net: hns3: fix the concurrency between functions reading debugfs

commit 9c9a042 upstream.

Currently, the debugfs mechanism is that all functions share a
global variable to save the pointer for obtaining data. When
different functions concurrently access the same file node,
repeated release exceptions occur. Therefore, the granularity
of the pointer for storing the obtained data is adjusted to be
private for each function.

Fixes: 5e69ea7 ("net: hns3: refactor the debugfs process")
Signed-off-by: Yufeng Mo <moyufeng@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/ethernet/hisilicon/hns3/hnae3.h

@@ -844,6 +844,7 @@ struct hnae3_handle {
 	struct dentry *hnae3_dbgfs;
 	/* protects concurrent contention between debugfs commands */
 	struct mutex dbgfs_lock;
+	char **dbgfs_buf;
 
 	/* Network interface message level enabled bits */
 	u32 msg_enable;

drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c

@@ -1227,7 +1227,7 @@ static ssize_t hns3_dbg_read(struct file *filp, char __user *buffer,
 		return ret;
 
 	mutex_lock(&handle->dbgfs_lock);
-	save_buf = &hns3_dbg_cmd[index].buf;
+	save_buf = &handle->dbgfs_buf[index];
 
 	if (!test_bit(HNS3_NIC_STATE_INITED, &priv->state) ||
 	    test_bit(HNS3_NIC_STATE_RESETTING, &priv->state)) {
@@ -1332,6 +1332,13 @@ int hns3_dbg_init(struct hnae3_handle *handle)
 	int ret;
 	u32 i;
 
+	handle->dbgfs_buf = devm_kcalloc(&handle->pdev->dev,
+					 ARRAY_SIZE(hns3_dbg_cmd),
+					 sizeof(*handle->dbgfs_buf),
+					 GFP_KERNEL);
+	if (!handle->dbgfs_buf)
+		return -ENOMEM;
+
 	hns3_dbg_dentry[HNS3_DBG_DENTRY_COMMON].dentry =
 				debugfs_create_dir(name, hns3_dbgfs_root);
 	handle->hnae3_dbgfs = hns3_dbg_dentry[HNS3_DBG_DENTRY_COMMON].dentry;
@@ -1380,9 +1387,9 @@ void hns3_dbg_uninit(struct hnae3_handle *handle)
 	u32 i;
 
 	for (i = 0; i < ARRAY_SIZE(hns3_dbg_cmd); i++)
-		if (hns3_dbg_cmd[i].buf) {
-			kvfree(hns3_dbg_cmd[i].buf);
-			hns3_dbg_cmd[i].buf = NULL;
+		if (handle->dbgfs_buf[i]) {
+			kvfree(handle->dbgfs_buf[i]);
+			handle->dbgfs_buf[i] = NULL;
 		}
 
 	mutex_destroy(&handle->dbgfs_lock);

drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.h

@@ -49,7 +49,6 @@ struct hns3_dbg_cmd_info {
 	enum hnae3_dbg_cmd cmd;
 	enum hns3_dbg_dentry_type dentry;
 	u32 buf_len;
-	char *buf;
 	int (*init)(struct hnae3_handle *handle, unsigned int cmd);
 };