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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Marcin Wojtas <mw@semihalf.com>,
        Russell King <linux@armlinux.org.uk>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        stable <stable@kernel.org>
Subject: [PATCH 5.15 005/121] net: mvpp2: debugfs: fix memory leak when using debugfs_lookup()
Date:   Tue, 13 Sep 2022 16:03:16 +0200
Message-Id: <20220913140357.557975060@linuxfoundation.org>
In-Reply-To: <20220913140357.323297659@linuxfoundation.org>
References: <20220913140357.323297659@linuxfoundation.org>
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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit fe2c9c61f668cde28dac2b188028c5299cedcc1e upstream.

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time.  Fix this up to be much
simpler logic and only create the root debugfs directory once when the
driver is first accessed.  That resolves the memory leak and makes
things more obvious as to what the intent is.

Cc: Marcin Wojtas <mw@semihalf.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org
Cc: stable <stable@kernel.org>
Fixes: 21da57a23125 ("net: mvpp2: add a debugfs interface for the Header Parser")
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_debugfs.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_debugfs.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_debugfs.c
@@ -700,10 +700,10 @@ void mvpp2_dbgfs_cleanup(struct mvpp2 *p
 
 void mvpp2_dbgfs_init(struct mvpp2 *priv, const char *name)
 {
-	struct dentry *mvpp2_dir, *mvpp2_root;
+	static struct dentry *mvpp2_root;
+	struct dentry *mvpp2_dir;
 	int ret, i;
 
-	mvpp2_root = debugfs_lookup(MVPP2_DRIVER_NAME, NULL);
 	if (!mvpp2_root)
 		mvpp2_root = debugfs_create_dir(MVPP2_DRIVER_NAME, NULL);