From 1f947bf151e90ec0baad294881607ebf321a2863 Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Fri, 12 Sep 2014 20:10:24 -0700 Subject: [PATCH] net: sched: rcu'ify cls_bpf This patch makes the cls_bpf classifier RCU safe. The tcf_lock was being used to protect a list of cls_bpf_prog now this list is RCU safe and updates occur with rcu_replace. Signed-off-by: John Fastabend Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/sched/cls_bpf.c | 94 ++++++++++++++++++++++----------------------- 1 file changed, 47 insertions(+), 47 deletions(-) diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c index 0e30d58149da..6a7386e6e5a8 100644 --- a/net/sched/cls_bpf.c +++ b/net/sched/cls_bpf.c @@ -27,6 +27,7 @@ MODULE_DESCRIPTION("TC BPF based classifier"); struct cls_bpf_head { struct list_head plist; u32 hgen; + struct rcu_head rcu; }; struct cls_bpf_prog { @@ -37,6 +38,8 @@ struct cls_bpf_prog { struct list_head link; u32 handle; u16 bpf_len; + struct tcf_proto *tp; + struct rcu_head rcu; }; static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = { @@ -49,11 +52,11 @@ static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = { static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp, struct tcf_result *res) { - struct cls_bpf_head *head = tp->root; + struct cls_bpf_head *head = rcu_dereference(tp->root); struct cls_bpf_prog *prog; int ret; - list_for_each_entry(prog, &head->plist, link) { + list_for_each_entry_rcu(prog, &head->plist, link) { int filter_res = BPF_PROG_RUN(prog->filter, skb); if (filter_res == 0) @@ -81,8 +84,8 @@ static int cls_bpf_init(struct tcf_proto *tp) if (head == NULL) return -ENOBUFS; - INIT_LIST_HEAD(&head->plist); - tp->root = head; + INIT_LIST_HEAD_RCU(&head->plist); + rcu_assign_pointer(tp->root, head); return 0; } @@ -98,18 +101,22 @@ static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog) kfree(prog); } +static void __cls_bpf_delete_prog(struct rcu_head *rcu) +{ + struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu); + + cls_bpf_delete_prog(prog->tp, prog); +} + static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg) { - struct cls_bpf_head *head = tp->root; + struct cls_bpf_head *head = rtnl_dereference(tp->root); struct cls_bpf_prog *prog, *todel = (struct cls_bpf_prog *) arg; list_for_each_entry(prog, &head->plist, link) { if (prog == todel) { - tcf_tree_lock(tp); - list_del(&prog->link); - tcf_tree_unlock(tp); - - cls_bpf_delete_prog(tp, prog); + list_del_rcu(&prog->link); + call_rcu(&prog->rcu, __cls_bpf_delete_prog); return 0; } } @@ -119,27 +126,28 @@ static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg) static void cls_bpf_destroy(struct tcf_proto *tp) { - struct cls_bpf_head *head = tp->root; + struct cls_bpf_head *head = rtnl_dereference(tp->root); struct cls_bpf_prog *prog, *tmp; list_for_each_entry_safe(prog, tmp, &head->plist, link) { - list_del(&prog->link); - cls_bpf_delete_prog(tp, prog); + list_del_rcu(&prog->link); + call_rcu(&prog->rcu, __cls_bpf_delete_prog); } - kfree(head); + RCU_INIT_POINTER(tp->root, NULL); + kfree_rcu(head, rcu); } static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle) { - struct cls_bpf_head *head = tp->root; + struct cls_bpf_head *head = rtnl_dereference(tp->root); struct cls_bpf_prog *prog; unsigned long ret = 0UL; if (head == NULL) return 0UL; - list_for_each_entry(prog, &head->plist, link) { + list_for_each_entry_rcu(prog, &head->plist, link) { if (prog->handle == handle) { ret = (unsigned long) prog; break; @@ -158,10 +166,10 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp, unsigned long base, struct nlattr **tb, struct nlattr *est, bool ovr) { - struct sock_filter *bpf_ops, *bpf_old; + struct sock_filter *bpf_ops; struct tcf_exts exts; struct sock_fprog_kern tmp; - struct bpf_prog *fp, *fp_old; + struct bpf_prog *fp; u16 bpf_size, bpf_len; u32 classid; int ret; @@ -197,26 +205,15 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp, if (ret) goto errout_free; - tcf_tree_lock(tp); - fp_old = prog->filter; - bpf_old = prog->bpf_ops; - prog->bpf_len = bpf_len; prog->bpf_ops = bpf_ops; prog->filter = fp; prog->res.classid = classid; - tcf_tree_unlock(tp); tcf_bind_filter(tp, &prog->res, base); tcf_exts_change(tp, &prog->exts, &exts); - if (fp_old) - bpf_prog_destroy(fp_old); - if (bpf_old) - kfree(bpf_old); - return 0; - errout_free: kfree(bpf_ops); errout: @@ -244,9 +241,10 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, u32 handle, struct nlattr **tca, unsigned long *arg, bool ovr) { - struct cls_bpf_head *head = tp->root; - struct cls_bpf_prog *prog = (struct cls_bpf_prog *) *arg; + struct cls_bpf_head *head = rtnl_dereference(tp->root); + struct cls_bpf_prog *oldprog = (struct cls_bpf_prog *) *arg; struct nlattr *tb[TCA_BPF_MAX + 1]; + struct cls_bpf_prog *prog; int ret; if (tca[TCA_OPTIONS] == NULL) @@ -256,18 +254,19 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, if (ret < 0) return ret; - if (prog != NULL) { - if (handle && prog->handle != handle) - return -EINVAL; - return cls_bpf_modify_existing(net, tp, prog, base, tb, - tca[TCA_RATE], ovr); - } - prog = kzalloc(sizeof(*prog), GFP_KERNEL); - if (prog == NULL) + if (!prog) return -ENOBUFS; tcf_exts_init(&prog->exts, TCA_BPF_ACT, TCA_BPF_POLICE); + + if (oldprog) { + if (handle && oldprog->handle != handle) { + ret = -EINVAL; + goto errout; + } + } + if (handle == 0) prog->handle = cls_bpf_grab_new_handle(tp, head); else @@ -281,16 +280,17 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, if (ret < 0) goto errout; - tcf_tree_lock(tp); - list_add(&prog->link, &head->plist); - tcf_tree_unlock(tp); + if (oldprog) { + list_replace_rcu(&prog->link, &oldprog->link); + call_rcu(&oldprog->rcu, __cls_bpf_delete_prog); + } else { + list_add_rcu(&prog->link, &head->plist); + } *arg = (unsigned long) prog; - return 0; errout: - if (*arg == 0UL && prog) - kfree(prog); + kfree(prog); return ret; } @@ -339,10 +339,10 @@ static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh, static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg) { - struct cls_bpf_head *head = tp->root; + struct cls_bpf_head *head = rtnl_dereference(tp->root); struct cls_bpf_prog *prog; - list_for_each_entry(prog, &head->plist, link) { + list_for_each_entry_rcu(prog, &head->plist, link) { if (arg->count < arg->skip) goto skip; if (arg->fn(tp, (unsigned long) prog, arg) < 0) {