diff mbox series

[RESEND,V2,net,3/7] net: hns3: Resolved the issue that the debugfs query result is inconsistent.

Message ID 20241217010839.1742227-4-shaojijie@huawei.com (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series There are some bugfix for the HNS3 ethernet driver | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 8 of 10 maintainers
netdev/build_clang success Errors and warnings before: 130 this patch: 130
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 154 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-12-17--03-00 (tests: 795)

Commit Message

Jijie Shao Dec. 17, 2024, 1:08 a.m. UTC 
From: Hao Lan <lanhao@huawei.com>

This patch modifies the implementation of debugfs:

When the user process stops unexpectedly, not all data of the file system
is read. In this case, the save_buf pointer is not released. When the
user process is called next time, save_buf is used to copy the cached
data to the user space. As a result, the queried data is stale.

To solve this problem, this patch implements .open() and .release() handler
for debugfs file_operations. moving allocation buffer and execution
of the cmd to the .open() handler and freeing in to the .release() handler.
Allocate separate buffer for each reader and associate the buffer
with the file pointer.
When different user read processes no longer share the buffer,
the stale data problem is fixed.

Fixes: 5e69ea7ee2a6 ("net: hns3: refactor the debugfs process")
Signed-off-by: Hao Lan <lanhao@huawei.com>
Signed-off-by: Guangwei Zhang <zhangwangwei6@huawei.com>
Signed-off-by: Jijie Shao <shaojijie@huawei.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
ChangeLog:
v1 -> v2:
  - Fix a data inconsistency issue caused by simultaneous access of multiple readers,
    suggested by Jakub.
  v1: https://lore.kernel.org/all/20241107133023.3813095-1-shaojijie@huawei.com/
---
 drivers/net/ethernet/hisilicon/hns3/hnae3.h   |  3 -
 .../ethernet/hisilicon/hns3/hns3_debugfs.c    | 96 ++++++-------------
 2 files changed, 31 insertions(+), 68 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/hisilicon/hns3/hnae3.h b/drivers/net/ethernet/hisilicon/hns3/hnae3.h
index 710a8f9f2248..12ba380eb701 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hnae3.h
+++ b/drivers/net/ethernet/hisilicon/hns3/hnae3.h
@@ -916,9 +916,6 @@  struct hnae3_handle {
 
 	u8 netdev_flags;
 	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;
diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c b/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c
index 807eb3bbb11c..9bbece25552b 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c
@@ -1260,69 +1260,55 @@  static int hns3_dbg_read_cmd(struct hns3_dbg_data *dbg_data,
 static ssize_t hns3_dbg_read(struct file *filp, char __user *buffer,
 			     size_t count, loff_t *ppos)
 {
-	struct hns3_dbg_data *dbg_data = filp->private_data;
+	char *buf = filp->private_data;
+
+	return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
+}
+
+static int hns3_dbg_open(struct inode *inode, struct file *filp)
+{
+	struct hns3_dbg_data *dbg_data = inode->i_private;
 	struct hnae3_handle *handle = dbg_data->handle;
 	struct hns3_nic_priv *priv = handle->priv;
-	ssize_t size = 0;
-	char **save_buf;
-	char *read_buf;
 	u32 index;
+	char *buf;
 	int ret;
 
+	if (!test_bit(HNS3_NIC_STATE_INITED, &priv->state) ||
+	    test_bit(HNS3_NIC_STATE_RESETTING, &priv->state))
+		return -EBUSY;
+
 	ret = hns3_dbg_get_cmd_index(dbg_data, &index);
 	if (ret)
 		return ret;
 
-	mutex_lock(&handle->dbgfs_lock);
-	save_buf = &handle->dbgfs_buf[index];
-
-	if (!test_bit(HNS3_NIC_STATE_INITED, &priv->state) ||
-	    test_bit(HNS3_NIC_STATE_RESETTING, &priv->state)) {
-		ret = -EBUSY;
-		goto out;
-	}
-
-	if (*save_buf) {
-		read_buf = *save_buf;
-	} else {
-		read_buf = kvzalloc(hns3_dbg_cmd[index].buf_len, GFP_KERNEL);
-		if (!read_buf) {
-			ret = -ENOMEM;
-			goto out;
-		}
-
-		/* save the buffer addr until the last read operation */
-		*save_buf = read_buf;
-
-		/* get data ready for the first time to read */
-		ret = hns3_dbg_read_cmd(dbg_data, hns3_dbg_cmd[index].cmd,
-					read_buf, hns3_dbg_cmd[index].buf_len);
-		if (ret)
-			goto out;
-	}
+	buf = kvzalloc(hns3_dbg_cmd[index].buf_len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	size = simple_read_from_buffer(buffer, count, ppos, read_buf,
-				       strlen(read_buf));
-	if (size > 0) {
-		mutex_unlock(&handle->dbgfs_lock);
-		return size;
+	ret = hns3_dbg_read_cmd(dbg_data, hns3_dbg_cmd[index].cmd,
+				buf, hns3_dbg_cmd[index].buf_len);
+	if (ret) {
+		kvfree(buf);
+		return ret;
 	}
 
-out:
-	/* free the buffer for the last read operation */
-	if (*save_buf) {
-		kvfree(*save_buf);
-		*save_buf = NULL;
-	}
+	filp->private_data = buf;
+	return 0;
+}
 
-	mutex_unlock(&handle->dbgfs_lock);
-	return ret;
+static int hns3_dbg_release(struct inode *inode, struct file *filp)
+{
+	kvfree(filp->private_data);
+	filp->private_data = NULL;
+	return 0;
 }
 
 static const struct file_operations hns3_dbg_fops = {
 	.owner = THIS_MODULE,
-	.open  = simple_open,
+	.open  = hns3_dbg_open,
 	.read  = hns3_dbg_read,
+	.release = hns3_dbg_release,
 };
 
 static int hns3_dbg_bd_file_init(struct hnae3_handle *handle, u32 cmd)
@@ -1379,13 +1365,6 @@  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;
@@ -1395,8 +1374,6 @@  int hns3_dbg_init(struct hnae3_handle *handle)
 			debugfs_create_dir(hns3_dbg_dentry[i].name,
 					   handle->hnae3_dbgfs);
 
-	mutex_init(&handle->dbgfs_lock);
-
 	for (i = 0; i < ARRAY_SIZE(hns3_dbg_cmd); i++) {
 		if ((hns3_dbg_cmd[i].cmd == HNAE3_DBG_CMD_TM_NODES &&
 		     ae_dev->dev_version <= HNAE3_DEVICE_VERSION_V2) ||
@@ -1425,24 +1402,13 @@  int hns3_dbg_init(struct hnae3_handle *handle)
 out:
 	debugfs_remove_recursive(handle->hnae3_dbgfs);
 	handle->hnae3_dbgfs = NULL;
-	mutex_destroy(&handle->dbgfs_lock);
 	return ret;
 }
 
 void hns3_dbg_uninit(struct hnae3_handle *handle)
 {
-	u32 i;
-
 	debugfs_remove_recursive(handle->hnae3_dbgfs);
 	handle->hnae3_dbgfs = NULL;
-
-	for (i = 0; i < ARRAY_SIZE(hns3_dbg_cmd); i++)
-		if (handle->dbgfs_buf[i]) {
-			kvfree(handle->dbgfs_buf[i]);
-			handle->dbgfs_buf[i] = NULL;
-		}
-
-	mutex_destroy(&handle->dbgfs_lock);
 }
 
 void hns3_dbg_register_debugfs(const char *debugfs_dir_name)