hostapd: increase netlink buffer size

When lots of events are waiting to be received, the default buffer size
is not enough, and hostapd can run into "No buffer space available" on
recvmsg. This will cause the netdev state tracking to go out of sync.

Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/package/network/services/hostapd/patches/070-netlink-increase-buffer-size.patch b/package/network/services/hostapd/patches/070-netlink-increase-buffer-size.patch
new file mode 100644 (file)
index 0000000..3f1952f
--- /dev/null
+++ b/package/network/services/hostapd/patches/070-netlink-increase-buffer-size.patch
@@ -0,0 +1,31 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 18 Oct 2025 21:55:44 +0200
+Subject: [PATCH] netlink: increase buffer size
+
+When lots of events are waiting to be received, the default buffer size
+is not enough, and hostapd can run into "No buffer space available" on
+recvmsg. This will cause the netdev state tracking to go out of sync.
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/src/drivers/netlink.c
++++ b/src/drivers/netlink.c
+@@ -92,6 +92,7 @@ struct netlink_data * netlink_init(struc
+ {
+       struct netlink_data *netlink;
+       struct sockaddr_nl local;
++      int size = 262144;
+ 
+       netlink = os_zalloc(sizeof(*netlink));
+       if (netlink == NULL)
+@@ -105,6 +106,9 @@ struct netlink_data * netlink_init(struc
+               return NULL;
+       }
+ 
++      setsockopt(netlink->sock, SOL_SOCKET, SO_RCVBUF, &size, sizeof(size));
++      setsockopt(netlink->sock, SOL_SOCKET, SO_SNDBUF, &size, sizeof(size));
++
+       os_memset(&local, 0, sizeof(local));
+       local.nl_family = AF_NETLINK;
+       local.nl_groups = RTMGRP_LINK;