diff options
| author | Linus Lüssing <ll@simonwunderlich.de> | 2021-10-05 16:55:53 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-11-26 11:40:30 +0100 |
| commit | baf1055650d89eab0ff7483dd0088005e538b6e7 (patch) | |
| tree | bbc6a033a330f1142ffa6295b1ebf4168541d21e | |
| parent | e87453000a35afc65b87d8022262384a24119c41 (diff) | |
ath9k: Fix potential interrupt storm on queue reset
[ Upstream commit 4925642d541278575ad1948c5924d71ffd57ef14 ]
In tests with two Lima boards from 8devices (QCA4531 based) on OpenWrt
19.07 we could force a silent restart of a device with no serial
output when we were sending a high amount of UDP traffic (iperf3 at 80
MBit/s in both directions from external hosts, saturating the wifi and
causing a load of about 4.5 to 6) and were then triggering an
ath9k_queue_reset().
Further debugging showed that the restart was caused by the ath79
watchdog. With disabled watchdog we could observe that the device was
constantly going into ath_isr() interrupt handler and was returning
early after the ATH_OP_HW_RESET flag test, without clearing any
interrupts. Even though ath9k_queue_reset() calls
ath9k_hw_kill_interrupts().
With JTAG we could observe the following race condition:
1) ath9k_queue_reset()
...
-> ath9k_hw_kill_interrupts()
-> set_bit(ATH_OP_HW_RESET, &common->op_flags);
...
<- returns
2) ath9k_tasklet()
...
-> ath9k_hw_resume_interrupts()
...
<- returns
3) loops around:
...
handle_int()
-> ath_isr()
...
-> if (test_bit(ATH_OP_HW_RESET,
&common->op_flags))
return IRQ_HANDLED;
x) ath_reset_internal():
=> never reached <=
And in ath_isr() we would typically see the following interrupts /
interrupt causes:
* status: 0x00111030 or 0x00110030
* async_cause: 2 (AR_INTR_MAC_IPQ)
* sync_cause: 0
So the ath9k_tasklet() reenables the ath9k interrupts
through ath9k_hw_resume_interrupts() which ath9k_queue_reset() had just
disabled. And ath_isr() then keeps firing because it returns IRQ_HANDLED
without actually clearing the interrupt.
To fix this IRQ storm also clear/disable the interrupts again when we
are in reset state.
Cc: Sven Eckelmann <sven@narfation.org>
Cc: Simon Wunderlich <sw@simonwunderlich.de>
Cc: Linus Lüssing <linus.luessing@c0d3.blue>
Fixes: 872b5d814f99 ("ath9k: do not access hardware on IRQs during reset")
Signed-off-by: Linus Lüssing <ll@simonwunderlich.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210914192515.9273-3-linus.luessing@c0d3.blue
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/net/wireless/ath/ath9k/main.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c index 173960682ea0..507d8c514968 100644 --- a/drivers/net/wireless/ath/ath9k/main.c +++ b/drivers/net/wireless/ath/ath9k/main.c @@ -529,8 +529,10 @@ irqreturn_t ath_isr(int irq, void *dev) ath9k_debug_sync_cause(sc, sync_cause); status &= ah->imask; /* discard unasked-for bits */ - if (test_bit(ATH_OP_HW_RESET, &common->op_flags)) + if (test_bit(ATH_OP_HW_RESET, &common->op_flags)) { + ath9k_hw_kill_interrupts(sc->sc_ah); return IRQ_HANDLED; + } /* * If there are no status bits set, then this interrupt was not |