[PATCH ath-next v2 2/2] wifi: ath11k: disable interrupts during firmware crash recovery

[Julius Bairaktaris <julius@bairaktaris.de>]

On IPQ8074 a firmware assert reboots the SoC:

  Unable to handle kernel read from unreadable memory at virtual address 0
  pc : ath11k_hal_srng_access_begin+0xc/0x60 [ath11k]
  lr : ath11k_dp_rx_process_mon_status+0x15c/0xd84 [ath11k]
  Call trace:
   ath11k_hal_srng_access_begin+0xc/0x60 [ath11k]
   ath11k_dp_rx_process_mon_rings+0xa0/0x5d4 [ath11k]
   ath11k_dp_service_srng+0x1f4/0x348 [ath11k]
   ath11k_ahb_ext_grp_napi_poll+0x34/0xd4 [ath11k_ahb]
   __napi_poll+0x38/0x188
   net_rx_action+0x120/0x2c0

ath11k_core_reconfigure_on_crash() tears the data path down with
ath11k_dp_pdev_free(), ath11k_dp_free() and ath11k_hal_srng_clear(),
which memsets the ring list. The DP NAPI is still running while that
happens, so it services a ring whose address pointer has just been
cleared.

That function used to disable the interrupts first, until
commit d455e805de70 ("wifi: ath11k: rearrange IRQ enable/disable in reset path")
moved the disable into ath11k_core_reset(). reset_work is only queued
from mhi.c and from the debugfs hw-restart handler, so AHB parts never
run it on a real firmware crash. Their recovery goes QMI server exit ->
restart_work -> ath11k_core_reconfigure_on_crash() ->
ath11k_core_qmi_firmware_ready(), and nothing disables the interrupts
anywhere along it.

Disable them again on the crash path. The reset path has already done
so by the time it gets here, hence the ab->is_reset check.

This is also why the debugfs hw-restart trigger never showed the
problem: it goes through ath11k_core_reset(), the one path that still
had the disable.

Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.12-01460-QCAHKSWPL_SILICONZ-1

Fixes: d455e805de70 ("wifi: ath11k: rearrange IRQ enable/disable in reset path")
Assisted-by: Claude:claude-opus-5
Signed-off-by: Julius Bairaktaris <julius@bairaktaris.de>
---
 drivers/net/wireless/ath/ath11k/core.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/net/wireless/ath/ath11k/core.c b/drivers/net/wireless/ath/ath11k/core.c
index 8039124e7832..d2ed6a0ea7e3 100644
--- a/drivers/net/wireless/ath/ath11k/core.c
+++ b/drivers/net/wireless/ath/ath11k/core.c
@@ -2334,6 +2334,16 @@ static int ath11k_core_reconfigure_on_crash(struct ath11k_base *ab)
 
 	mutex_lock(&ab->core_lock);
 	ath11k_thermal_unregister(ab);
+
+	/*
+	 * ath11k_core_reset() already disabled the interrupts on the reset
+	 * path; only the firmware crash path reaches here with them live.
+	 */
+	if (!ab->is_reset) {
+		ath11k_hif_irq_disable(ab);
+		ath11k_hif_ce_irq_disable(ab);
+	}
+
 	ath11k_dp_pdev_free(ab);
 	ath11k_cfr_deinit(ab);
 	ath11k_spectral_deinit(ab);
-- 
2.53.0