[PATCH ath-next v2 2/5] wifi: ath11k: keep the radios when a firmware recovery fails

[Julius Bairaktaris <julius@bairaktaris.de>]

On a firmware crash recovery ath11k_mac_allocate() keeps the registered
radios, but the error paths of ath11k_core_start() and
ath11k_core_qmi_firmware_ready() still call ath11k_mac_destroy(). A
failed recovery thus frees an ieee80211_hw that mac80211 still uses and
leaves ab->pdevs[i].ar NULL. A frame bridged to the radio then follows
the freed hw:

  Unable to handle kernel paging request at virtual address
  ffffff8316cfd480
  pc : sta_info_hash_lookup+0x4c/0xe4 [mac80211]
  Call trace:
   sta_info_hash_lookup+0x4c/0xe4 [mac80211] (P)
   sta_info_get_bss+0x1c/0x78 [mac80211]
   ieee80211_lookup_ra_sta+0x124/0x14c [mac80211]
   __ieee80211_subif_start_xmit+0xb8/0x3a0 [mac80211]
   ieee80211_subif_start_xmit+0x50/0x750 [mac80211]
   dev_hard_start_xmit+0x98/0x120

and driver removal dereferences the NULL ar:

  Unable to handle kernel access to user memory outside uaccess routines
  at virtual address 0000000000000000
  pc : ath11k_dp_rx_pdev_free+0x34/0x12c [ath11k]
  Call trace:
   ath11k_dp_rx_pdev_free+0x34/0x12c [ath11k] (P)
   ath11k_dp_pdev_free+0x4c/0x84 [ath11k]
   ath11k_core_deinit+0xdc/0x168 [ath11k]
   ath11k_ahb_remove+0x30/0x90 [ath11k_ahb]

Destroy the radios only when ATH11K_FLAG_REGISTERED is clear, as
ath11k_mac_allocate() does.

Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.9.0.1-02146-QCAHKSWPL_SILICONZ-1

Fixes: 0366f42640a4 ("ath11k: Move mac80211 hw allocation before wmi_init command")
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Julius Bairaktaris <julius@bairaktaris.de>
---
 drivers/net/wireless/ath/ath11k/core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/core.c b/drivers/net/wireless/ath/ath11k/core.c
index 8e4dab61a3009..dd256853bab57 100644
--- a/drivers/net/wireless/ath/ath11k/core.c
+++ b/drivers/net/wireless/ath/ath11k/core.c
@@ -2231,7 +2231,8 @@ static int ath11k_core_start(struct ath11k_base *ab)
 err_reo_cleanup:
 	ath11k_dp_pdev_reo_cleanup(ab);
 err_mac_destroy:
-	ath11k_mac_destroy(ab);
+	if (!test_bit(ATH11K_FLAG_REGISTERED, &ab->dev_flags))
+		ath11k_mac_destroy(ab);
 err_hif_stop:
 	ath11k_hif_stop(ab);
 err_wmi_detach:
@@ -2315,7 +2316,8 @@ int ath11k_core_qmi_firmware_ready(struct ath11k_base *ab)
 
 err_core_stop:
 	ath11k_core_stop(ab);
-	ath11k_mac_destroy(ab);
+	if (!test_bit(ATH11K_FLAG_REGISTERED, &ab->dev_flags))
+		ath11k_mac_destroy(ab);
 err_dp_free:
 	ath11k_dp_free(ab);
 	mutex_unlock(&ab->core_lock);
-- 
2.53.0