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From:   Horatiu Vultur <horatiu.vultur@microchip.com>
To:     <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
CC:     <UNGLinuxDriver@microchip.com>, <davem@davemloft.net>,
        <edumazet@google.com>, <kuba@kernel.org>, <pabeni@redhat.com>,
        <vladimir.oltean@nxp.com>,
        Horatiu Vultur <horatiu.vultur@microchip.com>
Subject: [PATCH net 3/5] net: lan966x: Fix usage of lan966x->mac_lock when entry is removed
Date:   Thu, 14 Jul 2022 21:40:38 +0200
Message-ID: <20220714194040.231651-4-horatiu.vultur@microchip.com>
In-Reply-To: <20220714194040.231651-1-horatiu.vultur@microchip.com>
References: <20220714194040.231651-1-horatiu.vultur@microchip.com>
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To remove an entry to the MAC table, it is required first to setup the
entry and then issue a command for the MAC to forget the entry.
So if it happens for two threads to remove simultaneously an entry
in MAC table then it would be a race condition.
Fix this by using lan966x->mac_lock to protect the HW access.

Fixes: e18aba8941b40 ("net: lan966x: add mactable support")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
---
 .../ethernet/microchip/lan966x/lan966x_mac.c  | 24 +++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_mac.c b/drivers/net/ethernet/microchip/lan966x/lan966x_mac.c
index 4f8fd5cde950..d0b8eba0a66d 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_mac.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_mac.c
@@ -119,11 +119,13 @@ int lan966x_mac_learn(struct lan966x *lan966x, int port,
 	return __lan966x_mac_learn(lan966x, port, false, mac, vid, type);
 }
 
-int lan966x_mac_forget(struct lan966x *lan966x,
-		       const unsigned char mac[ETH_ALEN],
-		       unsigned int vid,
-		       enum macaccess_entry_type type)
+static int lan966x_mac_forget_locked(struct lan966x *lan966x,
+				     const unsigned char mac[ETH_ALEN],
+				     unsigned int vid,
+				     enum macaccess_entry_type type)
 {
+	lockdep_assert_held(&lan966x->mac_lock);
+
 	lan966x_mac_select(lan966x, mac, vid);
 
 	/* Issue a forget command */
@@ -134,6 +136,20 @@ int lan966x_mac_forget(struct lan966x *lan966x,
 	return lan966x_mac_wait_for_completion(lan966x);
 }
 
+int lan966x_mac_forget(struct lan966x *lan966x,
+		       const unsigned char mac[ETH_ALEN],
+		       unsigned int vid,
+		       enum macaccess_entry_type type)
+{
+	int ret;
+
+	spin_lock(&lan966x->mac_lock);
+	ret = lan966x_mac_forget_locked(lan966x, mac, vid, type);
+	spin_unlock(&lan966x->mac_lock);
+
+	return ret;
+}
+
 int lan966x_mac_cpu_learn(struct lan966x *lan966x, const char *addr, u16 vid)
 {
 	return lan966x_mac_learn(lan966x, PGID_CPU, addr, vid, ENTRYTYPE_LOCKED);
-- 
2.33.0