Re: [PATCH 01/14] net: sched: use rcu for action cookie update

kbuild test robot
2018-05-14T23:40:19Z

Hi Vlad,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net/master]
[also build test WARNING on v4.17-rc5 next-20180514]
[cannot apply to net-next/master]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Vlad-Buslov/Modify-action-API-for-implementing-lockless-actions/20180515-025420
reproduce:
# apt-get install sparse
make ARCH=x86_64 allmodconfig
make C=1 CF=-D__CHECK_ENDIAN__

sparse warnings: (new ones prefixed by >>)

>> net/sched/act_api.c:71:15: sparse: incorrect type in initializer (different address spaces) @@ expected struct tc_cookie [noderef] <asn:4>*__ret @@ got [noderef] <asn:4>*__ret @@
net/sched/act_api.c:71:15: expected struct tc_cookie [noderef] <asn:4>*__ret
net/sched/act_api.c:71:15: got struct tc_cookie *new_cookie
>> net/sched/act_api.c:71:13: sparse: incorrect type in assignment (different address spaces) @@ expected struct tc_cookie *old @@ got struct tc_cookie [noderef] <struct tc_cookie *old @@
net/sched/act_api.c:71:13: expected struct tc_cookie *old
net/sched/act_api.c:71:13: got struct tc_cookie [noderef] <asn:4>*[assigned] __ret
>> net/sched/act_api.c:132:48: sparse: dereference of noderef expression

vim +71 net/sched/act_api.c

65
66 static void tcf_set_action_cookie(struct tc_cookie __rcu **old_cookie,
67 struct tc_cookie *new_cookie)
68 {
69 struct tc_cookie *old;
70
> 71 old = xchg(old_cookie, new_cookie);
72 if (old)
73 call_rcu(&old->rcu, tcf_free_cookie_rcu);
74 }
75
76 /* XXX: For standalone actions, we don't need a RCU grace period either, because
77 * actions are always connected to filters and filters are already destroyed in
78 * RCU callbacks, so after a RCU grace period actions are already disconnected
79 * from filters. Readers later can not find us.
80 */
81 static void free_tcf(struct tc_action *p)
82 {
83 free_percpu(p->cpu_bstats);
84 free_percpu(p->cpu_qstats);
85
86 tcf_set_action_cookie(&p->act_cookie, NULL);
87 if (p->goto_chain)
88 tcf_action_goto_chain_fini(p);
89
90 kfree(p);
91 }
92
93 static void tcf_idr_remove(struct tcf_idrinfo *idrinfo, struct tc_action *p)
94 {
95 spin_lock_bh(&idrinfo->lock);
96 idr_remove(&idrinfo->action_idr, p->tcfa_index);
97 spin_unlock_bh(&idrinfo->lock);
98 gen_kill_estimator(&p->tcfa_rate_est);
99 free_tcf(p);
100 }
101
102 int __tcf_idr_release(struct tc_action *p, bool bind, bool strict)
103 {
104 int ret = 0;
105
106 ASSERT_RTNL();
107
108 if (p) {
109 if (bind)
110 p->tcfa_bindcnt--;
111 else if (strict && p->tcfa_bindcnt > 0)
112 return -EPERM;
113
114 p->tcfa_refcnt--;
115 if (p->tcfa_bindcnt <= 0 && p->tcfa_refcnt <= 0) {
116 if (p->ops->cleanup)
117 p->ops->cleanup(p);
118 tcf_idr_remove(p->idrinfo, p);
119 ret = ACT_P_DELETED;
120 }
121 }
122
123 return ret;
124 }
125 EXPORT_SYMBOL(__tcf_idr_release);
126
127 static size_t tcf_action_shared_attrs_size(const struct tc_action *act)
128 {
129 u32 cookie_len = 0;
130
131 if (act->act_cookie)
> 132 cookie_len = nla_total_size(act->act_cookie->len);
133
134 return nla_total_size(0) /* action number nested */
135 + nla_total_size(IFNAMSIZ) /* TCA_ACT_KIND */
136 + cookie_len /* TCA_ACT_COOKIE */
137 + nla_total_size(0) /* TCA_ACT_STATS nested */
138 /* TCA_STATS_BASIC */
139 + nla_total_size_64bit(sizeof(struct gnet_stats_basic))
140 /* TCA_STATS_QUEUE */
141 + nla_total_size_64bit(sizeof(struct gnet_stats_queue))
142 + nla_total_size(0) /* TCA_OPTIONS nested */
143 + nla_total_size(sizeof(struct tcf_t)); /* TCA_GACT_TM */
144 }
145

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