Don't give up scanning so easily

[Michael Terry]

Binary package hint: wpasupplicant

I was working on a machine with a broadcom wifi card. It used the proprietary wl.o driver. I noticed that when I resumed from suspend or pressed the F2 button (which on this machine is an rfkill button) to enable wifi, reconnection times with NetworkManager were around 30s. This seemed too long to me.

Investigation revealed that wpasupplicant was scanning after the card was brought up in these scenarios, but failed because (I assume) the wl.o driver was not ready yet. Then it gave up scanning. NM never saw new access points, so didn't bother trying to connect. Then it waited 20s, like it does, before asking wpasupplicant to try scanning again. This scan succeeded and NM proceeded to connect.

I came up with the following patch to get wpasupplicant to try a little harder to scan and forwarded it upstream (see linked bug):

Index: wpasupplicant-0.6.9/wpa_supplicant/events.c
===================================================================
--- wpasupplicant-0.6.9.orig/wpa_supplicant/events.c 2010-09-13 15:28:08.000000000 -0400
+++ wpasupplicant-0.6.9/wpa_supplicant/events.c 2010-09-13 15:28:14.000000000 -0400
@@ -619,6 +619,7 @@
   wpa_printf(MSG_DEBUG, "Failed to get scan results - try "
       "scanning again");
   timeout = 1;
+ wpa_s->scan_req = 1; /* Force scan again */
   goto req_scan;
  }

This is a tracking bug for the issue.

[Kalle Valo (kvalo)]

I sent a patch for 0.7 branch to the list:

http://lists.shmoo.com/pipermail/hostap/2010-October/021809.html

[Kalle Valo (kvalo)]

I sent a v3 of the patch upstream:

http://lists.shmoo.com/pipermail/hostap/2011-February/022564.html

I'll try to create a distro patch for natty soon. Quite a few people seem to suffer from this.

[Kalle Valo (kvalo)]

Created branch lp:~kvalo/wpasupplicant/bug-638303 which contains my v3 patch backported 0.7 series and uploaded test packages to my ppa.

amd64:
https://launchpad.net/~kvalo/+archive/ppa/+buildjob/2268538

i386:
https://launchpad.net/~kvalo/+archive/ppa/+buildjob/2268539

[Kalle Valo (kvalo)]

v4 of patch sent:

http://lists.shmoo.com/pipermail/hostap/2011-March/022891.html

[Gema Gomez (gema)]

We would like to get this change integrated.

[Brian Murray (brian-murray)]

Looking closely at v4 of the patch which is linked to in comment #4 it doesn't look like it would apply to the current version of wpasupplicant in Oneiric.

[Pau Oliva (poliva)]

I have adapted the v4 patch above to the current version of wpasupplicant (0.7.3):

https://bugs.launchpad.net/ubuntu/+source/wpasupplicant/+bug/994739/comments/13

Please consider integrating this, as the wl driver is being used in a wide variety of hardware.