[PATCH] ath10k: Check tx_stats before use it

[Yingying Tang <yintang@codeaurora.org>]

tx_stats will be freed and set to NULL before debugfs_sta node is
removed in station disconnetion process. So if read the debugfs_sta
node there may be NULL pointer error. Add check for tx_stats before
use it to resove this issue.

Signed-off-by: Yingying Tang <yintang@codeaurora.org>
---
 drivers/net/wireless/ath/ath10k/debugfs_sta.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/wireless/ath/ath10k/debugfs_sta.c b/drivers/net/wireless/ath/ath10k/debugfs_sta.c
index 0f3fd65..4a8d94d 100644
--- a/drivers/net/wireless/ath/ath10k/debugfs_sta.c
+++ b/drivers/net/wireless/ath/ath10k/debugfs_sta.c
@@ -674,6 +674,13 @@ static ssize_t ath10k_dbg_sta_dump_tx_stats(struct file *file,
 
 	mutex_lock(&ar->conf_mutex);
 
+	if (!arsta->tx_stats) {
+		ath10k_warn(ar, "failed to get tx stats");
+		mutex_unlock(&ar->conf_mutex);
+		kfree(buf);
+		return 0;
+	}
+
 	spin_lock_bh(&ar->data_lock);
 	for (k = 0; k < ATH10K_STATS_TYPE_MAX; k++) {
 		for (j = 0; j < ATH10K_COUNTER_TYPE_MAX; j++) {
-- 
1.9.1