[PATCH v3 12/14] net: amt: Remove redundant rcu_read_lock/unlock() in spin_lock

[pengdonglin]

From: pengdonglin <pengdong...@xiaomi.com>

Since commit a8bb74acd8efe ("rcu: Consolidate RCU-sched update-side function 
definitions")
there is no difference between rcu_read_lock(), rcu_read_lock_bh() and
rcu_read_lock_sched() in terms of RCU read section and the relevant grace
period. That means that spin_lock(), which implies rcu_read_lock_sched(),
also implies rcu_read_lock().

There is no need no explicitly start a RCU read section if one has already
been started implicitly by spin_lock().

Simplify the code and remove the inner rcu_read_lock() invocation.

Cc: Taehee Yoo <ap420...@gmail.com>
Cc: Andrew Lunn <andrew+net...@lunn.ch>
Cc: "David S. Miller" <da...@davemloft.net>
Cc: Eric Dumazet <eduma...@google.com>
Cc: Jakub Kicinski <k...@kernel.org>
Signed-off-by: pengdonglin <pengdong...@xiaomi.com>
Signed-off-by: pengdonglin <dolinux.p...@gmail.com>
---
 drivers/net/amt.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/drivers/net/amt.c b/drivers/net/amt.c
index ed86537b2f61..aaed9fbc7526 100644
--- a/drivers/net/amt.c
+++ b/drivers/net/amt.c
@@ -295,7 +295,6 @@ static void amt_source_work(struct work_struct *work)
 
        tunnel = gnode->tunnel_list;
        spin_lock_bh(&tunnel->lock);
-       rcu_read_lock();
        if (gnode->filter_mode == MCAST_INCLUDE) {
                amt_destroy_source(snode);
                if (!gnode->nr_sources)
@@ -306,7 +305,6 @@ static void amt_source_work(struct work_struct *work)
                 */
                snode->status = AMT_SOURCE_STATUS_D_FWD;
        }
-       rcu_read_unlock();
        spin_unlock_bh(&tunnel->lock);
 }
 
@@ -426,7 +424,6 @@ static void amt_group_work(struct work_struct *work)
                goto out;
        }
 
-       rcu_read_lock();
        for (i = 0; i < buckets; i++) {
                hlist_for_each_entry_safe(snode, t,
                                          &gnode->sources[i], node) {
@@ -443,7 +440,6 @@ static void amt_group_work(struct work_struct *work)
                amt_del_group(amt, gnode);
        else
                gnode->filter_mode = MCAST_INCLUDE;
-       rcu_read_unlock();
        spin_unlock_bh(&tunnel->lock);
 out:
        dev_put(amt->dev);
@@ -1327,11 +1323,9 @@ static void amt_clear_groups(struct amt_tunnel_list 
*tunnel)
        int i;
 
        spin_lock_bh(&tunnel->lock);
-       rcu_read_lock();
        for (i = 0; i < amt->hash_buckets; i++)
                hlist_for_each_entry_safe(gnode, t, &tunnel->groups[i], node)
                        amt_del_group(amt, gnode);
-       rcu_read_unlock();
        spin_unlock_bh(&tunnel->lock);
 }
 
@@ -1343,11 +1337,9 @@ static void amt_tunnel_expire(struct work_struct *work)
        struct amt_dev *amt = tunnel->amt;
 
        spin_lock_bh(&amt->lock);
-       rcu_read_lock();
        list_del_rcu(&tunnel->list);
        amt->nr_tunnels--;
        amt_clear_groups(tunnel);
-       rcu_read_unlock();
        spin_unlock_bh(&amt->lock);
        kfree_rcu(tunnel, rcu);
 }
-- 
2.34.1