[PATCH -next 0/3] cleanup of devtmpfs_*_node()

[PATCH -next 0/3] cleanup of devtmpfs_*_node()

[Longlong Xia]

In one test, when modprobe zram, no zram device was found in the /dev. 
But don't see any errors printed in jouranls/dmesg. Later we found out 
that the reason was that device_add() did not check its return value when
calling devtmpfs_create_node(). So we hope to turn devtmpfs_*_node() & 
devtmpfs_submit_req() into a function with no return value, and add some
debug info in the handle() that actually processes the request to let the
user know why the creation was not successful.

Patch [1] devtmpfs: convert to pr_fmt. 
Patch [2] devtmpfs: add debug info to handle().
Patch [3] devtmpfs: Remove return value of devtmpfs_*_node() & 
devtmpfs_submit_req().

Longlong Xia (3):
  devtmpfs: convert to pr_fmt
  devtmpfs: add debug info to handle()
  devtmpfs: remove return value of devtmpfs_*_node() &
    devtmpfs_submit_req()

 drivers/base/base.h     |  8 +++----
 drivers/base/devtmpfs.c | 48 +++++++++++++++++++++++------------------
 2 files changed, 31 insertions(+), 25 deletions(-)

-- 
2.25.1

[PATCH -next 1/3] devtmpfs: convert to pr_fmt

[Longlong Xia]

Use the pr_fmt() macro to prefix all the output with "devtmpfs: ".
while at it, convert printk(<LEVEL>) to pr_<level>().

Signed-off-by: Longlong Xia <xialonglong1@huawei.com>
---
 drivers/base/devtmpfs.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 03e8a95f1f35..ae72d4ba8547 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -13,6 +13,8 @@
  * overwrite the default setting if needed.
  */
 
+#define pr_fmt(fmt) "devtmpfs: " fmt
+
 #include <linux/kernel.h>
 #include <linux/syscalls.h>
 #include <linux/mount.h>
@@ -376,9 +378,9 @@ int __init devtmpfs_mount(void)
 
 	err = init_mount("devtmpfs", "dev", "devtmpfs", DEVTMPFS_MFLAGS, NULL);
 	if (err)
-		printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
+		pr_info("error mounting %d\n", err);
 	else
-		printk(KERN_INFO "devtmpfs: mounted\n");
+		pr_info("mounted\n");
 	return err;
 }
 
@@ -460,14 +462,12 @@ int __init devtmpfs_init(void)
 
 	mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
 	if (IS_ERR(mnt)) {
-		printk(KERN_ERR "devtmpfs: unable to create devtmpfs %ld\n",
-				PTR_ERR(mnt));
+		pr_err("unable to create devtmpfs %ld\n", PTR_ERR(mnt));
 		return PTR_ERR(mnt);
 	}
 	err = register_filesystem(&dev_fs_type);
 	if (err) {
-		printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
-		       "type %i\n", err);
+		pr_err("unable to register devtmpfs type %d\n", err);
 		return err;
 	}
 
@@ -480,12 +480,12 @@ int __init devtmpfs_init(void)
 	}
 
 	if (err) {
-		printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
+		pr_err("unable to create devtmpfs %d\n", err);
 		unregister_filesystem(&dev_fs_type);
 		thread = NULL;
 		return err;
 	}
 
-	printk(KERN_INFO "devtmpfs: initialized\n");
+	pr_info("initialized\n");
 	return 0;
 }
-- 
2.25.1

[PATCH -next 2/3] devtmpfs: add debug info to handle()

[Longlong Xia]

The devtmpfs_*_node() are used to mount/unmount devices to /dev, but their
callers don't check their return value, so we don't know the reason for
the failure. Let's add some debug info in handle() to help users know
why failed.

Signed-off-by: Longlong Xia <xialonglong1@huawei.com>
---
 drivers/base/devtmpfs.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index ae72d4ba8547..77ca64f708ce 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -389,10 +389,18 @@ static __initdata DECLARE_COMPLETION(setup_done);
 static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
 		  struct device *dev)
 {
+	int ret;
+
 	if (mode)
-		return handle_create(name, mode, uid, gid, dev);
+		ret = handle_create(name, mode, uid, gid, dev);
 	else
-		return handle_remove(name, dev);
+		ret = handle_remove(name, dev);
+
+	if (ret)
+		pr_err_ratelimited("failed to %s %s, ret = %d\n",
+				   mode ? "create" : "remove", name, ret);
+
+	return ret;
 }
 
 static void __noreturn devtmpfs_work_loop(void)
-- 
2.25.1

[PATCH -next 3/3] devtmpfs: remove return value of devtmpfs_*_node() & devtmpfs_submit_req()

[Longlong Xia]

Because the return value of devtmpfs_*_node() and devtmpfs_submit_req()
are not used by their callers, change them into void functions.

Signed-off-by: Longlong Xia <xialonglong1@huawei.com>
---
 drivers/base/base.h     |  8 ++++----
 drivers/base/devtmpfs.c | 20 +++++++++-----------
 2 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/drivers/base/base.h b/drivers/base/base.h
index 2208af509ce8..ffb7321e39cf 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -198,11 +198,11 @@ extern void fw_devlink_drivers_done(void);
 void device_pm_move_to_tail(struct device *dev);
 
 #ifdef CONFIG_DEVTMPFS
-int devtmpfs_create_node(struct device *dev);
-int devtmpfs_delete_node(struct device *dev);
+void devtmpfs_create_node(struct device *dev);
+void devtmpfs_delete_node(struct device *dev);
 #else
-static inline int devtmpfs_create_node(struct device *dev) { return 0; }
-static inline int devtmpfs_delete_node(struct device *dev) { return 0; }
+static inline void devtmpfs_create_node(struct device *dev) { }
+static inline void devtmpfs_delete_node(struct device *dev) { }
 #endif
 
 void software_node_notify(struct device *dev);
diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 77ca64f708ce..3c4e61c99b77 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -103,7 +103,7 @@ static inline int is_blockdev(struct device *dev)
 static inline int is_blockdev(struct device *dev) { return 0; }
 #endif
 
-static int devtmpfs_submit_req(struct req *req, const char *tmp)
+static void devtmpfs_submit_req(struct req *req, const char *tmp)
 {
 	init_completion(&req->done);
 
@@ -116,24 +116,22 @@ static int devtmpfs_submit_req(struct req *req, const char *tmp)
 	wait_for_completion(&req->done);
 
 	kfree(tmp);
-
-	return req->err;
 }
 
-int devtmpfs_create_node(struct device *dev)
+void devtmpfs_create_node(struct device *dev)
 {
 	const char *tmp = NULL;
 	struct req req;
 
 	if (!thread)
-		return 0;
+		return;
 
 	req.mode = 0;
 	req.uid = GLOBAL_ROOT_UID;
 	req.gid = GLOBAL_ROOT_GID;
 	req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
 	if (!req.name)
-		return -ENOMEM;
+		return;
 
 	if (req.mode == 0)
 		req.mode = 0600;
@@ -144,25 +142,25 @@ int devtmpfs_create_node(struct device *dev)
 
 	req.dev = dev;
 
-	return devtmpfs_submit_req(&req, tmp);
+	devtmpfs_submit_req(&req, tmp);
 }
 
-int devtmpfs_delete_node(struct device *dev)
+void devtmpfs_delete_node(struct device *dev)
 {
 	const char *tmp = NULL;
 	struct req req;
 
 	if (!thread)
-		return 0;
+		return;
 
 	req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
 	if (!req.name)
-		return -ENOMEM;
+		return;
 
 	req.mode = 0;
 	req.dev = dev;
 
-	return devtmpfs_submit_req(&req, tmp);
+	devtmpfs_submit_req(&req, tmp);
 }
 
 static int dev_mkdir(const char *name, umode_t mode)
-- 
2.25.1

Re:[PATCH -next] cleanup of devtmpfs_*_node()

[Longlong Xia]

Forget to CC mail list, will resend, please ignore
this one.