From: Eric Dumazet Date: Wed, 9 Jun 2010 02:09:23 +0000 (+0000) Subject: pkt_sched: gen_kill_estimator() rcu fixes X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=c7de2cf053420d63bac85133469c965d4b1083e1;p=linux-beck.git 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 Signed-off-by: David S. Miller --- diff --git a/include/net/act_api.h b/include/net/act_api.h index c05fd717c588..bab385f13ac3 100644 --- a/include/net/act_api.h +++ b/include/net/act_api.h @@ -20,6 +20,7 @@ struct tcf_common { struct gnet_stats_queue tcfc_qstats; struct gnet_stats_rate_est tcfc_rate_est; spinlock_t tcfc_lock; + struct rcu_head tcfc_rcu; }; #define tcf_next common.tcfc_next #define tcf_index common.tcfc_index @@ -32,6 +33,7 @@ struct tcf_common { #define tcf_qstats common.tcfc_qstats #define tcf_rate_est common.tcfc_rate_est #define tcf_lock common.tcfc_lock +#define tcf_rcu common.tcfc_rcu struct tcf_police { struct tcf_common common; diff --git a/include/net/netfilter/xt_rateest.h b/include/net/netfilter/xt_rateest.h index ddbf37e19616..5e1427795928 100644 --- a/include/net/netfilter/xt_rateest.h +++ b/include/net/netfilter/xt_rateest.h @@ -9,6 +9,7 @@ struct xt_rateest { struct gnet_estimator params; struct gnet_stats_rate_est rstats; struct gnet_stats_basic_packed bstats; + struct rcu_head rcu; }; extern struct xt_rateest *xt_rateest_lookup(const char *name); diff --git a/net/core/gen_estimator.c b/net/core/gen_estimator.c index 785e5276a300..9fbe7f7429b0 100644 --- a/net/core/gen_estimator.c +++ b/net/core/gen_estimator.c @@ -263,6 +263,7 @@ static void __gen_kill_estimator(struct rcu_head *head) * * Removes the rate estimator specified by &bstats and &rate_est. * + * Note : Caller should respect an RCU grace period before freeing stats_lock */ void gen_kill_estimator(struct gnet_stats_basic_packed *bstats, struct gnet_stats_rate_est *rate_est) diff --git a/net/netfilter/xt_RATEEST.c b/net/netfilter/xt_RATEEST.c index 69c01e10f8af..de079abd5bc8 100644 --- a/net/netfilter/xt_RATEEST.c +++ b/net/netfilter/xt_RATEEST.c @@ -60,13 +60,22 @@ struct xt_rateest *xt_rateest_lookup(const char *name) } EXPORT_SYMBOL_GPL(xt_rateest_lookup); +static void xt_rateest_free_rcu(struct rcu_head *head) +{ + kfree(container_of(head, struct xt_rateest, rcu)); +} + void xt_rateest_put(struct xt_rateest *est) { mutex_lock(&xt_rateest_mutex); if (--est->refcnt == 0) { hlist_del(&est->list); gen_kill_estimator(&est->bstats, &est->rstats); - kfree(est); + /* + * gen_estimator est_timer() might access est->lock or bstats, + * wait a RCU grace period before freeing 'est' + */ + call_rcu(&est->rcu, xt_rateest_free_rcu); } mutex_unlock(&xt_rateest_mutex); } @@ -179,6 +188,7 @@ static int __init xt_rateest_tg_init(void) static void __exit xt_rateest_tg_fini(void) { xt_unregister_target(&xt_rateest_tg_reg); + rcu_barrier(); /* Wait for completion of call_rcu()'s (xt_rateest_free_rcu) */ } diff --git a/net/sched/act_api.c b/net/sched/act_api.c index 972378f47f3c..23b25f89e7e0 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -26,6 +26,11 @@ #include #include +static void tcf_common_free_rcu(struct rcu_head *head) +{ + kfree(container_of(head, struct tcf_common, tcfc_rcu)); +} + void tcf_hash_destroy(struct tcf_common *p, struct tcf_hashinfo *hinfo) { unsigned int h = tcf_hash(p->tcfc_index, hinfo->hmask); @@ -38,7 +43,11 @@ void tcf_hash_destroy(struct tcf_common *p, struct tcf_hashinfo *hinfo) write_unlock_bh(hinfo->lock); gen_kill_estimator(&p->tcfc_bstats, &p->tcfc_rate_est); - kfree(p); + /* + * gen_estimator est_timer() might access p->tcfc_lock + * or bstats, wait a RCU grace period before freeing p + */ + call_rcu(&p->tcfc_rcu, tcf_common_free_rcu); return; } } diff --git a/net/sched/act_police.c b/net/sched/act_police.c index 654f73dff7c1..537a48732e9e 100644 --- a/net/sched/act_police.c +++ b/net/sched/act_police.c @@ -97,6 +97,11 @@ nla_put_failure: goto done; } +static void tcf_police_free_rcu(struct rcu_head *head) +{ + kfree(container_of(head, struct tcf_police, tcf_rcu)); +} + static void tcf_police_destroy(struct tcf_police *p) { unsigned int h = tcf_hash(p->tcf_index, POL_TAB_MASK); @@ -113,7 +118,11 @@ static void tcf_police_destroy(struct tcf_police *p) qdisc_put_rtab(p->tcfp_R_tab); if (p->tcfp_P_tab) qdisc_put_rtab(p->tcfp_P_tab); - kfree(p); + /* + * gen_estimator est_timer() might access p->tcf_lock + * or bstats, wait a RCU grace period before freeing p + */ + call_rcu(&p->tcf_rcu, tcf_police_free_rcu); return; } } @@ -397,6 +406,7 @@ static void __exit police_cleanup_module(void) { tcf_unregister_action(&act_police_ops); + rcu_barrier(); /* Wait for completion of call_rcu()'s (tcf_police_free_rcu) */ } module_init(police_init_module);