diff options
| -rw-r--r-- | include/linux/netfilter/x_tables.h | 96 | ||||
| -rw-r--r-- | net/ipv4/netfilter/arp_tables.c | 18 | ||||
| -rw-r--r-- | net/ipv4/netfilter/ip_tables.c | 28 | ||||
| -rw-r--r-- | net/ipv6/netfilter/ip6_tables.c | 19 | ||||
| -rw-r--r-- | net/netfilter/x_tables.c | 9 |
5 files changed, 80 insertions, 90 deletions
diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h index 37219525ff6f..32cddf78b13e 100644 --- a/include/linux/netfilter/x_tables.h +++ b/include/linux/netfilter/x_tables.h @@ -456,72 +456,60 @@ extern void xt_proto_fini(struct net *net, u_int8_t af); extern struct xt_table_info *xt_alloc_table_info(unsigned int size); extern void xt_free_table_info(struct xt_table_info *info); -/* - * Per-CPU spinlock associated with per-cpu table entries, and - * with a counter for the "reading" side that allows a recursive - * reader to avoid taking the lock and deadlocking. - * - * "reading" is used by ip/arp/ip6 tables rule processing which runs per-cpu. - * It needs to ensure that the rules are not being changed while the packet - * is being processed. In some cases, the read lock will be acquired - * twice on the same CPU; this is okay because of the count. - * - * "writing" is used when reading counters. - * During replace any readers that are using the old tables have to complete - * before freeing the old table. This is handled by the write locking - * necessary for reading the counters. +/** + * xt_recseq - recursive seqcount for netfilter use + * + * Packet processing changes the seqcount only if no recursion happened + * get_counters() can use read_seqcount_begin()/read_seqcount_retry(), + * because we use the normal seqcount convention : + * Low order bit set to 1 if a writer is active. */ -struct xt_info_lock { - seqlock_t lock; - unsigned char readers; -}; -DECLARE_PER_CPU(struct xt_info_lock, xt_info_locks); +DECLARE_PER_CPU(seqcount_t, xt_recseq); -/* - * Note: we need to ensure that preemption is disabled before acquiring - * the per-cpu-variable, so we do it as a two step process rather than - * using "spin_lock_bh()". - * - * We _also_ need to disable bottom half processing before updating our - * nesting count, to make sure that the only kind of re-entrancy is this - * code being called by itself: since the count+lock is not an atomic - * operation, we can allow no races. +/** + * xt_write_recseq_begin - start of a write section * - * _Only_ that special combination of being per-cpu and never getting - * re-entered asynchronously means that the count is safe. + * Begin packet processing : all readers must wait the end + * 1) Must be called with preemption disabled + * 2) softirqs must be disabled too (or we should use irqsafe_cpu_add()) + * Returns : + * 1 if no recursion on this cpu + * 0 if recursion detected */ -static inline void xt_info_rdlock_bh(void) +static inline unsigned int xt_write_recseq_begin(void) { - struct xt_info_lock *lock; + unsigned int addend; - local_bh_disable(); - lock = &__get_cpu_var(xt_info_locks); - if (likely(!lock->readers++)) - write_seqlock(&lock->lock); -} + /* + * Low order bit of sequence is set if we already + * called xt_write_recseq_begin(). + */ + addend = (__this_cpu_read(xt_recseq.sequence) + 1) & 1; -static inline void xt_info_rdunlock_bh(void) -{ - struct xt_info_lock *lock = &__get_cpu_var(xt_info_locks); + /* + * This is kind of a write_seqcount_begin(), but addend is 0 or 1 + * We dont check addend value to avoid a test and conditional jump, + * since addend is most likely 1 + */ + __this_cpu_add(xt_recseq.sequence, addend); + smp_wmb(); - if (likely(!--lock->readers)) - write_sequnlock(&lock->lock); - local_bh_enable(); + return addend; } -/* - * The "writer" side needs to get exclusive access to the lock, - * regardless of readers. This must be called with bottom half - * processing (and thus also preemption) disabled. +/** + * xt_write_recseq_end - end of a write section + * @addend: return value from previous xt_write_recseq_begin() + * + * End packet processing : all readers can proceed + * 1) Must be called with preemption disabled + * 2) softirqs must be disabled too (or we should use irqsafe_cpu_add()) */ -static inline void xt_info_wrlock(unsigned int cpu) -{ - write_seqlock(&per_cpu(xt_info_locks, cpu).lock); -} - -static inline void xt_info_wrunlock(unsigned int cpu) +static inline void xt_write_recseq_end(unsigned int addend) { - write_sequnlock(&per_cpu(xt_info_locks, cpu).lock); + /* this is kind of a write_seqcount_end(), but addend is 0 or 1 */ + smp_wmb(); + __this_cpu_add(xt_recseq.sequence, addend); } /* diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index 4b5d457c2d76..2ea743336836 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -260,6 +260,7 @@ unsigned int arpt_do_table(struct sk_buff *skb, void *table_base; const struct xt_table_info *private; struct xt_action_param acpar; + unsigned int addend; if (!pskb_may_pull(skb, arp_hdr_len(skb->dev))) return NF_DROP; @@ -267,7 +268,8 @@ unsigned int arpt_do_table(struct sk_buff *skb, indev = in ? in->name : nulldevname; outdev = out ? out->name : nulldevname; - xt_info_rdlock_bh(); + local_bh_disable(); + addend = xt_write_recseq_begin(); private = table->private; table_base = private->entries[smp_processor_id()]; @@ -338,7 +340,8 @@ unsigned int arpt_do_table(struct sk_buff *skb, /* Verdict */ break; } while (!acpar.hotdrop); - xt_info_rdunlock_bh(); + xt_write_recseq_end(addend); + local_bh_enable(); if (acpar.hotdrop) return NF_DROP; @@ -712,7 +715,7 @@ static void get_counters(const struct xt_table_info *t, unsigned int i; for_each_possible_cpu(cpu) { - seqlock_t *lock = &per_cpu(xt_info_locks, cpu).lock; + seqcount_t *s = &per_cpu(xt_recseq, cpu); i = 0; xt_entry_foreach(iter, t->entries[cpu], t->size) { @@ -720,10 +723,10 @@ static void get_counters(const struct xt_table_info *t, unsigned int start; do { - start = read_seqbegin(lock); + start = read_seqcount_begin(s); bcnt = iter->counters.bcnt; pcnt = iter->counters.pcnt; - } while (read_seqretry(lock, start)); + } while (read_seqcount_retry(s, start)); ADD_COUNTER(counters[i], bcnt, pcnt); ++i; @@ -1115,6 +1118,7 @@ static int do_add_counters(struct net *net, const void __user *user, int ret = 0; void *loc_cpu_entry; struct arpt_entry *iter; + unsigned int addend; #ifdef CONFIG_COMPAT struct compat_xt_counters_info compat_tmp; @@ -1171,12 +1175,12 @@ static int do_add_counters(struct net *net, const void __user *user, /* Choose the copy that is on our node */ curcpu = smp_processor_id(); loc_cpu_entry = private->entries[curcpu]; - xt_info_wrlock(curcpu); + addend = xt_write_recseq_begin(); xt_entry_foreach(iter, loc_cpu_entry, private->size) { ADD_COUNTER(iter->counters, paddc[i].bcnt, paddc[i].pcnt); ++i; } - xt_info_wrunlock(curcpu); + xt_write_recseq_end(addend); unlock_up_free: local_bh_enable(); xt_table_unlock(t); diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index ffcea0d1678e..2b6b700949eb 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -68,15 +68,6 @@ void *ipt_alloc_initial_table(const struct xt_table *info) } EXPORT_SYMBOL_GPL(ipt_alloc_initial_table); -/* - We keep a set of rules for each CPU, so we can avoid write-locking - them in the softirq when updating the counters and therefore - only need to read-lock in the softirq; doing a write_lock_bh() in user - context stops packets coming through and allows user context to read - the counters or update the rules. - - Hence the start of any table is given by get_table() below. */ - /* Returns whether matches rule or not. */ /* Performance critical - called for every packet */ static inline bool @@ -311,6 +302,7 @@ ipt_do_table(struct sk_buff *skb, unsigned int *stackptr, origptr, cpu; const struct xt_table_info *private; struct xt_action_param acpar; + unsigned int addend; /* Initialization */ ip = ip_hdr(skb); @@ -331,7 +323,8 @@ ipt_do_table(struct sk_buff *skb, acpar.hooknum = hook; IP_NF_ASSERT(table->valid_hooks & (1 << hook)); - xt_info_rdlock_bh(); + local_bh_disable(); + addend = xt_write_recseq_begin(); private = table->private; cpu = smp_processor_id(); table_base = private->entries[cpu]; @@ -430,7 +423,9 @@ ipt_do_table(struct sk_buff *skb, pr_debug("Exiting %s; resetting sp from %u to %u\n", __func__, *stackptr, origptr); *stackptr = origptr; - xt_info_rdunlock_bh(); + xt_write_recseq_end(addend); + local_bh_enable(); + #ifdef DEBUG_ALLOW_ALL return NF_ACCEPT; #else @@ -886,7 +881,7 @@ get_counters(const struct xt_table_info *t, unsigned int i; for_each_possible_cpu(cpu) { - seqlock_t *lock = &per_cpu(xt_info_locks, cpu).lock; + seqcount_t *s = &per_cpu(xt_recseq, cpu); i = 0; xt_entry_foreach(iter, t->entries[cpu], t->size) { @@ -894,10 +889,10 @@ get_counters(const struct xt_table_info *t, unsigned int start; do { - start = read_seqbegin(lock); + start = read_seqcount_begin(s); bcnt = iter->counters.bcnt; pcnt = iter->counters.pcnt; - } while (read_seqretry(lock, start)); + } while (read_seqcount_retry(s, start)); ADD_COUNTER(counters[i], bcnt, pcnt); ++i; /* macro does multi eval of i */ @@ -1312,6 +1307,7 @@ do_add_counters(struct net *net, const void __user *user, int ret = 0; void *loc_cpu_entry; struct ipt_entry *iter; + unsigned int addend; #ifdef CONFIG_COMPAT struct compat_xt_counters_info compat_tmp; @@ -1368,12 +1364,12 @@ do_add_counters(struct net *net, const void __user *user, /* Choose the copy that is on our node */ curcpu = smp_processor_id(); loc_cpu_entry = private->entries[curcpu]; - xt_info_wrlock(curcpu); + addend = xt_write_recseq_begin(); xt_entry_foreach(iter, loc_cpu_entry, private->size) { ADD_COUNTER(iter->counters, paddc[i].bcnt, paddc[i].pcnt); ++i; } - xt_info_wrunlock(curcpu); + xt_write_recseq_end(addend); unlock_up_free: local_bh_enable(); xt_table_unlock(t); diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index 0b2af9b85cec..ec7cf579cdd4 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -340,6 +340,7 @@ ip6t_do_table(struct sk_buff *skb, unsigned int *stackptr, origptr, cpu; const struct xt_table_info *private; struct xt_action_param acpar; + unsigned int addend; /* Initialization */ indev = in ? in->name : nulldevname; @@ -358,7 +359,8 @@ ip6t_do_table(struct sk_buff *skb, IP_NF_ASSERT(table->valid_hooks & (1 << hook)); - xt_info_rdlock_bh(); + local_bh_disable(); + addend = xt_write_recseq_begin(); private = table->private; cpu = smp_processor_id(); table_base = private->entries[cpu]; @@ -442,7 +444,9 @@ ip6t_do_table(struct sk_buff *skb, } while (!acpar.hotdrop); *stackptr = origptr; - xt_info_rdunlock_bh(); + + xt_write_recseq_end(addend); + local_bh_enable(); #ifdef DEBUG_ALLOW_ALL return NF_ACCEPT; @@ -899,7 +903,7 @@ get_counters(const struct xt_table_info *t, unsigned int i; for_each_possible_cpu(cpu) { - seqlock_t *lock = &per_cpu(xt_info_locks, cpu).lock; + seqcount_t *s = &per_cpu(xt_recseq, cpu); i = 0; xt_entry_foreach(iter, t->entries[cpu], t->size) { @@ -907,10 +911,10 @@ get_counters(const struct xt_table_info *t, unsigned int start; do { - start = read_seqbegin(lock); + start = read_seqcount_begin(s); bcnt = iter->counters.bcnt; pcnt = iter->counters.pcnt; - } while (read_seqretry(lock, start)); + } while (read_seqcount_retry(s, start)); ADD_COUNTER(counters[i], bcnt, pcnt); ++i; @@ -1325,6 +1329,7 @@ do_add_counters(struct net *net, const void __user *user, unsigned int len, int ret = 0; const void *loc_cpu_entry; struct ip6t_entry *iter; + unsigned int addend; #ifdef CONFIG_COMPAT struct compat_xt_counters_info compat_tmp; @@ -1381,13 +1386,13 @@ do_add_counters(struct net *net, const void __user *user, unsigned int len, i = 0; /* Choose the copy that is on our node */ curcpu = smp_processor_id(); - xt_info_wrlock(curcpu); + addend = xt_write_recseq_begin(); loc_cpu_entry = private->entries[curcpu]; xt_entry_foreach(iter, loc_cpu_entry, private->size) { ADD_COUNTER(iter->counters, paddc[i].bcnt, paddc[i].pcnt); ++i; } - xt_info_wrunlock(curcpu); + xt_write_recseq_end(addend); unlock_up_free: local_bh_enable(); diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index a9adf4c6b299..52959efca858 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -762,8 +762,8 @@ void xt_compat_unlock(u_int8_t af) EXPORT_SYMBOL_GPL(xt_compat_unlock); #endif -DEFINE_PER_CPU(struct xt_info_lock, xt_info_locks); -EXPORT_PER_CPU_SYMBOL_GPL(xt_info_locks); +DEFINE_PER_CPU(seqcount_t, xt_recseq); +EXPORT_PER_CPU_SYMBOL_GPL(xt_recseq); static int xt_jumpstack_alloc(struct xt_table_info *i) { @@ -1362,10 +1362,7 @@ static int __init xt_init(void) int rv; for_each_possible_cpu(i) { - struct xt_info_lock *lock = &per_cpu(xt_info_locks, i); - - seqlock_init(&lock->lock); - lock->readers = 0; + seqcount_init(&per_cpu(xt_recseq, i)); } xt = kmalloc(sizeof(struct xt_af) * NFPROTO_NUMPROTO, GFP_KERNEL); |