[PATCH 1/2] debugfs: provide pr_fmt() macro

[PATCH 1/2] debugfs: provide pr_fmt() macro

[Greg Kroah-Hartman]

Use a common "debugfs: " prefix for all pr_* calls in a single place.

Cc: Mark Brown <broonie@kernel.org>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/debugfs/inode.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index acef14ad53db..f04c8475d9a1 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -9,6 +9,8 @@
  *  See ./Documentation/core-api/kernel-api.rst for more details.
  */
 
+#define pr_fmt(fmt)	"debugfs: " fmt
+
 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/mount.h>
@@ -285,7 +287,7 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
 	struct dentry *dentry;
 	int error;
 
-	pr_debug("debugfs: creating file '%s'\n",name);
+	pr_debug("creating file '%s'\n", name);
 
 	if (IS_ERR(parent))
 		return parent;
-- 
2.22.0

[PATCH 2/2] debugfs: log errors when something goes wrong

[Greg Kroah-Hartman]

As it is not recommended that debugfs calls be checked, it was pointed
out that major errors should still be logged somewhere so that
developers and users have a chance to figure out what went wrong.  To
help with this, error logging has been added to the debugfs core so that
it is not needed to be present in every individual file that calls
debugfs.

Reported-by: Mark Brown <broonie@kernel.org>
Reported-by: Takashi Iwai <tiwai@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/debugfs/inode.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index f04c8475d9a1..7f43c8acfcbf 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -2,8 +2,9 @@
 /*
  *  inode.c - part of debugfs, a tiny little debug file system
  *
- *  Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
+ *  Copyright (C) 2004,2019 Greg Kroah-Hartman <greg@kroah.com>
  *  Copyright (C) 2004 IBM Inc.
+ *  Copyright (C) 2019 Linux Foundation <gregkh@linuxfoundation.org>
  *
  *  debugfs is for people to use instead of /proc or /sys.
  *  See ./Documentation/core-api/kernel-api.rst for more details.
@@ -294,8 +295,10 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
 
 	error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
 			      &debugfs_mount_count);
-	if (error)
+	if (error) {
+		pr_err("Unable to pin filesystem for file '%s'\n", name);
 		return ERR_PTR(error);
+	}
 
 	/* If the parent is not specified, we create it in the root.
 	 * We need the root dentry to do this, which is in the super
@@ -309,6 +312,7 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
 	dentry = lookup_one_len(name, parent, strlen(name));
 	if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
 		dput(dentry);
+		pr_err("File '%s' already present!\n", name);
 		dentry = ERR_PTR(-EEXIST);
 	}
 
@@ -351,8 +355,11 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
 		return dentry;
 
 	inode = debugfs_get_inode(dentry->d_sb);
-	if (unlikely(!inode))
+	if (unlikely(!inode)) {
+		pr_err("out of free dentries, can not create file '%s'\n",
+		       name);
 		return failed_creating(dentry);
+	}
 
 	inode->i_mode = mode;
 	inode->i_private = data;
@@ -513,8 +520,11 @@ struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
 		return dentry;
 
 	inode = debugfs_get_inode(dentry->d_sb);
-	if (unlikely(!inode))
+	if (unlikely(!inode)) {
+		pr_err("out of free dentries, can not create directory '%s'\n",
+		       name);
 		return failed_creating(dentry);
+	}
 
 	inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
 	inode->i_op = &simple_dir_inode_operations;
@@ -552,8 +562,11 @@ struct dentry *debugfs_create_automount(const char *name,
 		return dentry;
 
 	inode = debugfs_get_inode(dentry->d_sb);
-	if (unlikely(!inode))
+	if (unlikely(!inode)) {
+		pr_err("out of free dentries, can not create automount '%s'\n",
+		       name);
 		return failed_creating(dentry);
+	}
 
 	make_empty_dir_inode(inode);
 	inode->i_flags |= S_AUTOMOUNT;
@@ -608,6 +621,8 @@ struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
 
 	inode = debugfs_get_inode(dentry->d_sb);
 	if (unlikely(!inode)) {
+		pr_err("out of free dentries, can not create symlink '%s'\n",
+		       name);
 		kfree(link);
 		return failed_creating(dentry);
 	}
-- 
2.22.0

Re: [PATCH 2/2] debugfs: log errors when something goes wrong

[Rafael J. Wysocki]

On Wed, Jul 3, 2019 at 9:17 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> As it is not recommended that debugfs calls be checked, it was pointed
> out that major errors should still be logged somewhere so that
> developers and users have a chance to figure out what went wrong.  To
> help with this, error logging has been added to the debugfs core so that
> it is not needed to be present in every individual file that calls
> debugfs.
>
> Reported-by: Mark Brown <broonie@kernel.org>
> Reported-by: Takashi Iwai <tiwai@suse.de>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Generally speaking

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
>  fs/debugfs/inode.c | 25 ++++++++++++++++++++-----
>  1 file changed, 20 insertions(+), 5 deletions(-)
>
> diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
> index f04c8475d9a1..7f43c8acfcbf 100644
> --- a/fs/debugfs/inode.c
> +++ b/fs/debugfs/inode.c
> @@ -2,8 +2,9 @@
>  /*
>   *  inode.c - part of debugfs, a tiny little debug file system
>   *
> - *  Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
> + *  Copyright (C) 2004,2019 Greg Kroah-Hartman <greg@kroah.com>
>   *  Copyright (C) 2004 IBM Inc.
> + *  Copyright (C) 2019 Linux Foundation <gregkh@linuxfoundation.org>
>   *
>   *  debugfs is for people to use instead of /proc or /sys.
>   *  See ./Documentation/core-api/kernel-api.rst for more details.
> @@ -294,8 +295,10 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
>
>         error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
>                               &debugfs_mount_count);
> -       if (error)
> +       if (error) {
> +               pr_err("Unable to pin filesystem for file '%s'\n", name);

But I'm not sure about the log level here.  Particularly, why would
pr_info() not work?

>                 return ERR_PTR(error);
> +       }
>
>         /* If the parent is not specified, we create it in the root.
>          * We need the root dentry to do this, which is in the super
> @@ -309,6 +312,7 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
>         dentry = lookup_one_len(name, parent, strlen(name));
>         if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
>                 dput(dentry);
> +               pr_err("File '%s' already present!\n", name);
>                 dentry = ERR_PTR(-EEXIST);
>         }
>
> @@ -351,8 +355,11 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
>                 return dentry;
>
>         inode = debugfs_get_inode(dentry->d_sb);
> -       if (unlikely(!inode))
> +       if (unlikely(!inode)) {
> +               pr_err("out of free dentries, can not create file '%s'\n",
> +                      name);
>                 return failed_creating(dentry);
> +       }
>
>         inode->i_mode = mode;
>         inode->i_private = data;
> @@ -513,8 +520,11 @@ struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
>                 return dentry;
>
>         inode = debugfs_get_inode(dentry->d_sb);
> -       if (unlikely(!inode))
> +       if (unlikely(!inode)) {
> +               pr_err("out of free dentries, can not create directory '%s'\n",
> +                      name);
>                 return failed_creating(dentry);
> +       }
>
>         inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
>         inode->i_op = &simple_dir_inode_operations;
> @@ -552,8 +562,11 @@ struct dentry *debugfs_create_automount(const char *name,
>                 return dentry;
>
>         inode = debugfs_get_inode(dentry->d_sb);
> -       if (unlikely(!inode))
> +       if (unlikely(!inode)) {
> +               pr_err("out of free dentries, can not create automount '%s'\n",
> +                      name);
>                 return failed_creating(dentry);
> +       }
>
>         make_empty_dir_inode(inode);
>         inode->i_flags |= S_AUTOMOUNT;
> @@ -608,6 +621,8 @@ struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
>
>         inode = debugfs_get_inode(dentry->d_sb);
>         if (unlikely(!inode)) {
> +               pr_err("out of free dentries, can not create symlink '%s'\n",
> +                      name);
>                 kfree(link);
>                 return failed_creating(dentry);
>         }
> --
> 2.22.0
>

Re: [PATCH 2/2] debugfs: log errors when something goes wrong

[Greg Kroah-Hartman]

On Wed, Jul 03, 2019 at 11:10:44AM +0200, Rafael J. Wysocki wrote:
> On Wed, Jul 3, 2019 at 9:17 AM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > As it is not recommended that debugfs calls be checked, it was pointed
> > out that major errors should still be logged somewhere so that
> > developers and users have a chance to figure out what went wrong.  To
> > help with this, error logging has been added to the debugfs core so that
> > it is not needed to be present in every individual file that calls
> > debugfs.
> >
> > Reported-by: Mark Brown <broonie@kernel.org>
> > Reported-by: Takashi Iwai <tiwai@suse.de>
> > Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> Generally speaking
> 
> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> > ---
> >  fs/debugfs/inode.c | 25 ++++++++++++++++++++-----
> >  1 file changed, 20 insertions(+), 5 deletions(-)
> >
> > diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
> > index f04c8475d9a1..7f43c8acfcbf 100644
> > --- a/fs/debugfs/inode.c
> > +++ b/fs/debugfs/inode.c
> > @@ -2,8 +2,9 @@
> >  /*
> >   *  inode.c - part of debugfs, a tiny little debug file system
> >   *
> > - *  Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
> > + *  Copyright (C) 2004,2019 Greg Kroah-Hartman <greg@kroah.com>
> >   *  Copyright (C) 2004 IBM Inc.
> > + *  Copyright (C) 2019 Linux Foundation <gregkh@linuxfoundation.org>
> >   *
> >   *  debugfs is for people to use instead of /proc or /sys.
> >   *  See ./Documentation/core-api/kernel-api.rst for more details.
> > @@ -294,8 +295,10 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
> >
> >         error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
> >                               &debugfs_mount_count);
> > -       if (error)
> > +       if (error) {
> > +               pr_err("Unable to pin filesystem for file '%s'\n", name);
> 
> But I'm not sure about the log level here.  Particularly, why would
> pr_info() not work?

It could, but it is an error in that debugfs didn't do what was asked of
it.  I really don't care either way, the odds of anyone ever seeing this
message is almost none :)

thanks,

greg k-h

Re: [PATCH 2/2] debugfs: log errors when something goes wrong

[Takashi Iwai]

On Wed, 03 Jul 2019 11:32:33 +0200,
Greg Kroah-Hartman wrote:
> 
> On Wed, Jul 03, 2019 at 11:10:44AM +0200, Rafael J. Wysocki wrote:
> > On Wed, Jul 3, 2019 at 9:17 AM Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> wrote:
> > >
> > > As it is not recommended that debugfs calls be checked, it was pointed
> > > out that major errors should still be logged somewhere so that
> > > developers and users have a chance to figure out what went wrong.  To
> > > help with this, error logging has been added to the debugfs core so that
> > > it is not needed to be present in every individual file that calls
> > > debugfs.
> > >
> > > Reported-by: Mark Brown <broonie@kernel.org>
> > > Reported-by: Takashi Iwai <tiwai@suse.de>
> > > Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > 
> > Generally speaking
> > 
> > Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > 
> > > ---
> > >  fs/debugfs/inode.c | 25 ++++++++++++++++++++-----
> > >  1 file changed, 20 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
> > > index f04c8475d9a1..7f43c8acfcbf 100644
> > > --- a/fs/debugfs/inode.c
> > > +++ b/fs/debugfs/inode.c
> > > @@ -2,8 +2,9 @@
> > >  /*
> > >   *  inode.c - part of debugfs, a tiny little debug file system
> > >   *
> > > - *  Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
> > > + *  Copyright (C) 2004,2019 Greg Kroah-Hartman <greg@kroah.com>
> > >   *  Copyright (C) 2004 IBM Inc.
> > > + *  Copyright (C) 2019 Linux Foundation <gregkh@linuxfoundation.org>
> > >   *
> > >   *  debugfs is for people to use instead of /proc or /sys.
> > >   *  See ./Documentation/core-api/kernel-api.rst for more details.
> > > @@ -294,8 +295,10 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
> > >
> > >         error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
> > >                               &debugfs_mount_count);
> > > -       if (error)
> > > +       if (error) {
> > > +               pr_err("Unable to pin filesystem for file '%s'\n", name);
> > 
> > But I'm not sure about the log level here.  Particularly, why would
> > pr_info() not work?
> 
> It could, but it is an error in that debugfs didn't do what was asked of
> it.  I really don't care either way, the odds of anyone ever seeing this
> message is almost none :)

Yes, that's an obvious error and I see no big reason to hide it.

For both:
  Reviewed-by: Takashi Iwai <tiwai@suse.de>


Thanks!

Takashi

Re: [PATCH 2/2] debugfs: log errors when something goes wrong

[Greg Kroah-Hartman]

On Wed, Jul 03, 2019 at 11:35:50AM +0200, Takashi Iwai wrote:
> On Wed, 03 Jul 2019 11:32:33 +0200,
> Greg Kroah-Hartman wrote:
> > 
> > On Wed, Jul 03, 2019 at 11:10:44AM +0200, Rafael J. Wysocki wrote:
> > > On Wed, Jul 3, 2019 at 9:17 AM Greg Kroah-Hartman
> > > <gregkh@linuxfoundation.org> wrote:
> > > >
> > > > As it is not recommended that debugfs calls be checked, it was pointed
> > > > out that major errors should still be logged somewhere so that
> > > > developers and users have a chance to figure out what went wrong.  To
> > > > help with this, error logging has been added to the debugfs core so that
> > > > it is not needed to be present in every individual file that calls
> > > > debugfs.
> > > >
> > > > Reported-by: Mark Brown <broonie@kernel.org>
> > > > Reported-by: Takashi Iwai <tiwai@suse.de>
> > > > Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> > > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > > 
> > > Generally speaking
> > > 
> > > Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > > 
> > > > ---
> > > >  fs/debugfs/inode.c | 25 ++++++++++++++++++++-----
> > > >  1 file changed, 20 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
> > > > index f04c8475d9a1..7f43c8acfcbf 100644
> > > > --- a/fs/debugfs/inode.c
> > > > +++ b/fs/debugfs/inode.c
> > > > @@ -2,8 +2,9 @@
> > > >  /*
> > > >   *  inode.c - part of debugfs, a tiny little debug file system
> > > >   *
> > > > - *  Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
> > > > + *  Copyright (C) 2004,2019 Greg Kroah-Hartman <greg@kroah.com>
> > > >   *  Copyright (C) 2004 IBM Inc.
> > > > + *  Copyright (C) 2019 Linux Foundation <gregkh@linuxfoundation.org>
> > > >   *
> > > >   *  debugfs is for people to use instead of /proc or /sys.
> > > >   *  See ./Documentation/core-api/kernel-api.rst for more details.
> > > > @@ -294,8 +295,10 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
> > > >
> > > >         error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
> > > >                               &debugfs_mount_count);
> > > > -       if (error)
> > > > +       if (error) {
> > > > +               pr_err("Unable to pin filesystem for file '%s'\n", name);
> > > 
> > > But I'm not sure about the log level here.  Particularly, why would
> > > pr_info() not work?
> > 
> > It could, but it is an error in that debugfs didn't do what was asked of
> > it.  I really don't care either way, the odds of anyone ever seeing this
> > message is almost none :)
> 
> Yes, that's an obvious error and I see no big reason to hide it.
> 
> For both:
>   Reviewed-by: Takashi Iwai <tiwai@suse.de>

Thanks all for the review, I'll go apply these to my tree now.

greg k-h

Re: [PATCH 2/2] debugfs: log errors when something goes wrong

[Rafael J. Wysocki]

On Wed, Jul 3, 2019 at 11:32 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Wed, Jul 03, 2019 at 11:10:44AM +0200, Rafael J. Wysocki wrote:
> > On Wed, Jul 3, 2019 at 9:17 AM Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> wrote:
> > >
> > > As it is not recommended that debugfs calls be checked, it was pointed
> > > out that major errors should still be logged somewhere so that
> > > developers and users have a chance to figure out what went wrong.  To
> > > help with this, error logging has been added to the debugfs core so that
> > > it is not needed to be present in every individual file that calls
> > > debugfs.
> > >
> > > Reported-by: Mark Brown <broonie@kernel.org>
> > > Reported-by: Takashi Iwai <tiwai@suse.de>
> > > Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >
> > Generally speaking
> >
> > Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > > ---
> > >  fs/debugfs/inode.c | 25 ++++++++++++++++++++-----
> > >  1 file changed, 20 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
> > > index f04c8475d9a1..7f43c8acfcbf 100644
> > > --- a/fs/debugfs/inode.c
> > > +++ b/fs/debugfs/inode.c
> > > @@ -2,8 +2,9 @@
> > >  /*
> > >   *  inode.c - part of debugfs, a tiny little debug file system
> > >   *
> > > - *  Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
> > > + *  Copyright (C) 2004,2019 Greg Kroah-Hartman <greg@kroah.com>
> > >   *  Copyright (C) 2004 IBM Inc.
> > > + *  Copyright (C) 2019 Linux Foundation <gregkh@linuxfoundation.org>
> > >   *
> > >   *  debugfs is for people to use instead of /proc or /sys.
> > >   *  See ./Documentation/core-api/kernel-api.rst for more details.
> > > @@ -294,8 +295,10 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
> > >
> > >         error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
> > >                               &debugfs_mount_count);
> > > -       if (error)
> > > +       if (error) {
> > > +               pr_err("Unable to pin filesystem for file '%s'\n", name);
> >
> > But I'm not sure about the log level here.  Particularly, why would
> > pr_info() not work?
>
> It could, but it is an error in that debugfs didn't do what was asked of
> it.  I really don't care either way, the odds of anyone ever seeing this
> message is almost none :)

Fair enough.

Re: [PATCH 2/2] debugfs: log errors when something goes wrong

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 479 bytes --]

On Wed, Jul 03, 2019 at 09:16:53AM +0200, Greg Kroah-Hartman wrote:
> As it is not recommended that debugfs calls be checked, it was pointed
> out that major errors should still be logged somewhere so that
> developers and users have a chance to figure out what went wrong.  To
> help with this, error logging has been added to the debugfs core so that
> it is not needed to be present in every individual file that calls
> debugfs.

Reviewed-by: Mark Brown <broonie@kernel.org>

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Re: [PATCH 1/2] debugfs: provide pr_fmt() macro

[Rafael J. Wysocki]

On Wed, Jul 3, 2019 at 9:17 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> Use a common "debugfs: " prefix for all pr_* calls in a single place.
>
> Cc: Mark Brown <broonie@kernel.org>
> Cc: Takashi Iwai <tiwai@suse.de>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
>  fs/debugfs/inode.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
> index acef14ad53db..f04c8475d9a1 100644
> --- a/fs/debugfs/inode.c
> +++ b/fs/debugfs/inode.c
> @@ -9,6 +9,8 @@
>   *  See ./Documentation/core-api/kernel-api.rst for more details.
>   */
>
> +#define pr_fmt(fmt)    "debugfs: " fmt
> +
>  #include <linux/module.h>
>  #include <linux/fs.h>
>  #include <linux/mount.h>
> @@ -285,7 +287,7 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
>         struct dentry *dentry;
>         int error;
>
> -       pr_debug("debugfs: creating file '%s'\n",name);
> +       pr_debug("creating file '%s'\n", name);
>
>         if (IS_ERR(parent))
>                 return parent;
> --
> 2.22.0
>