[PATCH] power: domain: no need to check return value of debugfs_create functions

[PATCH] power: domain: no need to check return value of debugfs_create functions

[Greg Kroah-Hartman]

When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Kevin Hilman <khilman@kernel.org>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Len Brown <len.brown@intel.com>
Cc: linux-pm@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/base/power/domain.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 500de1dee967..45eafe8cf7dd 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -2948,18 +2948,11 @@ static int __init genpd_debug_init(void)
 
 	genpd_debugfs_dir = debugfs_create_dir("pm_genpd", NULL);
 
-	if (!genpd_debugfs_dir)
-		return -ENOMEM;
-
-	d = debugfs_create_file("pm_genpd_summary", S_IRUGO,
-			genpd_debugfs_dir, NULL, &summary_fops);
-	if (!d)
-		return -ENOMEM;
+	debugfs_create_file("pm_genpd_summary", S_IRUGO, genpd_debugfs_dir,
+			    NULL, &summary_fops);
 
 	list_for_each_entry(genpd, &gpd_list, gpd_list_node) {
 		d = debugfs_create_dir(genpd->name, genpd_debugfs_dir);
-		if (!d)
-			return -ENOMEM;
 
 		debugfs_create_file("current_state", 0444,
 				d, genpd, &status_fops);
-- 
2.20.1

Re: [PATCH] power: domain: no need to check return value of debugfs_create functions

[Ulf Hansson]

On Tue, 22 Jan 2019 at 16:23, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> When calling debugfs functions, there is no need to ever check the
> return value.  The function can work or not, but the code logic should
> never do something different based on this.

Doesn't this boils done to whether we want to care to check if memory
allocation failed?

Somewhere down the call chain from debugfs_create_dir(), we end up in
alloc_inode() and it looks like that can fail, no?

Kind regards
Uffe

>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Kevin Hilman <khilman@kernel.org>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: Len Brown <len.brown@intel.com>
> Cc: linux-pm@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/base/power/domain.c | 11 ++---------
>  1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 500de1dee967..45eafe8cf7dd 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2948,18 +2948,11 @@ static int __init genpd_debug_init(void)
>
>         genpd_debugfs_dir = debugfs_create_dir("pm_genpd", NULL);
>
> -       if (!genpd_debugfs_dir)
> -               return -ENOMEM;
> -
> -       d = debugfs_create_file("pm_genpd_summary", S_IRUGO,
> -                       genpd_debugfs_dir, NULL, &summary_fops);
> -       if (!d)
> -               return -ENOMEM;
> +       debugfs_create_file("pm_genpd_summary", S_IRUGO, genpd_debugfs_dir,
> +                           NULL, &summary_fops);
>
>         list_for_each_entry(genpd, &gpd_list, gpd_list_node) {
>                 d = debugfs_create_dir(genpd->name, genpd_debugfs_dir);
> -               if (!d)
> -                       return -ENOMEM;
>
>                 debugfs_create_file("current_state", 0444,
>                                 d, genpd, &status_fops);
> --
> 2.20.1
>

Re: [PATCH] power: domain: no need to check return value of debugfs_create functions

[Greg Kroah-Hartman]

On Wed, Jan 23, 2019 at 08:44:36AM +0100, Ulf Hansson wrote:
> On Tue, 22 Jan 2019 at 16:23, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > When calling debugfs functions, there is no need to ever check the
> > return value.  The function can work or not, but the code logic should
> > never do something different based on this.
> 
> Doesn't this boils done to whether we want to care to check if memory
> allocation failed?

You should not care.

> Somewhere down the call chain from debugfs_create_dir(), we end up in
> alloc_inode() and it looks like that can fail, no?

Yes it can, right now it will return NULL, I'll go change that to return
ENOMEM, but even then, your really do not care what happens as none of
your other code flow should ever care about what debugfs does, or does
not, do.

thanks,

greg k-h

Re: [PATCH] power: domain: no need to check return value of debugfs_create functions

[Ulf Hansson]

On Wed, 23 Jan 2019 at 08:59, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Wed, Jan 23, 2019 at 08:44:36AM +0100, Ulf Hansson wrote:
> > On Tue, 22 Jan 2019 at 16:23, Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> wrote:
> > >
> > > When calling debugfs functions, there is no need to ever check the
> > > return value.  The function can work or not, but the code logic should
> > > never do something different based on this.
> >
> > Doesn't this boils done to whether we want to care to check if memory
> > allocation failed?
>
> You should not care.

Okay.

>
> > Somewhere down the call chain from debugfs_create_dir(), we end up in
> > alloc_inode() and it looks like that can fail, no?
>
> Yes it can, right now it will return NULL, I'll go change that to return
> ENOMEM, but even then, your really do not care what happens as none of
> your other code flow should ever care about what debugfs does, or does
> not, do.

In that case, why don't we convert the debugfs_create_dir() and
friends, to becomes "void" functions? Or maybe that's your plan going
forward?

Kind regards
Uffe

Re: [PATCH] power: domain: no need to check return value of debugfs_create functions

[Greg Kroah-Hartman]

On Wed, Jan 23, 2019 at 09:20:05AM +0100, Ulf Hansson wrote:
> On Wed, 23 Jan 2019 at 08:59, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > On Wed, Jan 23, 2019 at 08:44:36AM +0100, Ulf Hansson wrote:
> > > On Tue, 22 Jan 2019 at 16:23, Greg Kroah-Hartman
> > > <gregkh@linuxfoundation.org> wrote:
> > > >
> > > > When calling debugfs functions, there is no need to ever check the
> > > > return value.  The function can work or not, but the code logic should
> > > > never do something different based on this.
> > >
> > > Doesn't this boils done to whether we want to care to check if memory
> > > allocation failed?
> >
> > You should not care.
> 
> Okay.
> 
> >
> > > Somewhere down the call chain from debugfs_create_dir(), we end up in
> > > alloc_inode() and it looks like that can fail, no?
> >
> > Yes it can, right now it will return NULL, I'll go change that to return
> > ENOMEM, but even then, your really do not care what happens as none of
> > your other code flow should ever care about what debugfs does, or does
> > not, do.
> 
> In that case, why don't we convert the debugfs_create_dir() and
> friends, to becomes "void" functions? Or maybe that's your plan going
> forward?

I can't, as sometimes you actually care about using the return value in
another debugfs call.

thanks,

greg k-h

Re: [PATCH] power: domain: no need to check return value of debugfs_create functions

[Ulf Hansson]

On Tue, 22 Jan 2019 at 16:23, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> When calling debugfs functions, there is no need to ever check the
> return value.  The function can work or not, but the code logic should
> never do something different based on this.
>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Kevin Hilman <khilman@kernel.org>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: Len Brown <len.brown@intel.com>
> Cc: linux-pm@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Kind regards
Uffe

> ---
>  drivers/base/power/domain.c | 11 ++---------
>  1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 500de1dee967..45eafe8cf7dd 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2948,18 +2948,11 @@ static int __init genpd_debug_init(void)
>
>         genpd_debugfs_dir = debugfs_create_dir("pm_genpd", NULL);
>
> -       if (!genpd_debugfs_dir)
> -               return -ENOMEM;
> -
> -       d = debugfs_create_file("pm_genpd_summary", S_IRUGO,
> -                       genpd_debugfs_dir, NULL, &summary_fops);
> -       if (!d)
> -               return -ENOMEM;
> +       debugfs_create_file("pm_genpd_summary", S_IRUGO, genpd_debugfs_dir,
> +                           NULL, &summary_fops);
>
>         list_for_each_entry(genpd, &gpd_list, gpd_list_node) {
>                 d = debugfs_create_dir(genpd->name, genpd_debugfs_dir);
> -               if (!d)
> -                       return -ENOMEM;
>
>                 debugfs_create_file("current_state", 0444,
>                                 d, genpd, &status_fops);
> --
> 2.20.1
>

Re: [PATCH] power: domain: no need to check return value of debugfs_create functions

[Rafael J. Wysocki]

On Wednesday, January 23, 2019 1:49:00 PM CET Ulf Hansson wrote:
> On Tue, 22 Jan 2019 at 16:23, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > When calling debugfs functions, there is no need to ever check the
> > return value.  The function can work or not, but the code logic should
> > never do something different based on this.
> >
> > Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> > Cc: Kevin Hilman <khilman@kernel.org>
> > Cc: Ulf Hansson <ulf.hansson@linaro.org>
> > Cc: Len Brown <len.brown@intel.com>
> > Cc: linux-pm@vger.kernel.org
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Patch applied, thanks!