ath9k: fix race conditions when stop device
RFC 1/1 ath9k: fix race conditions when stop device
We do not kill any scheduled tasklets when stopping device, that may cause usage of resources after free. Moreover we enable interrupts in tasklet function, so we could potentially end with interrupts enabled when driver is not ready to receive them.
I think patch could fix Ben's kernel crash from:
http://marc.info/?l=linux-wireless&m=129438358921501&w=2
RFC for now as I'm not quite familiar with ath9k. If get confirmation patch is correct, I will repost and cc to -stable.
Signed-off-by Stanislaw Gruszka <[email protected]>
--- drivers/net/wireless/ath/ath9k/init.c | 5 ----- drivers/net/wireless/ath/ath9k/main.c | 9 +++++++++ 2 files changed, 9 insertions(+), 5 deletions(-)
drivers/net/wireless/ath/ath9k/init.c +0 -5
@@ -598,8 +598,6 @@ err_btcoex: err_queues:ath9k_hw_deinit (ah); err_hw: -tasklet_kill (&sc->intr_tq); -tasklet_kill (&sc->bcon_tasklet);kfree (ah); sc->sc_ah =NULL ;
@@ -807,9 +805,6 @@ static void ath9k_deinit_softc(struct ath_softc *sc)ath9k_hw_deinit (sc->sc_ah); -tasklet_kill (&sc->intr_tq); -tasklet_kill (&sc->bcon_tasklet); -kfree (sc->sc_ah); sc->sc_ah =NULL ; }
drivers/net/wireless/ath/ath9k/main.c +9 -0
@@ -1320,6 +1320,9 @@ static void ath9k_stop(struct ieee80211_hw *hw)spin_lock_bh (&sc->sc_pcu_lock); +/* prevent tasklets to enable interrupts once we disable them */ + ah->imask &= ~ATH9K_INT_GLOBAL ; +/* make sure h/w will not generate any interrupt * before setting the invalid flag. */ ath9k_hw_disable_interrupts (ah);
@@ -1337,6 +1340,12 @@ static void ath9k_stop(struct ieee80211_hw *hw)spin_unlock_bh (&sc->sc_pcu_lock); +/* we can now sync irq and kill any running tasklets, since we already +* disabled interrupts and not holding a spin lock */ +synchronize_irq (sc->irq); +tasklet_kill (&sc->intr_tq); +tasklet_kill (&sc->bcon_tasklet); +ath9k_ps_restore (sc); sc->ps_idle = true;
Signature · 1 line
1.7.1