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authorHangbin Liu <liuhangbin@gmail.com>2019-09-06 10:36:01 +0300
committerDavid S. Miller <davem@davemloft.net>2019-09-07 18:49:00 +0300
commit0079ad8e8dc3a4d1af0dd4a53345580a6947beba (patch)
tree2b109bf325c4c90497be693745a647c91aca0b5a /net/ipv4/ipmr.c
parent06be463368774067d100b237145d9d75db9e05af (diff)
downloadlinux-0079ad8e8dc3a4d1af0dd4a53345580a6947beba.tar.xz
ipmr: remove hard code cache_resolve_queue_len limit
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 limit 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 limit 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 v3: instead of remove cache_resolve_queue_len totally, let's only remove the hard code limit when allocate the unresolved cache, as Eric Dumazet suggested, so we don't need to re-count it in other places. v2: hold the mfc_unres_lock while walking the unresolved list in queue_count(), as Nikolay Aleksandrov remind. Reported-by: Phil Karn <karn@ka9q.net> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com> Reviewed-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ipmr.c')
-rw-r--r--net/ipv4/ipmr.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index c07bc82cbbe9..313470f6bb14 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -1134,8 +1134,8 @@ static int ipmr_cache_unresolved(struct mr_table *mrt, vifi_t vifi,
if (!found) {
/* 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);