[PATCH] Revert "wifi: iwlwifi: trans: remove STATUS_SUSPENDED"

[Chris Bainbridge <chris.bainbridge@gmail.com>]

This reverts commit e769f6f27ffe41331e00b69a33aa8a34db4dd830.

The removal of STATUS_SUSPENDED (which tracks suspend/resume state)
resulted in an intermittent race condition on resume. The fault can be
reproduced by carrying out repeated suspend/resume cycles while passing
traffic through the NIC. A typical failure looks like:

[  141.093986] iwlwifi 0000:01:00.0: Error sending SCAN_CFG_CMD: time out after 2000ms.
[  141.094057] iwlwifi 0000:01:00.0: Current CMD queue read_ptr 441 write_ptr 442
[  141.094864] iwlwifi 0000:01:00.0: Start IWL Error Log Dump:
[  141.094866] iwlwifi 0000:01:00.0: Transport status: 0x00000042, valid: 6
[  141.094870] iwlwifi 0000:01:00.0: Loaded firmware version: 89.7f71c7f4.0 ty-a0-gf-a0-89.ucode
[  141.094873] iwlwifi 0000:01:00.0: 0x01000071 | ADVANCED_SYSASSERT
...
[  141.098401] iwlwifi 0000:01:00.0: iwl_mvm_check_rt_status failed, device is gone during suspend

The kernel then oops due to a null pointer dereference in
iwl_mvm_realloc_queues_after_restart().

Fixes: e769f6f27ffe ("wifi: iwlwifi: trans: remove STATUS_SUSPENDED")
Closes: https://yhbt.net/lore/linux-wireless/aTDoDiD55qlUZ0pn@debian.local/
Cc: <stable@vger.kernel.org>
Signed-off-by: Chris Bainbridge <chris.bainbridge@gmail.com>
---
 .../net/wireless/intel/iwlwifi/iwl-trans.c    | 22 +++++++++++++++++--
 .../net/wireless/intel/iwlwifi/iwl-trans.h    |  3 +++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-trans.c b/drivers/net/wireless/intel/iwlwifi/iwl-trans.c
index cc8a84018f70..f5c4aa165c5b 100644
--- a/drivers/net/wireless/intel/iwlwifi/iwl-trans.c
+++ b/drivers/net/wireless/intel/iwlwifi/iwl-trans.c
@@ -306,6 +306,9 @@ int iwl_trans_send_cmd(struct iwl_trans *trans, struct iwl_host_cmd *cmd)
 		     test_bit(STATUS_RFKILL_OPMODE, &trans->status)))
 		return -ERFKILL;
 
+	if (unlikely(test_bit(STATUS_SUSPENDED, &trans->status)))
+		return -EHOSTDOWN;
+
 	if (unlikely(test_bit(STATUS_FW_ERROR, &trans->status)))
 		return -EIO;
 
@@ -406,6 +409,8 @@ int iwl_trans_start_hw(struct iwl_trans *trans)
 	might_sleep();
 
 	clear_bit(STATUS_TRANS_RESET_IN_PROGRESS, &trans->status);
+	/* opmode may not resume if it detects errors */
+	clear_bit(STATUS_SUSPENDED, &trans->status);
 
 	return iwl_trans_pcie_start_hw(trans);
 }
@@ -505,17 +510,30 @@ iwl_trans_dump_data(struct iwl_trans *trans, u32 dump_mask,
 
 int iwl_trans_d3_suspend(struct iwl_trans *trans, bool reset)
 {
+	int err;
+
 	might_sleep();
 
-	return iwl_trans_pcie_d3_suspend(trans, reset);
+	err = iwl_trans_pcie_d3_suspend(trans, reset);
+
+	if (!err)
+		set_bit(STATUS_SUSPENDED, &trans->status);
+
+	return err;
 }
 IWL_EXPORT_SYMBOL(iwl_trans_d3_suspend);
 
 int iwl_trans_d3_resume(struct iwl_trans *trans, bool reset)
 {
+	int err;
+
 	might_sleep();
 
-	return iwl_trans_pcie_d3_resume(trans, reset);
+	err = iwl_trans_pcie_d3_resume(trans, reset);
+
+	clear_bit(STATUS_SUSPENDED, &trans->status);
+
+	return err;
 }
 IWL_EXPORT_SYMBOL(iwl_trans_d3_resume);
 
diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-trans.h b/drivers/net/wireless/intel/iwlwifi/iwl-trans.h
index a552669db6e2..c4d06a323f9b 100644
--- a/drivers/net/wireless/intel/iwlwifi/iwl-trans.h
+++ b/drivers/net/wireless/intel/iwlwifi/iwl-trans.h
@@ -290,6 +290,8 @@ static inline void iwl_free_rxb(struct iwl_rx_cmd_buffer *r)
  *	the firmware state yet
  * @STATUS_TRANS_RESET_IN_PROGRESS: reset is still in progress, don't
  *	attempt another reset yet
+ * @STATUS_SUSPENDED: device is suspended, don't send commands that
+ *	aren't marked accordingly
  */
 enum iwl_trans_status {
 	STATUS_SYNC_HCMD_ACTIVE,
@@ -303,6 +305,7 @@ enum iwl_trans_status {
 	STATUS_IN_SW_RESET,
 	STATUS_RESET_PENDING,
 	STATUS_TRANS_RESET_IN_PROGRESS,
+	STATUS_SUSPENDED,
 };
 
 static inline int
-- 
2.47.3