ath10k: Detect conf_mutex held ath10k_drain_tx() calls

ath10k_drain_tx() must not be called with conf_mutex held as workers can
use that also. Add call to lockdep_assert_not_held() on conf_mutex to
detect if conf_mutex is held by the caller.

The idea for this patch stemmed from coming across the comment block
above the ath10k_drain_tx() while reviewing the conf_mutex holds during
to debug the conf_mutex lock assert in ath10k_debug_fw_stats_request().

Adding detection to assert on conf_mutex hold will help detect incorrect
usages that could lead to locking problems when async worker routines try
to call this routine.

Signed-off-by: Shuah Khan <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Kalle Valo <[email protected]>
Link: https://lore.kernel.org/linux-wireless/[email protected]/

Author: shuahkh

drivers/net/wireless/ath/ath10k/mac.c

@@ -4727,6 +4727,8 @@ static void ath10k_mac_op_wake_tx_queue(struct ieee80211_hw *hw,
 /* Must not be called with conf_mutex held as workers can use that also. */
 void ath10k_drain_tx(struct ath10k *ar)
 {
+	lockdep_assert_not_held(&ar->conf_mutex);
+
 	/* make sure rcu-protected mac80211 tx path itself is drained */
 	synchronize_net();