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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,
        Arun Ramadoss <arun.ramadoss@microchip.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        Jakub Kicinski <kuba@kernel.org>
Subject: [PATCH 5.19 214/365] net: dsa: microchip: ksz9477: fix fdb_dump last invalid entry
Date:   Tue, 23 Aug 2022 10:01:55 +0200
Message-Id: <20220823080127.159146679@linuxfoundation.org>
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From: Arun Ramadoss <arun.ramadoss@microchip.com>

commit 36c0d935015766bf20d621c18313f17691bda5e3 upstream.

In the ksz9477_fdb_dump function it reads the ALU control register and
exit from the timeout loop if there is valid entry or search is
complete. After exiting the loop, it reads the alu entry and report to
the user space irrespective of entry is valid. It works till the valid
entry. If the loop exited when search is complete, it reads the alu
table. The table returns all ones and it is reported to user space. So
bridge fdb show gives ff:ff:ff:ff:ff:ff as last entry for every port.
To fix it, after exiting the loop the entry is reported only if it is
valid one.

Fixes: b987e98e50ab ("dsa: add DSA switch driver for Microchip KSZ9477")
Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20220816105516.18350-1-arun.ramadoss@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/dsa/microchip/ksz9477.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/net/dsa/microchip/ksz9477.c
+++ b/drivers/net/dsa/microchip/ksz9477.c
@@ -658,6 +658,9 @@ static int ksz9477_port_fdb_dump(struct
 			goto exit;
 		}
 
+		if (!(ksz_data & ALU_VALID))
+			continue;
+
 		/* read ALU table */
 		ksz9477_read_table(dev, alu_table);