[PATCH 0/1] iwlwifi: trace debug messages

Luis Henriques luis.henriques at canonical.com
Mon Sep 3 12:52:44 UTC 2012

BugLink: http://bugs.launchpad.net/bugs/1035889

== Precise SRU Justification ==

This bug prevents users using the iwlwifi driver to change wireless card
rates, as the system just freezes a while after changing the rate.

For example, running the command:

iwconfig wlan0 rate 11M

will freeze the system.

== Fix ==

It looks like the issue is due to an overflow of debug messages to the
kernel logs.  After bisecting the kernel, commit:

2655e314c4b204966008689eaf3e87ba1f38d55c iwlwifi: trace debug messages

does fix the problem.  This commit had to be backported to the Precise
kernel as it didn't applied cleanly.  The original bug reporter claims
the issue is fixed with this backport.

== Impact ==

It is possible that this fix will not only solve the problem reported in
bug #1035889, but also other problems related with performance
degradation using this driver (but this has not been tested).

== Test Case ==

On a system using the iwlwifi driver, just executed:

 iwconfig wlan0 rate 11M

And after a few seconds the system will stop responding.

Johannes Berg (1):
  iwlwifi: trace debug messages

 drivers/net/wireless/iwlwifi/Makefile       |    2 +-
 drivers/net/wireless/iwlwifi/iwl-debug.c    |  127 +++++++++++++++++++++++++++
 drivers/net/wireless/iwlwifi/iwl-debug.h    |   65 +++++++++-----
 drivers/net/wireless/iwlwifi/iwl-devtrace.h |   65 ++++++++++++++
 4 files changed, 236 insertions(+), 23 deletions(-)
 create mode 100644 drivers/net/wireless/iwlwifi/iwl-debug.c


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