diff mbox series

[RT,2/6] tcp: Remove superfluous BH-disable around listening_hash

Message ID 20201107020727.806739147@goodmis.org
State New
Headers show
Series None | expand

Commit Message

Steven Rostedt Nov. 7, 2020, 2:06 a.m. UTC 
5.4.74-rt42-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

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.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 net/ipv4/inet_hashtables.c  | 19 ++++++++++++-------
 net/ipv6/inet6_hashtables.c |  5 +----
 2 files changed, 13 insertions(+), 11 deletions(-)

Comments

Steven Rostedt Nov. 9, 2020, 5:01 p.m. UTC | #1 
On Mon, 9 Nov 2020 10:22:31 +0100
Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote:

> On 2020-11-06 21:06:38 [-0500], Steven Rostedt wrote:
> > 5.4.74-rt42-rc1 stable review patch.
> > If anyone has any objections, please let me know.  
> 
> Please drop that one. Lockep complains on RT with newer softirq code.
> Older RT and mainline does not complain here unless it observes
> inet_listen_hashbucket::lock in serving-softirq context (which is not
> the case).
> 

Note, I took this because it mentioned:

"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."

And that commit was added in 4.10.

I will remove it and release a rc2.

Thanks!

-- Steve
diff mbox series

Patch

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;
 }