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commit cf15d6b63ade66b2b811866d71a0bfe901d312ee
Author: Fotis Panagiotopoulos <f.pa...@amco.gr>
AuthorDate: Mon Feb 13 16:57:17 2023 +0200
Improvements in Netlink connections allocation.
---
net/netlink/Kconfig | 41 ++++++++++++++++++++++++++++++++++++++---
net/netlink/netlink_conn.c | 43 +++++++++++++++++++++++++++++++++----------
2 files changed, 71 insertions(+), 13 deletions(-)
diff --git a/net/netlink/Kconfig b/net/netlink/Kconfig
index d92efeff03..0a07a04364 100644
--- a/net/netlink/Kconfig
+++ b/net/netlink/Kconfig
@@ -22,11 +22,46 @@ config NET_NETLINK
if NET_NETLINK
-config NETLINK_CONNS
- int "Number of Netlink connections"
+config NETLINK_PREALLOC_CONNS
+ int "Preallocated Netlink connections"
default 4
---help---
- Maximum number of Netlink connections (all tasks).
+ Number of Netlink connections (all tasks).
+
+ This number of connections will be pre-allocated during system
boot.
+ If dynamic connections allocation is enabled, more connections
may
+ be allocated at a later time, as the system needs them. Else
this
+ will be the maximum number of connections available to the
system
+ at all times.
+
+ Set to 0 to disable (and rely only on dynamic allocations).
+
+config NETLINK_ALLOC_CONNS
+ int "Dynamic Netlink connections allocation"
+ default 0
+ ---help---
+ Dynamic memory allocations for Netlink.
+
+ When set to 0 all dynamic allocations are disabled.
+
+ When set to 1 a new connection will be allocated every time,
+ and it will be free'd when no longer needed.
+
+ Setting this to 2 or more will allocate the connections in
+ batches (with batch size equal to this config). When a
+ connection is no longer needed, it will be returned to the
+ free connections pool, and it will never be deallocated!
+
+config NETLINK_MAX_CONNS
+ int "Maximum number of Netlink connections"
+ default 0
+ depends on NETLINK_ALLOC_CONNS > 0
+ ---help---
+ If dynamic connections allocation is selected
(NETLINK_ALLOC_CONNS > 0)
+ this will limit the number of connections that can be allocated.
+
+ This is useful in case the system is under very heavy load (or
+ under attack), ensuring that the heap will not be exhausted.
menu "Netlink Protocols"
diff --git a/net/netlink/netlink_conn.c b/net/netlink/netlink_conn.c
index 772b733eb9..443e004b0b 100644
--- a/net/netlink/netlink_conn.c
+++ b/net/netlink/netlink_conn.c
@@ -51,8 +51,9 @@
/* The array containing all NetLink connections. */
-#ifndef CONFIG_NET_ALLOC_CONNS
-static struct netlink_conn_s g_netlink_connections[CONFIG_NETLINK_CONNS];
+#if CONFIG_NETLINK_PREALLOC_CONNS > 0
+static struct netlink_conn_s
+ g_netlink_connections[CONFIG_NETLINK_PREALLOC_CONNS];
#endif
/* A list of all free NetLink connections */
@@ -106,10 +107,10 @@ static void netlink_response_available(FAR void *arg)
void netlink_initialize(void)
{
-#ifndef CONFIG_NET_ALLOC_CONNS
+#if CONFIG_NETLINK_PREALLOC_CONNS > 0
int i;
- for (i = 0; i < CONFIG_NETLINK_CONNS; i++)
+ for (i = 0; i < CONFIG_NETLINK_PREALLOC_CONNS; i++)
{
/* Mark the connection closed and move it to the free list */
@@ -131,20 +132,29 @@ void netlink_initialize(void)
FAR struct netlink_conn_s *netlink_alloc(void)
{
FAR struct netlink_conn_s *conn;
-#ifdef CONFIG_NET_ALLOC_CONNS
+#if CONFIG_NETLINK_ALLOC_CONNS > 0
int i;
#endif
/* The free list is protected by a mutex. */
nxmutex_lock(&g_free_lock);
-#ifdef CONFIG_NET_ALLOC_CONNS
+#if CONFIG_NETLINK_ALLOC_CONNS > 0
if (dq_peek(&g_free_netlink_connections) == NULL)
{
- conn = kmm_zalloc(sizeof(*conn) * CONFIG_NETLINK_CONNS);
+#if CONFIG_NETLINK_MAX_CONNS > 0
+ if (dq_count(&g_active_netlink_connections) +
+ CONFIG_NETLINK_ALLOC_CONNS >= CONFIG_NETLINK_MAX_CONNS)
+ {
+ nxmutex_unlock(&g_free_lock);
+ return NULL;
+ }
+#endif
+
+ conn = kmm_zalloc(sizeof(*conn) * CONFIG_NETLINK_ALLOC_CONNS);
if (conn != NULL)
{
- for (i = 0; i < CONFIG_NETLINK_CONNS; i++)
+ for (i = 0; i < CONFIG_NETLINK_ALLOC_CONNS; i++)
{
dq_addlast(&conn[i].sconn.node, &g_free_netlink_connections);
}
@@ -199,9 +209,22 @@ void netlink_free(FAR struct netlink_conn_s *conn)
memset(conn, 0, sizeof(*conn));
- /* Free the connection */
+ /* If this is a preallocated or a batch allocated connection store it in
+ * the free connections list. Else free it.
+ */
+
+#if CONFIG_NETLINK_ALLOC_CONNS == 1
+ if (conn < g_netlink_connections || conn >= (g_netlink_connections +
+ CONFIG_NETLINK_PREALLOC_CONNS))
+ {
+ kmm_free(conn);
+ }
+ else
+#endif
+ {
+ dq_addlast(&conn->sconn.node, &g_free_netlink_connections);
+ }
- dq_addlast(&conn->sconn.node, &g_free_netlink_connections);
nxmutex_unlock(&g_free_lock);
}
