Doug / smarc-fsl-linux-kernel

Download as
Browse Code ยป

Commit c7de2cf053420d63bac85133469c965d4b1083e1

Authored by Eric Dumazet
Committed by David S. Miller
1 parent cbd6890c59
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

pkt_sched: gen_kill_estimator() rcu fixes 

gen_kill_estimator() API is incomplete or not well documented, since
caller should make sure an RCU grace period is respected before
freeing stats_lock.

This was partially addressed in commit 5d944c640b4
(gen_estimator: deadlock fix), but same problem exist for all
gen_kill_estimator() users, if lock they use is not already RCU
protected.

A code review shows xt_RATEEST.c, act_api.c, act_police.c have this
problem. Other are ok because they use qdisc lock, already RCU
protected.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Showing 6 changed files with 36 additions and 3 deletions Side-by-side Diff

include/net/act_api.h
Diff comments   View file @ c7de2cf
... ... @@ -20,6 +20,7 @@
20 20 struct gnet_stats_queue tcfc_qstats;
21 21 struct gnet_stats_rate_est tcfc_rate_est;
22 22 spinlock_t tcfc_lock;
  23 + struct rcu_head tcfc_rcu;
23 24 };
24 25 #define tcf_next common.tcfc_next
25 26 #define tcf_index common.tcfc_index
... ... @@ -32,6 +33,7 @@
32 33 #define tcf_qstats common.tcfc_qstats
33 34 #define tcf_rate_est common.tcfc_rate_est
34 35 #define tcf_lock common.tcfc_lock
  36 +#define tcf_rcu common.tcfc_rcu
35 37  
36 38 struct tcf_police {
37 39 struct tcf_common common;
include/net/netfilter/xt_rateest.h
Diff comments   View file @ c7de2cf
... ... @@ -9,6 +9,7 @@
9 9 struct gnet_estimator params;
10 10 struct gnet_stats_rate_est rstats;
11 11 struct gnet_stats_basic_packed bstats;
  12 + struct rcu_head rcu;
12 13 };
13 14  
14 15 extern struct xt_rateest *xt_rateest_lookup(const char *name);
net/core/gen_estimator.c
Diff comments   View file @ c7de2cf
... ... @@ -263,6 +263,7 @@
263 263 *
264 264 * Removes the rate estimator specified by &bstats and &rate_est.
265 265 *
  266 + * Note : Caller should respect an RCU grace period before freeing stats_lock
266 267 */
267 268 void gen_kill_estimator(struct gnet_stats_basic_packed *bstats,
268 269 struct gnet_stats_rate_est *rate_est)
net/netfilter/xt_RATEEST.c
Diff comments   View file @ c7de2cf
... ... @@ -60,13 +60,22 @@
60 60 }
61 61 EXPORT_SYMBOL_GPL(xt_rateest_lookup);
62 62  
  63 +static void xt_rateest_free_rcu(struct rcu_head *head)
  64 +{
  65 + kfree(container_of(head, struct xt_rateest, rcu));
  66 +}
  67 +
63 68 void xt_rateest_put(struct xt_rateest *est)
64 69 {
65 70 mutex_lock(&xt_rateest_mutex);
66 71 if (--est->refcnt == 0) {
67 72 hlist_del(&est->list);
68 73 gen_kill_estimator(&est->bstats, &est->rstats);
69   - kfree(est);
  74 + /*
  75 + * gen_estimator est_timer() might access est->lock or bstats,
  76 + * wait a RCU grace period before freeing 'est'
  77 + */
  78 + call_rcu(&est->rcu, xt_rateest_free_rcu);
70 79 }
71 80 mutex_unlock(&xt_rateest_mutex);
72 81 }
... ... @@ -179,6 +188,7 @@
179 188 static void __exit xt_rateest_tg_fini(void)
180 189 {
181 190 xt_unregister_target(&xt_rateest_tg_reg);
  191 + rcu_barrier(); /* Wait for completion of call_rcu()'s (xt_rateest_free_rcu) */
182 192 }
183 193  
184 194  
... ... @@ -26,6 +26,11 @@
26 26 #include <net/act_api.h>
27 27 #include <net/netlink.h>
28 28  
  29 +static void tcf_common_free_rcu(struct rcu_head *head)
  30 +{
  31 + kfree(container_of(head, struct tcf_common, tcfc_rcu));
  32 +}
  33 +
29 34 void tcf_hash_destroy(struct tcf_common *p, struct tcf_hashinfo *hinfo)
30 35 {
31 36 unsigned int h = tcf_hash(p->tcfc_index, hinfo->hmask);
... ... @@ -38,7 +43,11 @@
38 43 write_unlock_bh(hinfo->lock);
39 44 gen_kill_estimator(&p->tcfc_bstats,
40 45 &p->tcfc_rate_est);
41   - kfree(p);
  46 + /*
  47 + * gen_estimator est_timer() might access p->tcfc_lock
  48 + * or bstats, wait a RCU grace period before freeing p
  49 + */
  50 + call_rcu(&p->tcfc_rcu, tcf_common_free_rcu);
42 51 return;
43 52 }
44 53 }
net/sched/act_police.c
Diff comments   View file @ c7de2cf
... ... @@ -97,6 +97,11 @@
97 97 goto done;
98 98 }
99 99  
  100 +static void tcf_police_free_rcu(struct rcu_head *head)
  101 +{
  102 + kfree(container_of(head, struct tcf_police, tcf_rcu));
  103 +}
  104 +
100 105 static void tcf_police_destroy(struct tcf_police *p)
101 106 {
102 107 unsigned int h = tcf_hash(p->tcf_index, POL_TAB_MASK);
... ... @@ -113,7 +118,11 @@
113 118 qdisc_put_rtab(p->tcfp_R_tab);
114 119 if (p->tcfp_P_tab)
115 120 qdisc_put_rtab(p->tcfp_P_tab);
116   - kfree(p);
  121 + /*
  122 + * gen_estimator est_timer() might access p->tcf_lock
  123 + * or bstats, wait a RCU grace period before freeing p
  124 + */
  125 + call_rcu(&p->tcf_rcu, tcf_police_free_rcu);
117 126 return;
118 127 }
119 128 }
... ... @@ -397,6 +406,7 @@
397 406 police_cleanup_module(void)
398 407 {
399 408 tcf_unregister_action(&act_police_ops);
  409 + rcu_barrier(); /* Wait for completion of call_rcu()'s (tcf_police_free_rcu) */
400 410 }
401 411  
402 412 module_init(police_init_module);