drop_monitor: Split tracing enable / disable to different functions

Subsequent patches will need to enable / disable tracing based on the
configured alerting mode.

Reduce the nesting level and prepare for the introduction of this
functionality by splitting the tracing enable / disable operations into
two different functions.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index 4deb86f..8b9b0b8 100644 (file)
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -241,11 +241,58 @@ static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi,
        rcu_read_unlock();
 }
 
+static int net_dm_trace_on_set(struct netlink_ext_ack *extack)
+{
+       int rc;
+
+       if (!try_module_get(THIS_MODULE)) {
+               NL_SET_ERR_MSG_MOD(extack, "Failed to take reference on module");
+               return -ENODEV;
+       }
+
+       rc = register_trace_kfree_skb(trace_kfree_skb_hit, NULL);
+       if (rc) {
+               NL_SET_ERR_MSG_MOD(extack, "Failed to connect probe to kfree_skb() tracepoint");
+               goto err_module_put;
+       }
+
+       rc = register_trace_napi_poll(trace_napi_poll_hit, NULL);
+       if (rc) {
+               NL_SET_ERR_MSG_MOD(extack, "Failed to connect probe to napi_poll() tracepoint");
+               goto err_unregister_trace;
+       }
+
+       return 0;
+
+err_unregister_trace:
+       unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
+err_module_put:
+       module_put(THIS_MODULE);
+       return rc;
+}
+
+static void net_dm_trace_off_set(void)
+{
+       struct dm_hw_stat_delta *new_stat, *temp;
+
+       unregister_trace_napi_poll(trace_napi_poll_hit, NULL);
+       unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
+
+       tracepoint_synchronize_unregister();
+
+       list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) {
+               if (new_stat->dev == NULL) {
+                       list_del_rcu(&new_stat->list);
+                       kfree_rcu(new_stat, rcu);
+               }
+       }
+
+       module_put(THIS_MODULE);
+}
+
 static int set_all_monitor_traces(int state, struct netlink_ext_ack *extack)
 {
        int rc = 0;
-       struct dm_hw_stat_delta *new_stat = NULL;
-       struct dm_hw_stat_delta *temp;
 
        if (state == trace_state) {
                NL_SET_ERR_MSG_MOD(extack, "Trace state already set to requested state");
@@ -254,34 +301,10 @@ static int set_all_monitor_traces(int state, struct netlink_ext_ack *extack)
 
        switch (state) {
        case TRACE_ON:
-               if (!try_module_get(THIS_MODULE)) {
-                       NL_SET_ERR_MSG_MOD(extack, "Failed to take reference on module");
-                       rc = -ENODEV;
-                       break;
-               }
-
-               rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL);
-               rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL);
+               rc = net_dm_trace_on_set(extack);
                break;
-
        case TRACE_OFF:
-               rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
-               rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL);
-
-               tracepoint_synchronize_unregister();
-
-               /*
-                * Clean the device list
-                */
-               list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) {
-                       if (new_stat->dev == NULL) {
-                               list_del_rcu(&new_stat->list);
-                               kfree_rcu(new_stat, rcu);
-                       }
-               }
-
-               module_put(THIS_MODULE);
-
+               net_dm_trace_off_set();
                break;
        default:
                rc = 1;