[PATCH v2] ath10k: Fix crash during rmmod when probe firmware fails

[Mohammed Shafi Shajakhan]

From: Mohammed Shafi Shajakhan <mohammed at qti.qualcomm.com>

This fixes the below crash when ath10k probe firmware fails,
NAPI polling tries to access a rx ring resource which was never
allocated, fix this by disabling NAPI right away once the probe
firmware fails by calling 'ath10k_hif_stop'. Its good to note
that the error is never propogated to 'ath10k_pci_probe' when
ath10k_core_register fails, so calling 'ath10k_hif_stop' to cleanup
PCI related things seems to be ok

BUG: unable to handle kernel NULL pointer dereference at (null)
IP:  __ath10k_htt_rx_ring_fill_n+0x19/0x230 [ath10k_core]
__ath10k_htt_rx_ring_fill_n+0x19/0x230 [ath10k_core]

Call Trace:

[<ffffffffa113ec62>] ath10k_htt_rx_msdu_buff_replenish+0x42/0x90
[ath10k_core]
[<ffffffffa113f393>] ath10k_htt_txrx_compl_task+0x433/0x17d0
[ath10k_core]
[<ffffffff8114406d>] ? __wake_up_common+0x4d/0x80
[<ffffffff811349ec>] ? cpu_load_update+0xdc/0x150
[<ffffffffa119301d>] ? ath10k_pci_read32+0xd/0x10 [ath10k_pci]
[<ffffffffa1195b17>] ath10k_pci_napi_poll+0x47/0x110 [ath10k_pci]
[<ffffffff817863af>] net_rx_action+0x20f/0x370

Reported-by: Ben Greear <greearb at candelatech.com>
Fixes: 3c97f5de1f28 ("ath10k: implement NAPI support")

Signed-off-by: Mohammed Shafi Shajakhan <mohammed at qti.qualcomm.com>
---
 drivers/net/wireless/ath/ath10k/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/wireless/ath/ath10k/core.c b/drivers/net/wireless/ath/ath10k/core.c
index f7ea4de..15bccc9 100644
--- a/drivers/net/wireless/ath/ath10k/core.c
+++ b/drivers/net/wireless/ath/ath10k/core.c
@@ -2164,6 +2164,7 @@ static int ath10k_core_probe_fw(struct ath10k *ar)
 	ath10k_core_free_firmware_files(ar);
 
 err_power_down:
+	ath10k_hif_stop(ar);
 	ath10k_hif_power_down(ar);
 
 	return ret;
-- 
1.9.1