On Mon, 2017-05-22 at 18:09 +0200, Enric Balletbo i Serra wrote:

The IEEE80211_SCAN_RESULT_EXPIRE value was modified several times in
the
past. Initially was set at 10 seconds (2a51931192), then increased at
15
seconds (09f97e0fc4) and finally to 30 seconds (f9616e0f88) to cover
the
use case when a station is having heavy uplink traffic. On some
devices,
like Chromebooks, this value is decreased to 7 seconds to avoid stall
results, and other devices prefer set to 15 seconds.

This simple patch tries to make the selection of this value a bit
more
flexible by being able to set the expire time at config stage. Most
users
can leave the default value set as 30 seconds, others can modify the
value
at config stage if they want lower or bigger values.

I'm not really all that convinced that we really need this - userspace
should just be using the flush thing more often, and then it doesn't
really matter.

However, maybe that doesn't really matter all that much.

But,

+config CFG80211_SCAN_RESULT_EXPIRE
+	int "Scan completion time" if CFG80211

That should have "if CFG80211 && EXPERT" or something like that - no
need to prompt everyone for it.

+	rdev->scan_result_expire =
CONFIG_CFG80211_SCAN_RESULT_EXPIRE;

This is completely pointless - no need to go through runtime like that.

-#define IEEE80211_SCAN_RESULT_EXPIRE	(30 * HZ)

You can just use CONFIG_CFG80211_SCAN_RESULT_EXPIRE * HZ here.

+	__cfg80211_bss_expire(rdev, jiffies - rdev-

quoted

scan_result_expire);

You also completely messed this up because it now depends on HZ.

johannes