On Thu, Aug 13, 2009 at 10:12:06AM -0700, reinette chatre wrote: > On Thu, 2009-08-13 at 05:29 -0700, Stanislaw Gruszka wrote: > > Due to rfkill and iwlwifi mishmash of SW / HW killswitch representation, > > we have race conditions which make unable turn wifi radio on, after enable > > and disable again killswitch. I can observe this problem on my laptop > > with iwl3945 device. > > > > In rfkill core HW switch and SW switch are separate 'states'. Device can > > be only in one of 3 states: RFKILL_STATE_SOFT_BLOCKED, RFKILL_STATE_UNBLOCKED, > > RFKILL_STATE_HARD_BLOCKED. Whereas in iwlwifi driver we have separate bits > > STATUS_RF_KILL_HW and STATUS_RF_KILL_SW for HW and SW switches - radio can be > > turned on, only if both bits are cleared. > > > > In this particular race conditions, radio can not be turned on if in driver > > STATUS_RF_KILL_SW bit is set, and rfkill core is in state > > RFKILL_STATE_HARD_BLOCKED, because rfkill core is unable to call > > rfkill->toggle_radio(). This situation can be entered in case: > > > > - killswitch is turned on > > - rfkill core 'see' button change first and move to RFKILL_STATE_SOFT_BLOCKED > > also call ->toggle_radio() and STATE_RF_KILL_SW in driver is set > > - iwl3945 get info about button from hardware to set STATUS_RF_KILL_HW bit and > > force rfkill to move to RFKILL_STATE_HARD_BLOCKED > > - killsiwtch is turend off > > - driver clear STATUS_RF_KILL_HW > > - rfkill core is unable to clear STATUS_RF_KILL_SW in driver > > > > Additionally call to rfkill_epo() when STATUS_RF_KILL_HW in driver is set > > cause move to the same situation. > > > > In 2.6.31 this problem is fixed due to _total_ rewrite of rfkill subsystem. > > This is a quite small fix for 2.6.30.x in iwlwifi driver. We are changing > > internal rfkill state to always have below relations true: > > > > STATUS_RF_KILL_HW=1 STATUS_RF_KILL_SW=1 <-> RFKILL_STATUS_SOFT_BLOCKED > > STATUS_RF_KILL_HW=0 STATUS_RF_KILL_SW=1 <-> RFKILL_STATUS_SOFT_BLOCKED > > STATUS_RF_KILL_HW=1 STATUS_RF_KILL_SW=0 <-> RFKILL_STATUS_HARD_BLOCKED > > STATUS_RF_KILL_HW=0 STATUS_RF_KILL_SW=0 <-> RFKILL_STATUS_UNBLOCKED > > > > Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx> > > --- > > Patch was tested by me only with iwl3945 device. > > Fortunately I have not encountered these race conditions on my system. > Even so, I tested this on a 5100 system and it behaves as expected wrt > rfkill. > > Acked-by: Reinette Chatre <reinette.chatre@xxxxxxxxx> ACK for stable -- John W. Linville Someday the world will need a hero, and you linville@xxxxxxxxxxxxx might be all we have. Be ready. -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
