ("net: sched:convert qdisc linked list to hashtable") Reported-by: Davide Caratti Cc: Jiri Kosina Cc: Eric Dumazet Cc: Jamal Hadi Salim Signed-off-by: Cong Wang Signed-off-by: David S. Miller

net: sched: use tcf_block_q helper to get q pointer for sch_tree_lock

2017-10-16T20:00:41Z

Use tcf_block_q helper to get q pointer to be used for direct call of sch_tree_lock/unlock instead of tcf_tree_lock/unlock. Signed-off-by: Jiri Pirko Signed-off-by: David S. Miller

net_sched: use explicit size of struct tcmsg, remove need to declare tcm

2017-09-18T23:52:26Z

Pointer tcm is being initialized and is never read, it is only being used to determine the size of struct tcmsg. Clean this up by removing variable tcm and explicitly using the sizeof struct tcmsg rather than *tcm. Cleans up clang warning: warning: Value stored to 'tcm' during its initialization is never read Signed-off-by: Colin Ian King Signed-off-by: David S. Miller

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

2017-09-02T00:42:05Z

Three cases of simple overlapping changes. Signed-off-by: David S. Miller

net_sched: add reverse binding for tc class

2017-08-31T18:40:52Z

TC filters when used as classifiers are bound to TC classes. However, there is a hidden difference when adding them in different orders: 1. If we add tc classes before its filters, everything is fine. Logically, the classes exist before we specify their ID's in filters, it is easy to bind them together, just as in the current code base. 2. If we add tc filters before the tc classes they bind, we have to do dynamic lookup in fast path. What's worse, this happens all the time not just once, because on fast path tcf_result is passed on stack, there is no way to propagate back to the one in tc filters. This hidden difference hurts performance silently if we have many tc classes in hierarchy. This patch intends to close this gap by doing the reverse binding when we create a new class, in this case we can actually search all the filters in its parent, match and fixup by classid. And because tcf_result is specific to each type of tc filter, we have to introduce a new ops for each filter to tell how to bind the class. Note, we still can NOT totally get rid of those class lookup in ->enqueue() because cgroup and flow filters have no way to determine the classid at setup time, they still have to go through dynamic lookup. Cc: Jamal Hadi Salim Signed-off-by: Cong Wang Signed-off-by: David S. Miller

net_sched: remove tc class reference counting

2017-08-26T00:19:10Z

For TC classes, their ->get() and ->put() are always paired, and the reference counting is completely useless, because: 1) For class modification and dumping paths, we already hold RTNL lock, so all of these ->get(),->change(),->put() are atomic. 2) For filter bindiing/unbinding, we use other reference counter than this one, and they should have RTNL lock too. 3) For ->qlen_notify(), it is special because it is called on ->enqueue() path, but we already hold qdisc tree lock there, and we hold this tree lock when graft or delete the class too, so it should not be gone or changed until we release the tree lock. Therefore, this patch removes ->get() and ->put(), but: 1) Adds a new ->find() to find the pointer to a class by classid, no refcnt. 2) Move the original class destroy upon the last refcnt into ->delete(), right after releasing tree lock. This is fine because the class is already removed from hash when holding the lock. For those who also use ->put() as ->unbind(), just rename them to reflect this change. Cc: Jamal Hadi Salim Signed-off-by: Cong Wang Acked-by: Jiri Pirko Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller

net_sched: introduce tclass_del_notify()

2017-08-26T00:19:10Z

Like for TC actions, ->delete() is a special case, we have to prepare and fill the notification before delete otherwise would get use-after-free after we remove the reference count. Signed-off-by: Cong Wang Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller