netdev - [PATCH net-next] net: core: Assert the size of netdev_featres

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Date:   Fri, 27 Apr 2018 13:11:14 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, edumazet@...gle.com,
        Florian Fainelli <f.fainelli@...il.com>
Subject: [PATCH net-next] net: core: Assert the size of netdev_featres_t

We have about 53 netdev_features_t bits defined and counting, add a
build time check to catch when an u64 type will not be enough and we
will have to convert that to a bitmap. This is done in
register_netdevice() for convenience.

Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
 include/linux/netdevice.h | 6 ++++++
 net/core/dev.c            | 1 +
 2 files changed, 7 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 366c32891158..4326bc6b27d1 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -4121,6 +4121,12 @@ const char *netdev_drivername(const struct net_device *dev);
 
 void linkwatch_run_queue(void);
 
+static inline void netdev_features_size_check(void)
+{
+	BUILD_BUG_ON(sizeof(netdev_features_t) * BITS_PER_BYTE <
+		     NETDEV_FEATURE_COUNT);
+}
+
 static inline netdev_features_t netdev_intersect_features(netdev_features_t f1,
 							  netdev_features_t f2)
 {
diff --git a/net/core/dev.c b/net/core/dev.c
index 0a2d46424069..23e6c1aa78c6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7881,6 +7881,7 @@ int register_netdevice(struct net_device *dev)
 	int ret;
 	struct net *net = dev_net(dev);
 
+	netdev_features_size_check();
 	BUG_ON(dev_boot_phase);
 	ASSERT_RTNL();
 
-- 
2.14.1