netdev - [PATH RFC net-next 8/8] net: phy: Add build warning if assumptions get broken

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Date:   Fri, 14 Sep 2018 23:38:56 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     netdev <netdev@...r.kernel.org>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>
Subject: [PATH RFC net-next 8/8] net: phy: Add build warning if assumptions get broken

The macro magic to build constant bitmaps of supported PHY features
breaks when we have more than 63 ETHTOOL_LINK_MODE bits. Make the
breakage loud, not a subtle bug, when we get to that condition.

Signed-off-by: Andrew Lunn <andrew@...n.ch>
---
 drivers/net/phy/phy_device.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index eed61ee1d394..7bee59c7834b 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -2297,6 +2297,13 @@ static int __init phy_init(void)
 {
 	int rc;
 
+	/* The phy_basic_features, phy_gbit_features etc, above, only
+	 * work for values up to 63. Ensure we get a loud error if
+	 * this threshold is exceeded, and the necessary changes are
+	 * made.
+	 */
+	BUILD_BUG_ON(__ETHTOOL_LINK_MODE_LAST > 63);
+
 	rc = mdio_bus_init();
 	if (rc)
 		return rc;
-- 
2.19.0.rc1