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Message-Id: <20190904033408.13988-1-liuhangbin@gmail.com>
Date: Wed, 4 Sep 2019 11:34:08 +0800
From: Hangbin Liu <liuhangbin@...il.com>
To: netdev@...r.kernel.org
Cc: Phil Karn <karn@...q.net>,
Sukumar Gopalakrishnan <sukumarg1973@...il.com>,
"David S . Miller" <davem@...emloft.net>,
Alexey Kuznetsov <kuznet@....inr.ac.ru>,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
Hangbin Liu <liuhangbin@...il.com>
Subject: [PATCHv2 net-next] ipmr: remove cache_resolve_queue_len
This is a re-post of previous patch wrote by David Miller[1].
Phil Karn reported[2] that on busy networks with lots of unresolved
multicast routing entries, the creation of new multicast group routes
can be extremely slow and unreliable.
The reason is we hard-coded multicast route entries with unresolved source
addresses(cache_resolve_queue_len) to 10. If some multicast route never
resolves and the unresolved source addresses increased, there will
be no ability to create new multicast route cache.
To resolve this issue, we need either add a sysctl entry to make the
cache_resolve_queue_len configurable, or just remove cache_resolve_queue_len
directly, as we already have the socket receive queue limits of mrouted
socket, pointed by David.
>From my side, I'd perfer to remove the cache_resolve_queue_len instead
of creating two more(IPv4 and IPv6 version) sysctl entry.
[1] https://lkml.org/lkml/2018/7/22/11
[2] https://lkml.org/lkml/2018/7/21/343
v2: hold the mfc_unres_lock while walking the unresolved list in
queue_count(), as Nikolay Aleksandrov remind.
Reported-by: Phil Karn <karn@...q.net>
Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
---
include/linux/mroute_base.h | 2 --
net/ipv4/ipmr.c | 30 +++++++++++++++++++++---------
net/ipv6/ip6mr.c | 10 +++-------
3 files changed, 24 insertions(+), 18 deletions(-)
diff --git a/include/linux/mroute_base.h b/include/linux/mroute_base.h
index 34de06b426ef..50fb89533029 100644
--- a/include/linux/mroute_base.h
+++ b/include/linux/mroute_base.h
@@ -235,7 +235,6 @@ struct mr_table_ops {
* @mfc_hash: Hash table of all resolved routes for easy lookup
* @mfc_cache_list: list of resovled routes for possible traversal
* @maxvif: Identifier of highest value vif currently in use
- * @cache_resolve_queue_len: current size of unresolved queue
* @mroute_do_assert: Whether to inform userspace on wrong ingress
* @mroute_do_pim: Whether to receive IGMP PIMv1
* @mroute_reg_vif_num: PIM-device vif index
@@ -252,7 +251,6 @@ struct mr_table {
struct rhltable mfc_hash;
struct list_head mfc_cache_list;
int maxvif;
- atomic_t cache_resolve_queue_len;
bool mroute_do_assert;
bool mroute_do_pim;
bool mroute_do_wrvifwhole;
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index c07bc82cbbe9..4d67c64d94a4 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -744,8 +744,6 @@ static void ipmr_destroy_unres(struct mr_table *mrt, struct mfc_cache *c)
struct sk_buff *skb;
struct nlmsgerr *e;
- atomic_dec(&mrt->cache_resolve_queue_len);
-
while ((skb = skb_dequeue(&c->_c.mfc_un.unres.unresolved))) {
if (ip_hdr(skb)->version == 0) {
struct nlmsghdr *nlh = skb_pull(skb,
@@ -1133,9 +1131,11 @@ static int ipmr_cache_unresolved(struct mr_table *mrt, vifi_t vifi,
}
if (!found) {
+ bool was_empty;
+
/* Create a new entry if allowable */
- if (atomic_read(&mrt->cache_resolve_queue_len) >= 10 ||
- (c = ipmr_cache_alloc_unres()) == NULL) {
+ c = ipmr_cache_alloc_unres();
+ if (!c) {
spin_unlock_bh(&mfc_unres_lock);
kfree_skb(skb);
@@ -1161,11 +1161,11 @@ static int ipmr_cache_unresolved(struct mr_table *mrt, vifi_t vifi,
return err;
}
- atomic_inc(&mrt->cache_resolve_queue_len);
+ was_empty = list_empty(&mrt->mfc_unres_queue);
list_add(&c->_c.list, &mrt->mfc_unres_queue);
mroute_netlink_event(mrt, c, RTM_NEWROUTE);
- if (atomic_read(&mrt->cache_resolve_queue_len) == 1)
+ if (was_empty)
mod_timer(&mrt->ipmr_expire_timer,
c->_c.mfc_un.unres.expires);
}
@@ -1272,7 +1272,6 @@ static int ipmr_mfc_add(struct net *net, struct mr_table *mrt,
if (uc->mfc_origin == c->mfc_origin &&
uc->mfc_mcastgrp == c->mfc_mcastgrp) {
list_del(&_uc->list);
- atomic_dec(&mrt->cache_resolve_queue_len);
found = true;
break;
}
@@ -1328,7 +1327,7 @@ static void mroute_clean_tables(struct mr_table *mrt, int flags)
}
if (flags & MRT_FLUSH_MFC) {
- if (atomic_read(&mrt->cache_resolve_queue_len) != 0) {
+ if (!list_empty(&mrt->mfc_unres_queue)) {
spin_lock_bh(&mfc_unres_lock);
list_for_each_entry_safe(c, tmp, &mrt->mfc_unres_queue, list) {
list_del(&c->list);
@@ -2750,9 +2749,22 @@ static int ipmr_rtm_route(struct sk_buff *skb, struct nlmsghdr *nlh,
return ipmr_mfc_delete(tbl, &mfcc, parent);
}
+static int queue_count(struct mr_table *mrt)
+{
+ struct list_head *pos;
+ int count = 0;
+
+ spin_lock_bh(&mfc_unres_lock);
+ list_for_each(pos, &mrt->mfc_unres_queue)
+ count++;
+ spin_unlock_bh(&mfc_unres_lock);
+
+ return count;
+}
+
static bool ipmr_fill_table(struct mr_table *mrt, struct sk_buff *skb)
{
- u32 queue_len = atomic_read(&mrt->cache_resolve_queue_len);
+ u32 queue_len = queue_count(mrt);
if (nla_put_u32(skb, IPMRA_TABLE_ID, mrt->id) ||
nla_put_u32(skb, IPMRA_TABLE_CACHE_RES_QUEUE_LEN, queue_len) ||
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index e80d36c5073d..d02f0f903559 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -768,8 +768,6 @@ static void ip6mr_destroy_unres(struct mr_table *mrt, struct mfc6_cache *c)
struct net *net = read_pnet(&mrt->net);
struct sk_buff *skb;
- atomic_dec(&mrt->cache_resolve_queue_len);
-
while ((skb = skb_dequeue(&c->_c.mfc_un.unres.unresolved)) != NULL) {
if (ipv6_hdr(skb)->version == 0) {
struct nlmsghdr *nlh = skb_pull(skb,
@@ -1148,8 +1146,8 @@ static int ip6mr_cache_unresolved(struct mr_table *mrt, mifi_t mifi,
* Create a new entry if allowable
*/
- if (atomic_read(&mrt->cache_resolve_queue_len) >= 10 ||
- (c = ip6mr_cache_alloc_unres()) == NULL) {
+ c = ip6mr_cache_alloc_unres();
+ if (!c) {
spin_unlock_bh(&mfc_unres_lock);
kfree_skb(skb);
@@ -1176,7 +1174,6 @@ static int ip6mr_cache_unresolved(struct mr_table *mrt, mifi_t mifi,
return err;
}
- atomic_inc(&mrt->cache_resolve_queue_len);
list_add(&c->_c.list, &mrt->mfc_unres_queue);
mr6_netlink_event(mrt, c, RTM_NEWROUTE);
@@ -1468,7 +1465,6 @@ static int ip6mr_mfc_add(struct net *net, struct mr_table *mrt,
if (ipv6_addr_equal(&uc->mf6c_origin, &c->mf6c_origin) &&
ipv6_addr_equal(&uc->mf6c_mcastgrp, &c->mf6c_mcastgrp)) {
list_del(&_uc->list);
- atomic_dec(&mrt->cache_resolve_queue_len);
found = true;
break;
}
@@ -1526,7 +1522,7 @@ static void mroute_clean_tables(struct mr_table *mrt, int flags)
}
if (flags & MRT6_FLUSH_MFC) {
- if (atomic_read(&mrt->cache_resolve_queue_len) != 0) {
+ if (!list_empty(&mrt->mfc_unres_queue)) {
spin_lock_bh(&mfc_unres_lock);
list_for_each_entry_safe(c, tmp, &mrt->mfc_unres_queue, list) {
list_del(&c->list);
--
2.19.2
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