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ath9k: fix race conditions when stop device

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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 should fix Ben's kernel crash from:
http://marc.info/?l=linux-wireless&m=129438358921501&w=2

Cc: stable@kernel.org
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Stanislaw Gruszka 2011-01-25 14:08:40 +01:00 • committed by John W. Linville
parent c9234a662e
commit 203043f579
2 changed files with 9 additions and 5 deletions
drivers/net/wireless/ath/ath9k
init.cmain.c

5
drivers/net/wireless/ath/ath9k/init.c
View file

@ -598,8 +598,6 @@ static int ath9k_init_softc(u16 devid, struct ath_softc *sc, u16 subsysid,
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;
}

9
drivers/net/wireless/ath/ath9k/main.c
View file

@ -1309,6 +1309,9 @@ 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);
@ -1326,6 +1329,12 @@ 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;