From: Paulo Alcantara <pc@cjr.nz>
Date: Tue, 13 Sep 2022 21:34:51 -0700
Subject: [PATCH] cifs: add missing spinlock around tcon refcount
Git-commit: 621a41ae0834cec9cab312d600d2b9de41dc6eac
References: bsc#1190317
Patch-mainline: v6.0-rc6

Add missing spinlock to protect updates on tcon refcount in
cifs_put_tcon().

Fixes: d7d7a66aacd6 ("cifs: avoid use of global locks for high contention data")
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Enzo Matsumiya <ematsumiya@suse.de>
---
 fs/cifs/connect.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3582,7 +3582,9 @@ cifs_put_tcon(struct cifs_tcon *tcon)
 	ses = tcon->ses;
 	cifs_dbg(FYI, "%s: tc_count=%d\n", __func__, tcon->tc_count);
 	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&tcon->tc_lock);
 	if (--tcon->tc_count > 0) {
+		spin_unlock(&tcon->tc_lock);
 		spin_unlock(&cifs_tcp_ses_lock);
 		return;
 	}
@@ -3591,6 +3593,7 @@ cifs_put_tcon(struct cifs_tcon *tcon)
 	WARN_ON(tcon->tc_count < 0);
 
 	list_del_init(&tcon->tcon_list);
+	spin_unlock(&tcon->tc_lock);
 	spin_unlock(&cifs_tcp_ses_lock);
 
 	xid = get_xid();