From f115eda8475ee45ef3668a64bb3940056aad894e Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Mon, 12 Oct 2020 17:33:54 +0200
Subject: [PATCH] tcp: Remove superfluous BH-disable around listening_hash
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: f115eda8475ee45ef3668a64bb3940056aad894e
Patch-mainline: Queued in subsystem maintainer repository
References: bsc#1188525

Commit
   9652dc2eb9e40 ("tcp: relax listening_hash operations")

removed the need to disable bottom half while acquiring
listening_hash.lock. There are still two callers left which disable
bottom half before the lock is acquired.

Drop local_bh_disable() around __inet_hash() which acquires
listening_hash->lock, invoke inet_ehash_nolisten() with disabled BH.
inet_unhash() conditionally acquires listening_hash->lock.

Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/linux-rt-users/12d6f9879a97cd56c09fb53dee343cbb14f7f1f7.camel@gmx.de/
Link: https://lkml.kernel.org/r/X9CheYjuXWc75Spa@hirez.programming.kicks-ass.net
Signed-off-by: Varad Gautam <varad.gautam@suse.com>

---
 net/ipv4/inet_hashtables.c  | 19 ++++++++++++-------
 net/ipv6/inet6_hashtables.c |  5 +----
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 006a34b18537..4c8565d6624c 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -543,7 +543,9 @@ int __inet_hash(struct sock *sk, struct sock *osk)
 	int err = 0;
 
 	if (sk->sk_state != TCP_LISTEN) {
+		local_bh_disable();
 		inet_ehash_nolisten(sk, osk);
+		local_bh_enable();
 		return 0;
 	}
 	WARN_ON(!sk_unhashed(sk));
@@ -575,11 +577,8 @@ int inet_hash(struct sock *sk)
 {
 	int err = 0;
 
-	if (sk->sk_state != TCP_CLOSE) {
-		local_bh_disable();
+	if (sk->sk_state != TCP_CLOSE)
 		err = __inet_hash(sk, NULL);
-		local_bh_enable();
-	}
 
 	return err;
 }
@@ -590,17 +589,20 @@ void inet_unhash(struct sock *sk)
 	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 	struct inet_listen_hashbucket *ilb = NULL;
 	spinlock_t *lock;
+	bool state_listen;
 
 	if (sk_unhashed(sk))
 		return;
 
 	if (sk->sk_state == TCP_LISTEN) {
+		state_listen = true;
 		ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
-		lock = &ilb->lock;
+		spin_lock(&ilb->lock);
 	} else {
+		state_listen = false;
 		lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
+		spin_lock_bh(lock);
 	}
-	spin_lock_bh(lock);
 	if (sk_unhashed(sk))
 		goto unlock;
 
@@ -613,7 +615,10 @@ void inet_unhash(struct sock *sk)
 	__sk_nulls_del_node_init_rcu(sk);
 	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
 unlock:
-	spin_unlock_bh(lock);
+	if (state_listen)
+		spin_unlock(&ilb->lock);
+	else
+		spin_unlock_bh(lock);
 }
 EXPORT_SYMBOL_GPL(inet_unhash);
 
diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index fbe9d4295eac..5d1c1c6967cb 100644
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -287,11 +287,8 @@ int inet6_hash(struct sock *sk)
 {
 	int err = 0;
 
-	if (sk->sk_state != TCP_CLOSE) {
-		local_bh_disable();
+	if (sk->sk_state != TCP_CLOSE)
 		err = __inet_hash(sk, NULL);
-		local_bh_enable();
-	}
 
 	return err;
 }
-- 
2.30.2