net sched rcu updates
Subsystems (6)
John Fastabend
reviewercover net sched rcu updates
This fixes the use of tcf_proto from RCU callbacks it requires moving the unbind calls out of the callbacks and removing the tcf_proto argument from the tcf_em_tree_destroy().
This is a rework of two previous series and addresses comments from Cong. And should apply against latest net-next.
The previous series links below for reference:
(1/2) net: sched: do not use tcf_proto 'tp' argument from call_rcu
http://patchwork.ozlabs.org/patch/396149/
(2/2) net: sched: replace ematch calls to use struct net
http://patchwork.ozlabs.org/patch/396150/
net: sched: cls_cgroup tear down exts and ematch from rcu callback
http://patchwork.ozlabs.org/patch/396307/
---
John Fastabend (3):
net: sched: remove tcf_proto from ematch calls
net: sched: cls_cgroup tear down exts and ematch from rcu callback
net: sched: do not use tcf_proto 'tp' argument from call_rcu
include/net/pkt_cls.h | 10 +++++----- net/sched/cls_basic.c | 7 ++++--- net/sched/cls_bpf.c | 4 +++- net/sched/cls_cgroup.c | 6 ++---- net/sched/cls_flow.c | 4 ++-- net/sched/cls_fw.c | 5 +++-- net/sched/cls_route.c | 8 +++++--- net/sched/em_canid.c | 4 ++-- net/sched/em_ipset.c | 7 +++---- net/sched/em_meta.c | 4 ++-- net/sched/em_nbyte.c | 2 +- net/sched/em_text.c | 4 ++-- net/sched/ematch.c | 10 ++++++---- 13 files changed, 40 insertions(+), 35 deletions(-)
Signature · 1 line
Signature
John Fastabend
reviewerPATCH 1/3 net: sched: remove tcf_proto from ematch calls
This removes the tcf_proto argument from the ematch code paths that only need it to reference the net namespace. This allows simplifying qdisc code paths especially when we need to tear down the ematch from an RCU callback. In this case we can not guarentee that the tcf_proto structure is still valid.
--- include/net/pkt_cls.h | 10 +++++----- net/sched/cls_basic.c | 2 +- net/sched/cls_cgroup.c | 4 ++-- net/sched/cls_flow.c | 4 ++-- net/sched/em_canid.c | 4 ++-- net/sched/em_ipset.c | 7 +++---- net/sched/em_meta.c | 4 ++-- net/sched/em_nbyte.c | 2 +- net/sched/em_text.c | 4 ++-- net/sched/ematch.c | 10 ++++++---- 10 files changed, 26 insertions(+), 25 deletions(-)
include/net/pkt_cls.h +5 -5
@@ -166,6 +166,7 @@ struct tcf_ematch {unsigned int datalen;u16 matchid;u16 flags; +struct net *net; };static inline int tcf_em_is_container (struct tcf_ematch *em)
@@ -229,12 +230,11 @@ struct tcf_ematch_tree {struct tcf_ematch_ops {int kind;int datalen; -int (*change)(struct tcf_proto *,void *, +int (*change)(struct net *net,void *,int ,struct tcf_ematch *);int (*match)(struct sk_buff *,struct tcf_ematch *,struct tcf_pkt_info *); -void (*destroy)(struct tcf_proto *, -struct tcf_ematch *); +void (*destroy)(struct tcf_ematch *);int (*dump)(struct sk_buff *,struct tcf_ematch *);struct module *owner;struct list_head link;
@@ -244,7 +244,7 @@ int tcf_em_register(struct tcf_ematch_ops *);void tcf_em_unregister (struct tcf_ematch_ops *);int tcf_em_tree_validate (struct tcf_proto *,struct nlattr *,struct tcf_ematch_tree *); -void tcf_em_tree_destroy (struct tcf_proto *,struct tcf_ematch_tree *); +void tcf_em_tree_destroy (struct tcf_ematch_tree *);int tcf_em_tree_dump (struct sk_buff *,struct tcf_ematch_tree *,int );int __tcf_em_tree_match (struct sk_buff *,struct tcf_ematch_tree *,struct tcf_pkt_info *);
@@ -301,7 +301,7 @@ struct tcf_ematch_tree { };#define tcf_em_tree_validate (tp, tb, t) ((void)(t), 0) -#define tcf_em_tree_destroy (tp, t) do { (void)(t); } while(0) +#define tcf_em_tree_destroy (t) do { (void)(t); } while(0)#define tcf_em_tree_dump (skb, t, tlv) (0)#define tcf_em_tree_change (tp, dst, src) do { } while(0)#define tcf_em_tree_match (skb, t, info) ((void)(info), 1)
net/sched/cls_basic.c +1 -1
@@ -95,7 +95,7 @@ static void basic_delete_filter(struct rcu_head *head)tcf_unbind_filter (tp, &f->res);tcf_exts_destroy (&f->exts); -tcf_em_tree_destroy (tp, &f->ematches); +tcf_em_tree_destroy (&f->ematches);kfree (f); }
net/sched/cls_cgroup.c +2 -2
@@ -87,7 +87,7 @@ static void cls_cgroup_destroy_rcu(struct rcu_head *root) rcu);tcf_exts_destroy (&head->exts); -tcf_em_tree_destroy (head->tp, &head->ematches); +tcf_em_tree_destroy (&head->ematches);kfree (head); }
@@ -157,7 +157,7 @@ static void cls_cgroup_destroy(struct tcf_proto *tp)if (head) {tcf_exts_destroy (&head->exts); -tcf_em_tree_destroy (tp, &head->ematches); +tcf_em_tree_destroy (&head->ematches);RCU_INIT_POINTER (tp->root,NULL );kfree_rcu (head, rcu); }
net/sched/cls_flow.c +2 -2
@@ -355,7 +355,7 @@ static void flow_destroy_filter(struct rcu_head *head)del_timer_sync (&f->perturb_timer);tcf_exts_destroy (&f->exts); -tcf_em_tree_destroy (f->tp, &f->ematches); +tcf_em_tree_destroy (&f->ematches);kfree (f); }
@@ -530,7 +530,7 @@ static int flow_change(struct net *net, struct sk_buff *in_skb,return 0 ; err2: -tcf_em_tree_destroy (tp, &t); +tcf_em_tree_destroy (&t);kfree (fnew); err1:tcf_exts_destroy (&e);
net/sched/em_canid.c +2 -2
@@ -120,7 +120,7 @@ static int em_canid_match(struct sk_buff *skb, struct tcf_ematch *m,return match; } -static int em_canid_change (struct tcf_proto *tp,void *data,int len, +static int em_canid_change (struct net *net,void *data,int len,struct tcf_ematch *m) {struct can_filter *conf = data;/* Array with rules */
@@ -183,7 +183,7 @@ static int em_canid_change(struct tcf_proto *tp, void *data, int len,return 0 ; } -static void em_canid_destroy (struct tcf_proto *tp,struct tcf_ematch *m) +static void em_canid_destroy (struct tcf_ematch *m) {struct canid_match *cm =em_canid_priv (m);
net/sched/em_ipset.c +3 -4
@@ -19,12 +19,11 @@#include <net/ip.h> #include <net/pkt_cls.h> -static int em_ipset_change (struct tcf_proto *tp,void *data,int data_len, +static int em_ipset_change (struct net *net,void *data,int data_len,struct tcf_ematch *em) {struct xt_set_info *set = data;ip_set_id_t index; -struct net *net =dev_net (qdisc_dev (tp->q));if (data_len !=sizeof (*set))return -EINVAL ;
@@ -42,11 +41,11 @@ static int em_ipset_change(struct tcf_proto *tp, void *data, int data_len,return -ENOMEM ; } -static void em_ipset_destroy (struct tcf_proto *p,struct tcf_ematch *em) +static void em_ipset_destroy (struct tcf_ematch *em) {const struct xt_set_info *set = (const void *) em->data;if (set) { -ip_set_nfnl_put (dev_net (qdisc_dev (p->q)), set->index); +ip_set_nfnl_put (em->net, set->index);kfree ((void *) em->data); } }
net/sched/em_meta.c +2 -2
@@ -856,7 +856,7 @@ static const struct nla_policy meta_policy[TCA_EM_META_MAX + 1] = { [TCA_EM_META_HDR] = { .len = sizeof(struct tcf_meta_hdr) }, }; -static int em_meta_change (struct tcf_proto *tp,void *data,int len, +static int em_meta_change (struct net *net,void *data,int len,struct tcf_ematch *m) {int err;
@@ -908,7 +908,7 @@ errout:return err; } -static void em_meta_destroy (struct tcf_proto *tp,struct tcf_ematch *m) +static void em_meta_destroy (struct tcf_ematch *m) {if (m)meta_delete ((struct meta_match *) m->data);
net/sched/em_nbyte.c +1 -1
@@ -23,7 +23,7 @@ struct nbyte_data {char pattern[0 ]; }; -static int em_nbyte_change (struct tcf_proto *tp,void *data,int data_len, +static int em_nbyte_change (struct net *net,void *data,int data_len,struct tcf_ematch *em) {struct tcf_em_nbyte *nbyte = data;
net/sched/em_text.c +2 -2
@@ -45,7 +45,7 @@ static int em_text_match(struct sk_buff *skb, struct tcf_ematch *m,return skb_find_text (skb, from, to, tm->config, &state) !=UINT_MAX ; } -static int em_text_change (struct tcf_proto *tp,void *data,int len, +static int em_text_change (struct net *net,void *data,int len,struct tcf_ematch *m) {struct text_match *tm;
@@ -100,7 +100,7 @@ retry:return 0 ; } -static void em_text_destroy (struct tcf_proto *tp,struct tcf_ematch *m) +static void em_text_destroy (struct tcf_ematch *m) {if (EM_TEXT_PRIV (m) &&EM_TEXT_PRIV (m)->config)textsearch_destroy (EM_TEXT_PRIV (m)->config);
net/sched/ematch.c +6 -4
@@ -178,6 +178,7 @@ static int tcf_em_validate(struct tcf_proto *tp,struct tcf_ematch_hdr *em_hdr =nla_data (nla);int data_len =nla_len (nla) -sizeof (*em_hdr);void *data = (void *) em_hdr +sizeof (*em_hdr); +struct net *net =dev_net (qdisc_dev (tp->q));if (!TCF_EM_REL_VALID (em_hdr->flags)) goto errout;
@@ -240,7 +241,7 @@ static int tcf_em_validate(struct tcf_proto *tp, goto errout;if (em->ops->change) { - err = em->ops->change (tp, data, data_len, em); + err = em->ops->change (net, data, data_len, em);if (err <0 ) goto errout; }else if (data_len >0 ) {
@@ -271,6 +272,7 @@ static int tcf_em_validate(struct tcf_proto *tp, em->matchid = em_hdr->matchid; em->flags = em_hdr->flags; em->datalen = data_len; + em->net = net; err =0 ; errout:
@@ -378,7 +380,7 @@ errout:return err; errout_abort: -tcf_em_tree_destroy (tp, tree); +tcf_em_tree_destroy (tree);return err; }EXPORT_SYMBOL (tcf_em_tree_validate);
@@ -393,7 +395,7 @@ EXPORT_SYMBOL(tcf_em_tree_validate);* tcf_em_tree_validate()/tcf_em_tree_change(). You must ensure that * the ematch tree is not in use before calling this function. */ -void tcf_em_tree_destroy (struct tcf_proto *tp,struct tcf_ematch_tree *tree) +void tcf_em_tree_destroy (struct tcf_ematch_tree *tree) {int i;
@@ -405,7 +407,7 @@ void tcf_em_tree_destroy(struct tcf_proto *tp, struct tcf_ematch_tree *tree)if (em->ops) {if (em->ops->destroy) - em->ops->destroy (tp, em); + em->ops->destroy (em);else if (!tcf_em_is_simple (em))kfree ((void *) em->data);module_put (em->ops->owner);
Re: [net-next PATCH v1 1/3] net: sched: remove tcf_proto from ematch calls
Quoted 7 lines · John Fastabend
This removes the
tcf_protoargument from the ematch code paths that only need it to reference the net namespace. This allows simplifying qdisc code paths especially when we need to tear down the ematch from an RCU callback. In this case we can not guarentee that thetcf_protostructure is still valid.Signed-off-by John Fastabend <[email protected]>
The code looks cleaner now. :)
John Fastabend
reviewerPATCH 2/3 net: sched: cls_cgroup tear down exts and ematch from rcu callback
In reply to John FastabendIt is not RCU safe to destroy the action chain while there is a possibility of readers accessing it. Move this code into the rcu callback using the same rcu callback used in the code patch to make a change to head.
--- net/sched/cls_cgroup.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
net/sched/cls_cgroup.c +1 -3
@@ -156,10 +156,8 @@ static void cls_cgroup_destroy(struct tcf_proto *tp)struct cls_cgroup_head *head =rtnl_dereference (tp->root);if (head) { -tcf_exts_destroy (&head->exts); -tcf_em_tree_destroy (&head->ematches);RCU_INIT_POINTER (tp->root,NULL ); -kfree_rcu (head, rcu); +call_rcu (&head->rcu, cls_cgroup_destroy_rcu); } }
Re: [net-next PATCH v1 2/3] net: sched: cls_cgroup tear down exts and ematch from rcu callback
Quoted 6 lines · John Fastabend
It is not RCU safe to destroy the action chain while there is a possibility of readers accessing it. Move this code into the rcu callback using the same rcu callback used in the code patch to make a change to head.
Signed-off-by John Fastabend <[email protected]>
John Fastabend
reviewerPATCH 3/3 net: sched: do not use tcf_proto 'tp' argument from call_rcu
In reply to John FastabendUsing the tcf_proto pointer 'tp' from inside the classifiers callback is not valid because it may have been cleaned up by another call_rcu occuring on another CPU.
'tp' is currently being used by tcf_unbind_filter() in this patch we move instances of tcf_unbind_filter outside of the call_rcu() context. This is safe to do because any running schedulers will either read the valid class field or it will be zeroed.
And all schedulers today when the class is 0 do a lookup using the same call used by the tcf_exts_bind(). So even if we have a running classifier hit the null class pointer it will do a lookup and get to the same result. This is particularly fragile at the moment because the only way to verify this is to audit the schedulers call sites.
--- net/sched/cls_basic.c | 5 +++-- net/sched/cls_bpf.c | 4 +++- net/sched/cls_fw.c | 5 +++-- net/sched/cls_route.c | 8 +++++--- 4 files changed, 14 insertions(+), 8 deletions(-)
net/sched/cls_basic.c +3 -2
@@ -91,9 +91,7 @@ static int basic_init(struct tcf_proto *tp)static void basic_delete_filter (struct rcu_head *head) { struct basic_filter *f = container_of(head, struct basic_filter, rcu); -struct tcf_proto *tp = f->tp; -tcf_unbind_filter (tp, &f->res);tcf_exts_destroy (&f->exts);tcf_em_tree_destroy (&f->ematches);kfree (f);
@@ -106,6 +104,7 @@ static void basic_destroy(struct tcf_proto *tp)list_for_each_entry_safe (f, n, &head->flist, link) {list_del_rcu (&f->link); +tcf_unbind_filter (tp, &f->res);call_rcu (&f->rcu, basic_delete_filter); }RCU_INIT_POINTER (tp->root,NULL );
@@ -120,6 +119,7 @@ static int basic_delete(struct tcf_proto *tp, unsigned long arg)list_for_each_entry (t, &head->flist, link)if (t == f) {list_del_rcu (&t->link); +tcf_unbind_filter (tp, &t->res);call_rcu (&t->rcu, basic_delete_filter);return 0 ; }
@@ -222,6 +222,7 @@ static int basic_change(struct net *net, struct sk_buff *in_skb,if (fold) {list_replace_rcu (&fold->link, &fnew->link); +tcf_unbind_filter (tp, &fold->res);call_rcu (&fold->rcu, basic_delete_filter); }else {list_add_rcu (&fnew->link, &head->flist);
net/sched/cls_bpf.c +3 -1
@@ -92,7 +92,6 @@ static int cls_bpf_init(struct tcf_proto *tp)static void cls_bpf_delete_prog (struct tcf_proto *tp,struct cls_bpf_prog *prog) { -tcf_unbind_filter (tp, &prog->res);tcf_exts_destroy (&prog->exts);bpf_prog_destroy (prog->filter);
@@ -116,6 +115,7 @@ static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)list_for_each_entry (prog, &head->plist, link) {if (prog == todel) {list_del_rcu (&prog->link); +tcf_unbind_filter (tp, &prog->res);call_rcu (&prog->rcu, __cls_bpf_delete_prog);return 0 ; }
@@ -131,6 +131,7 @@ static void cls_bpf_destroy(struct tcf_proto *tp)list_for_each_entry_safe (prog, tmp, &head->plist, link) {list_del_rcu (&prog->link); +tcf_unbind_filter (tp, &prog->res);call_rcu (&prog->rcu, __cls_bpf_delete_prog); }
@@ -282,6 +283,7 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,if (oldprog) {list_replace_rcu (&prog->link, &oldprog->link); +tcf_unbind_filter (tp, &oldprog->res);call_rcu (&oldprog->rcu, __cls_bpf_delete_prog); }else {list_add_rcu (&prog->link, &head->plist);
net/sched/cls_fw.c +3 -2
@@ -123,9 +123,7 @@ static int fw_init(struct tcf_proto *tp)static void fw_delete_filter (struct rcu_head *head) { struct fw_filter *f = container_of(head, struct fw_filter, rcu); -struct tcf_proto *tp = f->tp; -tcf_unbind_filter (tp, &f->res);tcf_exts_destroy (&f->exts);kfree (f); }
@@ -143,6 +141,7 @@ static void fw_destroy(struct tcf_proto *tp)while ((f =rtnl_dereference (head->ht[h])) !=NULL ) {RCU_INIT_POINTER (head->ht[h],rtnl_dereference (f->next)); +tcf_unbind_filter (tp, &f->res);call_rcu (&f->rcu, fw_delete_filter); } }
@@ -166,6 +165,7 @@ static int fw_delete(struct tcf_proto *tp, unsigned long arg) fp = &pfp->next, pfp = rtnl_dereference(*fp)) {if (pfp == f) {RCU_INIT_POINTER (*fp,rtnl_dereference (f->next)); +tcf_unbind_filter (tp, &f->res);call_rcu (&f->rcu, fw_delete_filter);return 0 ; }
@@ -280,6 +280,7 @@ static int fw_change(struct net *net, struct sk_buff *in_skb,RCU_INIT_POINTER (fnew->next,rtnl_dereference (pfp->next));rcu_assign_pointer (*fp, fnew); +tcf_unbind_filter (tp, &f->res);call_rcu (&f->rcu, fw_delete_filter); *arg = (unsigned long )fnew;
net/sched/cls_route.c +5 -3
@@ -269,9 +269,7 @@ static void route4_delete_filter(struct rcu_head *head) { struct route4_filter *f = container_of(head, struct route4_filter, rcu); -struct tcf_proto *tp = f->tp; -tcf_unbind_filter (tp, &f->res);tcf_exts_destroy (&f->exts);kfree (f); }
@@ -297,6 +295,7 @@ static void route4_destroy(struct tcf_proto *tp) next =rtnl_dereference (f->next);RCU_INIT_POINTER (b->ht[h2], next); +tcf_unbind_filter (tp, &f->res);call_rcu (&f->rcu, route4_delete_filter); } }
@@ -338,6 +337,7 @@ static int route4_delete(struct tcf_proto *tp, unsigned long arg)route4_reset_fastmap (head);/* Delete it */ +tcf_unbind_filter (tp, &f->res);call_rcu (&f->rcu, route4_delete_filter);/* Strip RTNL protected tree */
@@ -545,8 +545,10 @@ static int route4_change(struct net *net, struct sk_buff *in_skb,route4_reset_fastmap (head); *arg = (unsigned long )f; -if (fold) +if (fold) { +tcf_unbind_filter (tp, &fold->res);call_rcu (&fold->rcu, route4_delete_filter); + }return 0 ; errout:
Re: [net-next PATCH v1 3/3] net: sched: do not use tcf_proto 'tp' argument from call_rcu
Quoted 9 lines · John Fastabend
Using the
tcf_protopointer 'tp' from inside the classifiers callback is not valid because it may have been cleaned up by anothercall_rcuoccuring on another CPU.'tp' is currently being used by
tcf_unbind_filter()in this patch we move instances oftcf_unbind_filteroutside of thecall_rcu()context. This is safe to do because any running schedulers will either read the valid class field or it will be zeroed.
Quoted 8 lines
And all schedulers today when the class is 0 do a lookup using the same call used by the
tcf_exts_bind(). So even if we have a running classifier hit the null class pointer it will do a lookup and get to the same result. This is particularly fragile at the moment because the only way to verify this is to audit the schedulers call sites.Reported-by Cong Wang <[email protected]>Signed-off-by John Fastabend <[email protected]>
David Miller
maintainerFrom: John Fastabend <[email protected]>
Date: Sun, 05 Oct 2014 21:27:25 -0700
Quoted 12 lines
This fixes the use of
tcf_protofrom RCU callbacks it requires moving the unbind calls out of the callbacks and removing thetcf_protoargument from thetcf_em_tree_destroy().This is a rework of two previous series and addresses comments from Cong. And should apply against latest net-next.
The previous series links below for reference:
(1/2) net: sched: do not use
tcf_proto'tp' argument fromcall_rcu
http://patchwork.ozlabs.org/patch/396149/
Quoted 6 lines
(2/2) net: sched: replace ematch calls to use struct net
http://patchwork.ozlabs.org/patch/396150/net: sched:
cls_cgrouptear down exts and ematch from rcu callback
http://patchwork.ozlabs.org/patch/396307/
Series applied, thanks.