package/kernel/mac80211/patches/329-ath9k-fix-race-condition-in-irq-processing-during-ha.patch

   1 From: Felix Fietkau <nbd@openwrt.org>
   2 Date: Wed, 14 Jan 2015 14:13:15 +0100
   3 Subject: [PATCH] ath9k: fix race condition in irq processing during hardware
   4  reset
   5
   6 To fix invalid hardware accesses, the commit
   7 "ath9k: do not access hardware on IRQs during reset" made the irq
   8 handler ignore interrupts emitted after queueing a hardware reset (which
   9 disables the IRQ). This left a small time window for the IRQ to get
  10 re-enabled by the tasklet, which caused IRQ storms.
  11 Instead of returning IRQ_NONE when ATH_OP_HW_RESET is set, disable the
  12 IRQ entirely for the duration of the reset.
  13
  14 Signed-off-by: Felix Fietkau <nbd@openwrt.org>
  15 ---
  16
  17 --- a/drivers/net/wireless/ath/ath9k/main.c
  18 +++ b/drivers/net/wireless/ath/ath9k/main.c
  19 @@ -285,6 +285,7 @@ static int ath_reset_internal(struct ath
  20
  21         __ath_cancel_work(sc);
  22
  23 +       disable_irq(sc->irq);
  24         tasklet_disable(&sc->intr_tq);
  25         tasklet_disable(&sc->bcon_tasklet);
  26         spin_lock_bh(&sc->sc_pcu_lock);
  27 @@ -331,6 +332,7 @@ static int ath_reset_internal(struct ath
  28                 r = -EIO;
  29
  30  out:
  31 +       enable_irq(sc->irq);
  32         spin_unlock_bh(&sc->sc_pcu_lock);
  33         tasklet_enable(&sc->bcon_tasklet);
  34         tasklet_enable(&sc->intr_tq);
  35 @@ -512,9 +514,6 @@ irqreturn_t ath_isr(int irq, void *dev)
  36         if (!ah || test_bit(ATH_OP_INVALID, &common->op_flags))
  37                 return IRQ_NONE;
  38
  39 -       if (!AR_SREV_9100(ah) && test_bit(ATH_OP_HW_RESET, &common->op_flags))
  40 -               return IRQ_NONE;
  41 -
  42         /* shared irq, not for us */
  43         if (!ath9k_hw_intrpend(ah))
  44                 return IRQ_NONE;
  45 @@ -529,7 +528,7 @@ irqreturn_t ath_isr(int irq, void *dev)
  46         ath9k_debug_sync_cause(sc, sync_cause);
  47         status &= ah->imask;    /* discard unasked-for bits */
  48
  49 -       if (AR_SREV_9100(ah) && test_bit(ATH_OP_HW_RESET, &common->op_flags))
  50 +       if (test_bit(ATH_OP_HW_RESET, &common->op_flags))
  51                 return IRQ_HANDLED;
  52
  53         /*