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> Reinette -- 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
