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 5d944c640b
(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>
This commit is contained in:
Eric Dumazet 2010-06-09 02:09:23 +00:00 committed by David S. Miller
parent cbd6890c59
commit c7de2cf053
6 changed files with 36 additions and 3 deletions

View File

@ -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;

View File

@ -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);

View File

@ -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)

View File

@ -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) */
}

View File

@ -26,6 +26,11 @@
#include <net/act_api.h>
#include <net/netlink.h>
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;
}
}

View File

@ -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);