* Re: [PATCH 37/50] netfilter: nf_tables: atomic dump and reset for stateful objects
[not found] ` <1481147576-5690-38-git-send-email-pablo@netfilter.org>
@ 2016-12-09 0:40 ` Paul Gortmaker
2016-12-09 10:24 ` Pablo Neira Ayuso
0 siblings, 1 reply; 5+ messages in thread
From: Paul Gortmaker @ 2016-12-09 0:40 UTC (permalink / raw)
To: Pablo Neira Ayuso; +Cc: netfilter-devel, David Miller, netdev, linux-next
On Wed, Dec 7, 2016 at 4:52 PM, Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> This patch adds a new NFT_MSG_GETOBJ_RESET command perform an atomic
> dump-and-reset of the stateful object. This also comes with add support
> for atomic dump and reset for counter and quota objects.
This triggered a new build failure in linux-next on parisc-32, which a
hands-off bisect
run lists as resulting from this:
ERROR: "__cmpxchg_u64" [net/netfilter/nft_counter.ko] undefined!
make[2]: *** [__modpost] Error 1
make[1]: *** [modules] Error 2
make: *** [sub-make] Error 2
43da04a593d8b2626f1cf4b56efe9402f6b53652 is the first bad commit
commit 43da04a593d8b2626f1cf4b56efe9402f6b53652
Author: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Mon Nov 28 00:05:44 2016 +0100
netfilter: nf_tables: atomic dump and reset for stateful objects
This patch adds a new NFT_MSG_GETOBJ_RESET command perform an atomic
dump-and-reset of the stateful object. This also comes with add support
for atomic dump and reset for counter and quota objects.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
:040000 040000 6cd4554f69247e5c837db52342f26888beda1623
5908aca93c89e7922336546c3753bfcf2aceefba M include
:040000 040000 f25d5831eb30972436bd198c5bb237a0cb0b4856
4ee5751c8de02bb5a8dcaadb2a2df7986d90f8e9 M net
bisect run success
Guessing this is more an issue with parisc than it is with netfilter, but I
figured I'd mention it anyway.
Paul.
--
>
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> ---
> include/net/netfilter/nf_tables.h | 3 +-
> include/uapi/linux/netfilter/nf_tables.h | 2 ++
> net/netfilter/nf_tables_api.c | 29 ++++++++++++-----
> net/netfilter/nft_counter.c | 56 +++++++++++++++++++++++++++-----
> net/netfilter/nft_quota.c | 18 ++++++----
> 5 files changed, 85 insertions(+), 23 deletions(-)
>
> diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
> index 903cd618f50e..6f7d6a1dc09c 100644
> --- a/include/net/netfilter/nf_tables.h
> +++ b/include/net/netfilter/nf_tables.h
> @@ -997,7 +997,8 @@ struct nft_object_type {
> struct nft_object *obj);
> void (*destroy)(struct nft_object *obj);
> int (*dump)(struct sk_buff *skb,
> - const struct nft_object *obj);
> + struct nft_object *obj,
> + bool reset);
> };
>
> int nft_register_obj(struct nft_object_type *obj_type);
> diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
> index 3d47582caa80..399eac1eee91 100644
> --- a/include/uapi/linux/netfilter/nf_tables.h
> +++ b/include/uapi/linux/netfilter/nf_tables.h
> @@ -89,6 +89,7 @@ enum nft_verdicts {
> * @NFT_MSG_NEWOBJ: create a stateful object (enum nft_obj_attributes)
> * @NFT_MSG_GETOBJ: get a stateful object (enum nft_obj_attributes)
> * @NFT_MSG_DELOBJ: delete a stateful object (enum nft_obj_attributes)
> + * @NFT_MSG_GETOBJ_RESET: get and reset a stateful object (enum nft_obj_attributes)
> */
> enum nf_tables_msg_types {
> NFT_MSG_NEWTABLE,
> @@ -112,6 +113,7 @@ enum nf_tables_msg_types {
> NFT_MSG_NEWOBJ,
> NFT_MSG_GETOBJ,
> NFT_MSG_DELOBJ,
> + NFT_MSG_GETOBJ_RESET,
> NFT_MSG_MAX,
> };
>
> diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> index 2ae717c5dcb8..bfc015af366a 100644
> --- a/net/netfilter/nf_tables_api.c
> +++ b/net/netfilter/nf_tables_api.c
> @@ -3972,14 +3972,14 @@ static struct nft_object *nft_obj_init(const struct nft_object_type *type,
> }
>
> static int nft_object_dump(struct sk_buff *skb, unsigned int attr,
> - const struct nft_object *obj)
> + struct nft_object *obj, bool reset)
> {
> struct nlattr *nest;
>
> nest = nla_nest_start(skb, attr);
> if (!nest)
> goto nla_put_failure;
> - if (obj->type->dump(skb, obj) < 0)
> + if (obj->type->dump(skb, obj, reset) < 0)
> goto nla_put_failure;
> nla_nest_end(skb, nest);
> return 0;
> @@ -4096,7 +4096,7 @@ static int nf_tables_newobj(struct net *net, struct sock *nlsk,
> static int nf_tables_fill_obj_info(struct sk_buff *skb, struct net *net,
> u32 portid, u32 seq, int event, u32 flags,
> int family, const struct nft_table *table,
> - const struct nft_object *obj)
> + struct nft_object *obj, bool reset)
> {
> struct nfgenmsg *nfmsg;
> struct nlmsghdr *nlh;
> @@ -4115,7 +4115,7 @@ static int nf_tables_fill_obj_info(struct sk_buff *skb, struct net *net,
> nla_put_string(skb, NFTA_OBJ_NAME, obj->name) ||
> nla_put_be32(skb, NFTA_OBJ_TYPE, htonl(obj->type->type)) ||
> nla_put_be32(skb, NFTA_OBJ_USE, htonl(obj->use)) ||
> - nft_object_dump(skb, NFTA_OBJ_DATA, obj))
> + nft_object_dump(skb, NFTA_OBJ_DATA, obj, reset))
> goto nla_put_failure;
>
> nlmsg_end(skb, nlh);
> @@ -4131,10 +4131,14 @@ static int nf_tables_dump_obj(struct sk_buff *skb, struct netlink_callback *cb)
> const struct nfgenmsg *nfmsg = nlmsg_data(cb->nlh);
> const struct nft_af_info *afi;
> const struct nft_table *table;
> - const struct nft_object *obj;
> unsigned int idx = 0, s_idx = cb->args[0];
> struct net *net = sock_net(skb->sk);
> int family = nfmsg->nfgen_family;
> + struct nft_object *obj;
> + bool reset = false;
> +
> + if (NFNL_MSG_TYPE(cb->nlh->nlmsg_type) == NFT_MSG_GETOBJ_RESET)
> + reset = true;
>
> rcu_read_lock();
> cb->seq = net->nft.base_seq;
> @@ -4156,7 +4160,7 @@ static int nf_tables_dump_obj(struct sk_buff *skb, struct netlink_callback *cb)
> cb->nlh->nlmsg_seq,
> NFT_MSG_NEWOBJ,
> NLM_F_MULTI | NLM_F_APPEND,
> - afi->family, table, obj) < 0)
> + afi->family, table, obj, reset) < 0)
> goto done;
>
> nl_dump_check_consistent(cb, nlmsg_hdr(skb));
> @@ -4183,6 +4187,7 @@ static int nf_tables_getobj(struct net *net, struct sock *nlsk,
> const struct nft_table *table;
> struct nft_object *obj;
> struct sk_buff *skb2;
> + bool reset = false;
> u32 objtype;
> int err;
>
> @@ -4214,9 +4219,12 @@ static int nf_tables_getobj(struct net *net, struct sock *nlsk,
> if (!skb2)
> return -ENOMEM;
>
> + if (NFNL_MSG_TYPE(nlh->nlmsg_type) == NFT_MSG_GETOBJ_RESET)
> + reset = true;
> +
> err = nf_tables_fill_obj_info(skb2, net, NETLINK_CB(skb).portid,
> nlh->nlmsg_seq, NFT_MSG_NEWOBJ, 0,
> - family, table, obj);
> + family, table, obj, reset);
> if (err < 0)
> goto err;
>
> @@ -4291,7 +4299,7 @@ static int nf_tables_obj_notify(const struct nft_ctx *ctx,
>
> err = nf_tables_fill_obj_info(skb, ctx->net, ctx->portid, ctx->seq,
> event, 0, ctx->afi->family, ctx->table,
> - obj);
> + obj, false);
> if (err < 0) {
> kfree_skb(skb);
> goto err;
> @@ -4482,6 +4490,11 @@ static const struct nfnl_callback nf_tables_cb[NFT_MSG_MAX] = {
> .attr_count = NFTA_OBJ_MAX,
> .policy = nft_obj_policy,
> },
> + [NFT_MSG_GETOBJ_RESET] = {
> + .call = nf_tables_getobj,
> + .attr_count = NFTA_OBJ_MAX,
> + .policy = nft_obj_policy,
> + },
> };
>
> static void nft_chain_commit_update(struct nft_trans *trans)
> diff --git a/net/netfilter/nft_counter.c b/net/netfilter/nft_counter.c
> index 6f3dd429f865..f6a02c5071c2 100644
> --- a/net/netfilter/nft_counter.c
> +++ b/net/netfilter/nft_counter.c
> @@ -100,10 +100,10 @@ static void nft_counter_obj_destroy(struct nft_object *obj)
> nft_counter_do_destroy(priv);
> }
>
> -static void nft_counter_fetch(const struct nft_counter_percpu __percpu *counter,
> +static void nft_counter_fetch(struct nft_counter_percpu __percpu *counter,
> struct nft_counter *total)
> {
> - const struct nft_counter_percpu *cpu_stats;
> + struct nft_counter_percpu *cpu_stats;
> u64 bytes, packets;
> unsigned int seq;
> int cpu;
> @@ -122,12 +122,52 @@ static void nft_counter_fetch(const struct nft_counter_percpu __percpu *counter,
> }
> }
>
> +static u64 __nft_counter_reset(u64 *counter)
> +{
> + u64 ret, old;
> +
> + do {
> + old = *counter;
> + ret = cmpxchg64(counter, old, 0);
> + } while (ret != old);
> +
> + return ret;
> +}
> +
> +static void nft_counter_reset(struct nft_counter_percpu __percpu *counter,
> + struct nft_counter *total)
> +{
> + struct nft_counter_percpu *cpu_stats;
> + u64 bytes, packets;
> + unsigned int seq;
> + int cpu;
> +
> + memset(total, 0, sizeof(*total));
> + for_each_possible_cpu(cpu) {
> + bytes = packets = 0;
> +
> + cpu_stats = per_cpu_ptr(counter, cpu);
> + do {
> + seq = u64_stats_fetch_begin_irq(&cpu_stats->syncp);
> + packets += __nft_counter_reset(&cpu_stats->counter.packets);
> + bytes += __nft_counter_reset(&cpu_stats->counter.bytes);
> + } while (u64_stats_fetch_retry_irq(&cpu_stats->syncp, seq));
> +
> + total->packets += packets;
> + total->bytes += bytes;
> + }
> +}
> +
> static int nft_counter_do_dump(struct sk_buff *skb,
> - const struct nft_counter_percpu_priv *priv)
> + const struct nft_counter_percpu_priv *priv,
> + bool reset)
> {
> struct nft_counter total;
>
> - nft_counter_fetch(priv->counter, &total);
> + if (reset)
> + nft_counter_reset(priv->counter, &total);
> + else
> + nft_counter_fetch(priv->counter, &total);
>
> if (nla_put_be64(skb, NFTA_COUNTER_BYTES, cpu_to_be64(total.bytes),
> NFTA_COUNTER_PAD) ||
> @@ -141,11 +181,11 @@ static int nft_counter_do_dump(struct sk_buff *skb,
> }
>
> static int nft_counter_obj_dump(struct sk_buff *skb,
> - const struct nft_object *obj)
> + struct nft_object *obj, bool reset)
> {
> - const struct nft_counter_percpu_priv *priv = nft_obj_data(obj);
> + struct nft_counter_percpu_priv *priv = nft_obj_data(obj);
>
> - return nft_counter_do_dump(skb, priv);
> + return nft_counter_do_dump(skb, priv, reset);
> }
>
> static const struct nla_policy nft_counter_policy[NFTA_COUNTER_MAX + 1] = {
> @@ -178,7 +218,7 @@ static int nft_counter_dump(struct sk_buff *skb, const struct nft_expr *expr)
> {
> const struct nft_counter_percpu_priv *priv = nft_expr_priv(expr);
>
> - return nft_counter_do_dump(skb, priv);
> + return nft_counter_do_dump(skb, priv, false);
> }
>
> static int nft_counter_init(const struct nft_ctx *ctx,
> diff --git a/net/netfilter/nft_quota.c b/net/netfilter/nft_quota.c
> index 0d344209803a..5d25f57497cb 100644
> --- a/net/netfilter/nft_quota.c
> +++ b/net/netfilter/nft_quota.c
> @@ -83,12 +83,17 @@ static int nft_quota_obj_init(const struct nlattr * const tb[],
> return nft_quota_do_init(tb, priv);
> }
>
> -static int nft_quota_do_dump(struct sk_buff *skb, const struct nft_quota *priv)
> +static int nft_quota_do_dump(struct sk_buff *skb, struct nft_quota *priv,
> + bool reset)
> {
> u32 flags = priv->invert ? NFT_QUOTA_F_INV : 0;
> u64 consumed;
>
> - consumed = atomic64_read(&priv->consumed);
> + if (reset)
> + consumed = atomic64_xchg(&priv->consumed, 0);
> + else
> + consumed = atomic64_read(&priv->consumed);
> +
> /* Since we inconditionally increment consumed quota for each packet
> * that we see, don't go over the quota boundary in what we send to
> * userspace.
> @@ -108,11 +113,12 @@ static int nft_quota_do_dump(struct sk_buff *skb, const struct nft_quota *priv)
> return -1;
> }
>
> -static int nft_quota_obj_dump(struct sk_buff *skb, const struct nft_object *obj)
> +static int nft_quota_obj_dump(struct sk_buff *skb, struct nft_object *obj,
> + bool reset)
> {
> struct nft_quota *priv = nft_obj_data(obj);
>
> - return nft_quota_do_dump(skb, priv);
> + return nft_quota_do_dump(skb, priv, reset);
> }
>
> static struct nft_object_type nft_quota_obj __read_mostly = {
> @@ -146,9 +152,9 @@ static int nft_quota_init(const struct nft_ctx *ctx,
>
> static int nft_quota_dump(struct sk_buff *skb, const struct nft_expr *expr)
> {
> - const struct nft_quota *priv = nft_expr_priv(expr);
> + struct nft_quota *priv = nft_expr_priv(expr);
>
> - return nft_quota_do_dump(skb, priv);
> + return nft_quota_do_dump(skb, priv, false);
> }
>
> static struct nft_expr_type nft_quota_type;
> --
> 2.1.4
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 37/50] netfilter: nf_tables: atomic dump and reset for stateful objects
2016-12-09 0:40 ` [PATCH 37/50] netfilter: nf_tables: atomic dump and reset for stateful objects Paul Gortmaker
@ 2016-12-09 10:24 ` Pablo Neira Ayuso
2016-12-09 14:24 ` Eric Dumazet
0 siblings, 1 reply; 5+ messages in thread
From: Pablo Neira Ayuso @ 2016-12-09 10:24 UTC (permalink / raw)
To: Paul Gortmaker; +Cc: netfilter-devel, David Miller, netdev, linux-next
[-- Attachment #1: Type: text/plain, Size: 1674 bytes --]
Hi Paul,
On Thu, Dec 08, 2016 at 07:40:14PM -0500, Paul Gortmaker wrote:
> On Wed, Dec 7, 2016 at 4:52 PM, Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > This patch adds a new NFT_MSG_GETOBJ_RESET command perform an atomic
> > dump-and-reset of the stateful object. This also comes with add support
> > for atomic dump and reset for counter and quota objects.
>
> This triggered a new build failure in linux-next on parisc-32, which a
> hands-off bisect
> run lists as resulting from this:
>
> ERROR: "__cmpxchg_u64" [net/netfilter/nft_counter.ko] undefined!
> make[2]: *** [__modpost] Error 1
> make[1]: *** [modules] Error 2
> make: *** [sub-make] Error 2
> 43da04a593d8b2626f1cf4b56efe9402f6b53652 is the first bad commit
> commit 43da04a593d8b2626f1cf4b56efe9402f6b53652
> Author: Pablo Neira Ayuso <pablo@netfilter.org>
> Date: Mon Nov 28 00:05:44 2016 +0100
>
> netfilter: nf_tables: atomic dump and reset for stateful objects
>
> This patch adds a new NFT_MSG_GETOBJ_RESET command perform an atomic
> dump-and-reset of the stateful object. This also comes with add support
> for atomic dump and reset for counter and quota objects.
>
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
>
> :040000 040000 6cd4554f69247e5c837db52342f26888beda1623
> 5908aca93c89e7922336546c3753bfcf2aceefba M include
> :040000 040000 f25d5831eb30972436bd198c5bb237a0cb0b4856
> 4ee5751c8de02bb5a8dcaadb2a2df7986d90f8e9 M net
> bisect run success
>
> Guessing this is more an issue with parisc than it is with netfilter, but I
> figured I'd mention it anyway.
I'm planning to submit this patch to parisc, I'm attaching it to this
email.
[-- Attachment #2: 0001-parisc-export-symbol-__cmpxchg_u64.patch --]
[-- Type: text/x-diff, Size: 1313 bytes --]
>From c9d320ac0be2a32a7b2bfad398be549865088ecf Mon Sep 17 00:00:00 2001
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Thu, 8 Dec 2016 22:55:33 +0100
Subject: [PATCH] parisc: export symbol __cmpxchg_u64()
kbuild test robot reports:
>> ERROR: "__cmpxchg_u64" [net/netfilter/nft_counter.ko] undefined!
Commit 43da04a593d8 ("netfilter: nf_tables: atomic dump and reset for
stateful objects") introduces the first client of cmpxchg64() from
modules.
Patch 54b668009076 ("parisc: Add native high-resolution sched_clock()
implementation") removed __cmpxchg_u64() dependency on CONFIG_64BIT.
So, let's fix this problem by exporting this symbol unconditionally.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
arch/parisc/kernel/parisc_ksyms.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/parisc/kernel/parisc_ksyms.c b/arch/parisc/kernel/parisc_ksyms.c
index 3cad8aadc69e..cfa704548cf3 100644
--- a/arch/parisc/kernel/parisc_ksyms.c
+++ b/arch/parisc/kernel/parisc_ksyms.c
@@ -40,8 +40,8 @@ EXPORT_SYMBOL(__atomic_hash);
#endif
#ifdef CONFIG_64BIT
EXPORT_SYMBOL(__xchg64);
-EXPORT_SYMBOL(__cmpxchg_u64);
#endif
+EXPORT_SYMBOL(__cmpxchg_u64);
#include <asm/uaccess.h>
EXPORT_SYMBOL(lclear_user);
--
2.1.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 37/50] netfilter: nf_tables: atomic dump and reset for stateful objects
2016-12-09 10:24 ` Pablo Neira Ayuso
@ 2016-12-09 14:24 ` Eric Dumazet
2016-12-09 15:22 ` Eric Dumazet
0 siblings, 1 reply; 5+ messages in thread
From: Eric Dumazet @ 2016-12-09 14:24 UTC (permalink / raw)
To: Pablo Neira Ayuso
Cc: Paul Gortmaker, netfilter-devel, David Miller, netdev, linux-next
On Fri, 2016-12-09 at 11:24 +0100, Pablo Neira Ayuso wrote:
> Hi Paul,
Hi Pablo
Given that bytes/packets counters are modified without cmpxchg64() :
static inline void nft_counter_do_eval(struct nft_counter_percpu_priv *priv,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_counter_percpu *this_cpu;
local_bh_disable();
this_cpu = this_cpu_ptr(priv->counter);
u64_stats_update_begin(&this_cpu->syncp);
this_cpu->counter.bytes += pkt->skb->len;
this_cpu->counter.packets++;
u64_stats_update_end(&this_cpu->syncp);
local_bh_enable();
}
It means that the cmpxchg64() used to clear the stats is not good enough.
It does not help to make sure stats are properly cleared.
On 64 bit, the ->syncp is not there, so the nft_counter_reset() might
not see that a bytes or packets counter was modified by another cpu.
CPU 1 CPU 2
LOAD PTR->BYTES into REG_A old = *counter;
REG_A += skb->len;
cmpxchg64(counter, old, 0);
PTR->BYTES = REG_A
It looks that you want a seqcount, even on 64bit arches,
so that CPU 2 can restart its loop, and more importantly you need
to not accumulate the values you read, because they might be old/invalid.
Another way would be to not use cmpxchg64() at all.
Way to expensive in fast path !
The percpu value would never be modified by an other cpu than the owner.
You need a per cpu seqcount, no need to add a syncp per nft percpu counter.
static DEFINE_PERCPU(seqcount_t, nft_pcpu_seq);
static inline void nft_counter_do_eval(struct nft_counter_percpu_priv *priv,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_counter_percpu *this_cpu;
seqcount_t *myseq;
local_bh_disable();
this_cpu = this_cpu_ptr(priv->counter);
myseq = this_cpu_ptr(&nft_pcpu_seq);
write_seqcount_begin(myseq);
this_cpu->counter.bytes += pkt->skb->len;
this_cpu->counter.packets++;
write_seqcount_end(myseq);
local_bh_enable();
}
Thanks !
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 37/50] netfilter: nf_tables: atomic dump and reset for stateful objects
2016-12-09 14:24 ` Eric Dumazet
@ 2016-12-09 15:22 ` Eric Dumazet
2016-12-10 12:21 ` Pablo Neira Ayuso
0 siblings, 1 reply; 5+ messages in thread
From: Eric Dumazet @ 2016-12-09 15:22 UTC (permalink / raw)
To: Pablo Neira Ayuso
Cc: Paul Gortmaker, netfilter-devel, David Miller, netdev, linux-next
On Fri, 2016-12-09 at 06:24 -0800, Eric Dumazet wrote:
> It looks that you want a seqcount, even on 64bit arches,
> so that CPU 2 can restart its loop, and more importantly you need
> to not accumulate the values you read, because they might be old/invalid.
Untested patch to give general idea. I can polish it a bit later today.
net/netfilter/nft_counter.c | 59 +++++++++++++---------------------
1 file changed, 23 insertions(+), 36 deletions(-)
diff --git a/net/netfilter/nft_counter.c b/net/netfilter/nft_counter.c
index f6a02c5071c2aeafca7635da3282a809aa04d6ab..57ed95b024473a2aa76298fe5bb5013bf709801b 100644
--- a/net/netfilter/nft_counter.c
+++ b/net/netfilter/nft_counter.c
@@ -31,18 +31,25 @@ struct nft_counter_percpu_priv {
struct nft_counter_percpu __percpu *counter;
};
+static DEFINE_PER_CPU(seqcount_t, nft_counter_seq);
+
static inline void nft_counter_do_eval(struct nft_counter_percpu_priv *priv,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_counter_percpu *this_cpu;
+ seqcount_t *myseq;
local_bh_disable();
this_cpu = this_cpu_ptr(priv->counter);
- u64_stats_update_begin(&this_cpu->syncp);
+ myseq = this_cpu_ptr(&nft_counter_seq);
+
+ write_seqcount_begin(myseq);
+
this_cpu->counter.bytes += pkt->skb->len;
this_cpu->counter.packets++;
- u64_stats_update_end(&this_cpu->syncp);
+
+ write_seqcount_end(myseq);
local_bh_enable();
}
@@ -110,52 +117,30 @@ static void nft_counter_fetch(struct nft_counter_percpu __percpu *counter,
memset(total, 0, sizeof(*total));
for_each_possible_cpu(cpu) {
+ seqcount_t *seqp = per_cpu_ptr(&nft_counter_seq, cpu);
+
cpu_stats = per_cpu_ptr(counter, cpu);
do {
- seq = u64_stats_fetch_begin_irq(&cpu_stats->syncp);
+ seq = read_seqcount_begin(seqp);
bytes = cpu_stats->counter.bytes;
packets = cpu_stats->counter.packets;
- } while (u64_stats_fetch_retry_irq(&cpu_stats->syncp, seq));
+ } while (read_seqcount_retry(seqp, seq));
total->packets += packets;
total->bytes += bytes;
}
}
-static u64 __nft_counter_reset(u64 *counter)
-{
- u64 ret, old;
-
- do {
- old = *counter;
- ret = cmpxchg64(counter, old, 0);
- } while (ret != old);
-
- return ret;
-}
-
static void nft_counter_reset(struct nft_counter_percpu __percpu *counter,
struct nft_counter *total)
{
struct nft_counter_percpu *cpu_stats;
- u64 bytes, packets;
- unsigned int seq;
- int cpu;
- memset(total, 0, sizeof(*total));
- for_each_possible_cpu(cpu) {
- bytes = packets = 0;
-
- cpu_stats = per_cpu_ptr(counter, cpu);
- do {
- seq = u64_stats_fetch_begin_irq(&cpu_stats->syncp);
- packets += __nft_counter_reset(&cpu_stats->counter.packets);
- bytes += __nft_counter_reset(&cpu_stats->counter.bytes);
- } while (u64_stats_fetch_retry_irq(&cpu_stats->syncp, seq));
-
- total->packets += packets;
- total->bytes += bytes;
- }
+ local_bh_disable();
+ cpu_stats = this_cpu_ptr(counter);
+ cpu_stats->counter.packets -= total->packets;
+ cpu_stats->counter.bytes -= total->bytes;
+ local_bh_enable();
}
static int nft_counter_do_dump(struct sk_buff *skb,
@@ -164,10 +149,9 @@ static int nft_counter_do_dump(struct sk_buff *skb,
{
struct nft_counter total;
+ nft_counter_fetch(priv->counter, &total);
if (reset)
nft_counter_reset(priv->counter, &total);
- else
- nft_counter_fetch(priv->counter, &total);
if (nla_put_be64(skb, NFTA_COUNTER_BYTES, cpu_to_be64(total.bytes),
NFTA_COUNTER_PAD) ||
@@ -285,7 +269,10 @@ static struct nft_expr_type nft_counter_type __read_mostly = {
static int __init nft_counter_module_init(void)
{
- int err;
+ int err, cpu;
+
+ for_each_possible_cpu(cpu)
+ seqcount_init(per_cpu_ptr(&nft_counter_seq, cpu));
err = nft_register_obj(&nft_counter_obj);
if (err < 0)
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 37/50] netfilter: nf_tables: atomic dump and reset for stateful objects
2016-12-09 15:22 ` Eric Dumazet
@ 2016-12-10 12:21 ` Pablo Neira Ayuso
0 siblings, 0 replies; 5+ messages in thread
From: Pablo Neira Ayuso @ 2016-12-10 12:21 UTC (permalink / raw)
To: Eric Dumazet
Cc: Paul Gortmaker, netfilter-devel, David Miller, netdev, linux-next
On Fri, Dec 09, 2016 at 07:22:06AM -0800, Eric Dumazet wrote:
> On Fri, 2016-12-09 at 06:24 -0800, Eric Dumazet wrote:
>
> > It looks that you want a seqcount, even on 64bit arches,
> > so that CPU 2 can restart its loop, and more importantly you need
> > to not accumulate the values you read, because they might be old/invalid.
>
> Untested patch to give general idea. I can polish it a bit later today.
I'm preparing a patch now, so you can review it.
Eric, thanks a lot for reviewing and proposing a working approach!
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2016-12-10 12:21 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2016-12-09 0:40 ` [PATCH 37/50] netfilter: nf_tables: atomic dump and reset for stateful objects Paul Gortmaker
2016-12-09 10:24 ` Pablo Neira Ayuso
2016-12-09 14:24 ` Eric Dumazet
2016-12-09 15:22 ` Eric Dumazet
2016-12-10 12:21 ` Pablo Neira Ayuso
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