From 8ab19ea36c5c5340ff598e4d15fc084eb65671dc Mon Sep 17 00:00:00 2001 From: Sven Wegener Date: Sun, 10 Aug 2008 09:17:59 +0000 Subject: ipvs: Fix possible deadlock in estimator code There is a slight chance for a deadlock in the estimator code. We can't call del_timer_sync() while holding our lock, as the timer might be active and spinning for the lock on another cpu. Work around this issue by using try_to_del_timer_sync() and releasing the lock. We could actually delete the timer outside of our lock, as the add and kill functions are only every called from userspace via [gs]etsockopt() and are serialized by a mutex, but better make this explicit. Signed-off-by: Sven Wegener Cc: stable Acked-by: Simon Horman --- net/ipv4/ipvs/ip_vs_est.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'net/ipv4/ipvs/ip_vs_est.c') diff --git a/net/ipv4/ipvs/ip_vs_est.c b/net/ipv4/ipvs/ip_vs_est.c index bc04eedd6dbb..1d6e58e502fd 100644 --- a/net/ipv4/ipvs/ip_vs_est.c +++ b/net/ipv4/ipvs/ip_vs_est.c @@ -170,8 +170,11 @@ void ip_vs_kill_estimator(struct ip_vs_stats *stats) kfree(est); killed++; } - if (killed && est_list == NULL) - del_timer_sync(&est_timer); + while (killed && !est_list && try_to_del_timer_sync(&est_timer) < 0) { + write_unlock_bh(&est_lock); + cpu_relax(); + write_lock_bh(&est_lock); + } write_unlock_bh(&est_lock); } -- cgit v1.2.3 From 3a14a313f9b406c37ab7e3f855b060eb8587b8c7 Mon Sep 17 00:00:00 2001 From: Sven Wegener Date: Sun, 10 Aug 2008 18:24:41 +0000 Subject: ipvs: Embed estimator object into stats object There's no reason for dynamically allocating an estimator object for every stats object. Directly embed an estimator object into every stats object and switch to using the kernel-provided list implementation. This makes the code much simpler and faster, as we do not need to traverse the list of all estimators to find the one belonging to a stats object. There's no need to use an rwlock, as we only have one reader. Also reorder the members of the estimator structure slightly to avoid padding overhead. This can't be done with the stats object as the members are currently copied to our user space object via memcpy() and changing it would break ABI. Signed-off-by: Sven Wegener Acked-by: Simon Horman --- include/net/ip_vs.h | 28 ++++++++++- net/ipv4/ipvs/ip_vs_ctl.c | 2 +- net/ipv4/ipvs/ip_vs_est.c | 117 +++++++++++++++------------------------------- 3 files changed, 65 insertions(+), 82 deletions(-) (limited to 'net/ipv4/ipvs/ip_vs_est.c') diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h index c8ee9b89b023..7312c3dd309f 100644 --- a/include/net/ip_vs.h +++ b/include/net/ip_vs.h @@ -140,8 +140,24 @@ struct ip_vs_seq { /* - * IPVS statistics object + * IPVS statistics objects */ +struct ip_vs_estimator { + struct list_head list; + + u64 last_inbytes; + u64 last_outbytes; + u32 last_conns; + u32 last_inpkts; + u32 last_outpkts; + + u32 cps; + u32 inpps; + u32 outpps; + u32 inbps; + u32 outbps; +}; + struct ip_vs_stats { __u32 conns; /* connections scheduled */ @@ -156,7 +172,15 @@ struct ip_vs_stats __u32 inbps; /* current in byte rate */ __u32 outbps; /* current out byte rate */ + /* + * Don't add anything before the lock, because we use memcpy() to copy + * the members before the lock to struct ip_vs_stats_user in + * ip_vs_ctl.c. + */ + spinlock_t lock; /* spin lock */ + + struct ip_vs_estimator est; /* estimator */ }; struct dst_entry; @@ -659,7 +683,7 @@ extern void ip_vs_sync_conn(struct ip_vs_conn *cp); /* * IPVS rate estimator prototypes (from ip_vs_est.c) */ -extern int ip_vs_new_estimator(struct ip_vs_stats *stats); +extern void ip_vs_new_estimator(struct ip_vs_stats *stats); extern void ip_vs_kill_estimator(struct ip_vs_stats *stats); extern void ip_vs_zero_estimator(struct ip_vs_stats *stats); diff --git a/net/ipv4/ipvs/ip_vs_ctl.c b/net/ipv4/ipvs/ip_vs_ctl.c index 999d884e8862..d651bce05493 100644 --- a/net/ipv4/ipvs/ip_vs_ctl.c +++ b/net/ipv4/ipvs/ip_vs_ctl.c @@ -684,8 +684,8 @@ ip_vs_zero_stats(struct ip_vs_stats *stats) { spin_lock_bh(&stats->lock); memset(stats, 0, (char *)&stats->lock - (char *)stats); - spin_unlock_bh(&stats->lock); ip_vs_zero_estimator(stats); + spin_unlock_bh(&stats->lock); } /* diff --git a/net/ipv4/ipvs/ip_vs_est.c b/net/ipv4/ipvs/ip_vs_est.c index 1d6e58e502fd..5a20f93bd7f9 100644 --- a/net/ipv4/ipvs/ip_vs_est.c +++ b/net/ipv4/ipvs/ip_vs_est.c @@ -17,6 +17,7 @@ #include #include #include +#include #include @@ -44,28 +45,11 @@ */ -struct ip_vs_estimator -{ - struct ip_vs_estimator *next; - struct ip_vs_stats *stats; - - u32 last_conns; - u32 last_inpkts; - u32 last_outpkts; - u64 last_inbytes; - u64 last_outbytes; - - u32 cps; - u32 inpps; - u32 outpps; - u32 inbps; - u32 outbps; -}; +static void estimation_timer(unsigned long arg); - -static struct ip_vs_estimator *est_list = NULL; -static DEFINE_RWLOCK(est_lock); -static struct timer_list est_timer; +static LIST_HEAD(est_list); +static DEFINE_SPINLOCK(est_lock); +static DEFINE_TIMER(est_timer, estimation_timer, 0, 0); static void estimation_timer(unsigned long arg) { @@ -76,9 +60,9 @@ static void estimation_timer(unsigned long arg) u64 n_inbytes, n_outbytes; u32 rate; - read_lock(&est_lock); - for (e = est_list; e; e = e->next) { - s = e->stats; + spin_lock(&est_lock); + list_for_each_entry(e, &est_list, list) { + s = container_of(e, struct ip_vs_stats, est); spin_lock(&s->lock); n_conns = s->conns; @@ -114,19 +98,16 @@ static void estimation_timer(unsigned long arg) s->outbps = (e->outbps+0xF)>>5; spin_unlock(&s->lock); } - read_unlock(&est_lock); + spin_unlock(&est_lock); mod_timer(&est_timer, jiffies + 2*HZ); } -int ip_vs_new_estimator(struct ip_vs_stats *stats) +void ip_vs_new_estimator(struct ip_vs_stats *stats) { - struct ip_vs_estimator *est; + struct ip_vs_estimator *est = &stats->est; - est = kzalloc(sizeof(*est), GFP_KERNEL); - if (est == NULL) - return -ENOMEM; + INIT_LIST_HEAD(&est->list); - est->stats = stats; est->last_conns = stats->conns; est->cps = stats->cps<<10; @@ -142,62 +123,40 @@ int ip_vs_new_estimator(struct ip_vs_stats *stats) est->last_outbytes = stats->outbytes; est->outbps = stats->outbps<<5; - write_lock_bh(&est_lock); - est->next = est_list; - if (est->next == NULL) { - setup_timer(&est_timer, estimation_timer, 0); - est_timer.expires = jiffies + 2*HZ; - add_timer(&est_timer); - } - est_list = est; - write_unlock_bh(&est_lock); - return 0; + spin_lock_bh(&est_lock); + if (list_empty(&est_list)) + mod_timer(&est_timer, jiffies + 2 * HZ); + list_add(&est->list, &est_list); + spin_unlock_bh(&est_lock); } void ip_vs_kill_estimator(struct ip_vs_stats *stats) { - struct ip_vs_estimator *est, **pest; - int killed = 0; - - write_lock_bh(&est_lock); - pest = &est_list; - while ((est=*pest) != NULL) { - if (est->stats != stats) { - pest = &est->next; - continue; - } - *pest = est->next; - kfree(est); - killed++; - } - while (killed && !est_list && try_to_del_timer_sync(&est_timer) < 0) { - write_unlock_bh(&est_lock); + struct ip_vs_estimator *est = &stats->est; + + spin_lock_bh(&est_lock); + list_del(&est->list); + while (list_empty(&est_list) && try_to_del_timer_sync(&est_timer) < 0) { + spin_unlock_bh(&est_lock); cpu_relax(); - write_lock_bh(&est_lock); + spin_lock_bh(&est_lock); } - write_unlock_bh(&est_lock); + spin_unlock_bh(&est_lock); } void ip_vs_zero_estimator(struct ip_vs_stats *stats) { - struct ip_vs_estimator *e; - - write_lock_bh(&est_lock); - for (e = est_list; e; e = e->next) { - if (e->stats != stats) - continue; - - /* set counters zero */ - e->last_conns = 0; - e->last_inpkts = 0; - e->last_outpkts = 0; - e->last_inbytes = 0; - e->last_outbytes = 0; - e->cps = 0; - e->inpps = 0; - e->outpps = 0; - e->inbps = 0; - e->outbps = 0; - } - write_unlock_bh(&est_lock); + struct ip_vs_estimator *est = &stats->est; + + /* set counters zero, caller must hold the stats->lock lock */ + est->last_inbytes = 0; + est->last_outbytes = 0; + est->last_conns = 0; + est->last_inpkts = 0; + est->last_outpkts = 0; + est->cps = 0; + est->inpps = 0; + est->outpps = 0; + est->inbps = 0; + est->outbps = 0; } -- cgit v1.2.3