openvswitch: Use nested-BH locking for ovs_pcpu_storage

ovs_pcpu_storage is a per-CPU variable and relies on disabled BH for its
locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT
this data structure requires explicit locking.
The data structure can be referenced recursive and there is a recursion
counter to avoid too many recursions.

Add a local_lock_t to the data structure and use
local_lock_nested_bh() for locking. Add an owner of the struct which is
the current task and acquire the lock only if the structure is not owned
by the current task.

Cc: Aaron Conole <aconole@redhat.com>
Cc: Eelco Chaudron <echaudro@redhat.com>
Cc: Ilya Maximets <i.maximets@ovn.org>
Cc: dev@openvswitch.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Link: https://patch.msgid.link/20250512092736.229935-9-bigeasy@linutronix.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 2 insertions, 29 deletions

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 7e4a8d41b9ed..435725c27a55 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -39,15 +39,6 @@
 #include "flow_netlink.h"
 #include "openvswitch_trace.h"
 
-struct deferred_action {
-	struct sk_buff *skb;
-	const struct nlattr *actions;
-	int actions_len;
-
-	/* Store pkt_key clone when creating deferred action. */
-	struct sw_flow_key pkt_key;
-};
-
 #define MAX_L2_LEN	(VLAN_ETH_HLEN + 3 * MPLS_HLEN)
 struct ovs_frag_data {
 	unsigned long dst;
@@ -64,28 +55,10 @@ struct ovs_frag_data {
 
 static DEFINE_PER_CPU(struct ovs_frag_data, ovs_frag_data_storage);
 
-#define DEFERRED_ACTION_FIFO_SIZE 10
-#define OVS_RECURSION_LIMIT 5
-#define OVS_DEFERRED_ACTION_THRESHOLD (OVS_RECURSION_LIMIT - 2)
-struct action_fifo {
-	int head;
-	int tail;
-	/* Deferred action fifo queue storage. */
-	struct deferred_action fifo[DEFERRED_ACTION_FIFO_SIZE];
-};
-
-struct action_flow_keys {
-	struct sw_flow_key key[OVS_DEFERRED_ACTION_THRESHOLD];
-};
-
-struct ovs_pcpu_storage {
-	struct action_fifo action_fifos;
-	struct action_flow_keys flow_keys;
-	int exec_level;
+DEFINE_PER_CPU(struct ovs_pcpu_storage, ovs_pcpu_storage) = {
+	.bh_lock = INIT_LOCAL_LOCK(bh_lock),
 };
 
-static DEFINE_PER_CPU(struct ovs_pcpu_storage, ovs_pcpu_storage);
-
 /* Make a clone of the 'key', using the pre-allocated percpu 'flow_keys'
  * space. Return NULL if out of key spaces.
  */