[ 019/117] cfg80211: warn if db.txt is empty withCONFIG_CFG80211_INTERNAL_REGDB

[Ben Hutchings]

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxxxxx>

commit 80007efeff0568375b08faf93c7aad65602cb97e upstream.

It has happened twice now where elaborate troubleshooting has
undergone on systems where CONFIG_CFG80211_INTERNAL_REGDB [0]
has been set but yet net/wireless/db.txt was not updated.

Despite the documentation on this it seems system integrators could
use some more help with this, so throw out a kernel warning at boot time
when their database is empty.

This does mean that the error-prone system integrator won't likely
realize the issue until they boot the machine but -- it does not seem
to make sense to enable a build bug breaking random build testing.

[0] http://wireless.kernel.org/en/developers/Regulatory/CRDA#CONFIG_CFG80211_INTERNAL_REGDB

Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Cc: Youngsin Lee <youngsin@xxxxxxxxxxxx>
Cc: Raja Mani <rmani@xxxxxxxxxxxxxxxx>
Cc: Senthil Kumar Balasubramanian <senthilb@xxxxxxxxxxxxxxxx>
Cc: Vipin Mehta <vipimeht@xxxxxxxxxxxxxxxx>
Cc: yahuan@xxxxxxxxxxxxxxxx
Cc: jjan@xxxxxxxxxxxxxxxx
Cc: vthiagar@xxxxxxxxxxxxxxxx
Cc: henrykim@xxxxxxxxxxxx
Cc: jouni@xxxxxxxxxxxxxxxx
Cc: athiruve@xxxxxxxxxxxxxxxx
Cc: cjkim@xxxxxxxxxxxx
Cc: philipk@xxxxxxxxxxxxxxxx
Cc: sunnykim@xxxxxxxxxxxx
Cc: sskwak@xxxxxxxxxxxx
Cc: kkim@xxxxxxxxxxxx
Cc: mattbyun@xxxxxxxxxxxx
Cc: ryanlee@xxxxxxxxxxxx
Cc: simbap@xxxxxxxxxxxx
Cc: krislee@xxxxxxxxxxxx
Cc: conner@xxxxxxxxxxxx
Cc: hojinkim@xxxxxxxxxxxx
Cc: honglee@xxxxxxxxxxxx
Cc: johnwkim@xxxxxxxxxxxx
Cc: jinyong@xxxxxxxxxxxxxxxx
Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/wireless/reg.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index e9a0ac8..15f3474 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -388,7 +388,15 @@ static void reg_regdb_query(const char *alpha2)
 
 	schedule_work(&reg_regdb_work);
 }
+
+/* Feel free to add any other sanity checks here */
+static void reg_regdb_size_check(void)
+{
+	/* We should ideally BUILD_BUG_ON() but then random builds would fail */
+	WARN_ONCE(!reg_regdb_size, "db.txt is empty, you should update it...");
+}
 #else
+static inline void reg_regdb_size_check(void) {}
 static inline void reg_regdb_query(const char *alpha2) {}
 #endif /* CONFIG_CFG80211_INTERNAL_REGDB */
 
@@ -2322,6 +2330,8 @@ int __init regulatory_init(void)
 	spin_lock_init(&reg_requests_lock);
 	spin_lock_init(&reg_pending_beacons_lock);
 
+	reg_regdb_size_check();
+
 	cfg80211_regdomain = cfg80211_world_regdom;
 
 	user_alpha2[0] = '9';


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