[PATCH net 2/3] Revert "openvswitch: Use nested-BH locking for ovs_pcpu_storage"

[Gal Pressman <gal@nvidia.com>]

This reverts commit 672318331b44753ab7bd8545558939c38b4c1132.

Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Gal Pressman <gal@nvidia.com>
---
 net/openvswitch/actions.c  | 31 +++++++++++++++++++++++++++++--
 net/openvswitch/datapath.c | 24 ------------------------
 net/openvswitch/datapath.h | 33 ---------------------------------
 3 files changed, 29 insertions(+), 59 deletions(-)

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 435725c27a55..7e4a8d41b9ed 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -39,6 +39,15 @@
 #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;
@@ -55,10 +64,28 @@ struct ovs_frag_data {
 
 static DEFINE_PER_CPU(struct ovs_frag_data, ovs_frag_data_storage);
 
-DEFINE_PER_CPU(struct ovs_pcpu_storage, ovs_pcpu_storage) = {
-	.bh_lock = INIT_LOCAL_LOCK(bh_lock),
+#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;
+};
+
+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.
  */
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 6a304ae2d959..aaa6277bb49c 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -244,13 +244,11 @@ void ovs_dp_detach_port(struct vport *p)
 /* Must be called with rcu_read_lock. */
 void ovs_dp_process_packet(struct sk_buff *skb, struct sw_flow_key *key)
 {
-	struct ovs_pcpu_storage *ovs_pcpu = this_cpu_ptr(&ovs_pcpu_storage);
 	const struct vport *p = OVS_CB(skb)->input_vport;
 	struct datapath *dp = p->dp;
 	struct sw_flow *flow;
 	struct sw_flow_actions *sf_acts;
 	struct dp_stats_percpu *stats;
-	bool ovs_pcpu_locked = false;
 	u64 *stats_counter;
 	u32 n_mask_hit;
 	u32 n_cache_hit;
@@ -292,26 +290,10 @@ void ovs_dp_process_packet(struct sk_buff *skb, struct sw_flow_key *key)
 
 	ovs_flow_stats_update(flow, key->tp.flags, skb);
 	sf_acts = rcu_dereference(flow->sf_acts);
-	/* This path can be invoked recursively: Use the current task to
-	 * identify recursive invocation - the lock must be acquired only once.
-	 * Even with disabled bottom halves this can be preempted on PREEMPT_RT.
-	 * Limit the locking to RT to avoid assigning `owner' if it can be
-	 * avoided.
-	 */
-	if (IS_ENABLED(CONFIG_PREEMPT_RT) && ovs_pcpu->owner != current) {
-		local_lock_nested_bh(&ovs_pcpu_storage.bh_lock);
-		ovs_pcpu->owner = current;
-		ovs_pcpu_locked = true;
-	}
-
 	error = ovs_execute_actions(dp, skb, sf_acts, key);
 	if (unlikely(error))
 		net_dbg_ratelimited("ovs: action execution error on datapath %s: %d\n",
 				    ovs_dp_name(dp), error);
-	if (ovs_pcpu_locked) {
-		ovs_pcpu->owner = NULL;
-		local_unlock_nested_bh(&ovs_pcpu_storage.bh_lock);
-	}
 
 	stats_counter = &stats->n_hit;
 
@@ -689,13 +671,7 @@ static int ovs_packet_cmd_execute(struct sk_buff *skb, struct genl_info *info)
 	sf_acts = rcu_dereference(flow->sf_acts);
 
 	local_bh_disable();
-	local_lock_nested_bh(&ovs_pcpu_storage.bh_lock);
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		this_cpu_write(ovs_pcpu_storage.owner, current);
 	err = ovs_execute_actions(dp, packet, sf_acts, &flow->key);
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		this_cpu_write(ovs_pcpu_storage.owner, NULL);
-	local_unlock_nested_bh(&ovs_pcpu_storage.bh_lock);
 	local_bh_enable();
 	rcu_read_unlock();
 
diff --git a/net/openvswitch/datapath.h b/net/openvswitch/datapath.h
index 4a665c3cfa90..a12640792605 100644
--- a/net/openvswitch/datapath.h
+++ b/net/openvswitch/datapath.h
@@ -173,39 +173,6 @@ struct ovs_net {
 	bool xt_label;
 };
 
-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 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;
-	struct task_struct *owner;
-	local_lock_t bh_lock;
-};
-DECLARE_PER_CPU(struct ovs_pcpu_storage, ovs_pcpu_storage);
-
 /**
  * enum ovs_pkt_hash_types - hash info to include with a packet
  * to send to userspace.
-- 
2.40.1