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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Yufeng Mo <moyufeng@huawei.com>,
        Guangbin Huang <huangguangbin2@huawei.com>,
        Paolo Abeni <pabeni@redhat.com>
Subject: [PATCH 5.15 840/913] net: hns3: fix the concurrency between functions reading debugfs
Date:   Tue,  5 Apr 2022 09:31:42 +0200
Message-Id: <20220405070405.008748302@linuxfoundation.org>
In-Reply-To: <20220405070339.801210740@linuxfoundation.org>
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From: Yufeng Mo <moyufeng@huawei.com>

commit 9c9a04212fa380d2e7d1412bb281309955c0a781 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: 5e69ea7ee2a6 ("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        |    1 +
 drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c |   15 +++++++++++----
 drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.h |    1 -
 3 files changed, 12 insertions(+), 5 deletions(-)

--- a/drivers/net/ethernet/hisilicon/hns3/hnae3.h
+++ b/drivers/net/ethernet/hisilicon/hns3/hnae3.h
@@ -835,6 +835,7 @@ 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;
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c
@@ -1022,7 +1022,7 @@ static ssize_t hns3_dbg_read(struct file
 		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)) {
@@ -1127,6 +1127,13 @@ int hns3_dbg_init(struct hnae3_handle *h
 	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;
@@ -1175,9 +1182,9 @@ void hns3_dbg_uninit(struct hnae3_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);
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.h
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.h
@@ -47,7 +47,6 @@ 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);
 };