[PATCH 2/2] intel_pmc_core: avoid boot time warning for !CONFIG_DEBUGFS_FS

[PATCH 2/2] intel_pmc_core: avoid boot time warning for !CONFIG_DEBUGFS_FS

[Arnd Bergmann]

While looking at a patch that introduced a compile-time warning
"‘pmc_core_dev_state_get’ defined but not used" (I sent a patch
for debugfs to fix it), I noticed that the same patch caused
it in intel_pmc_core also introduced a bogus run-time warning:
"PMC Core: debugfs register failed".

The problem is the IS_ERR_OR_NULL() check that as usual gets
things wrong: when CONFIG_DEBUGFS_FS is disabled,
debugfs_create_dir() fails with an error code, and we don't
need to warn about it, unlike the case in which it returns
NULL.

This reverts the driver to the previous state of not warning
about CONFIG_DEBUGFS_FS being disabled. I chose not to
restore the driver to making a runtime error in debugfs
fatal in pmc_core_probe().

Fixes: df2294fb6428 ("intel_pmc_core: Convert to DEFINE_DEBUGFS_ATTRIBUTE")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/platform/x86/intel_pmc_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/platform/x86/intel_pmc_core.c b/drivers/platform/x86/intel_pmc_core.c
index 520b58a04daa..e8b1b836ca2d 100644
--- a/drivers/platform/x86/intel_pmc_core.c
+++ b/drivers/platform/x86/intel_pmc_core.c
@@ -100,7 +100,7 @@ static int pmc_core_dbgfs_register(struct pmc_dev *pmcdev)
 	struct dentry *dir, *file;
 
 	dir = debugfs_create_dir("pmc_core", NULL);
-	if (IS_ERR_OR_NULL(dir))
+	if (!dir)
 		return -ENOMEM;
 
 	pmcdev->dbgfs_dir = dir;
-- 
2.9.0

Re: [PATCH 2/2] intel_pmc_core: avoid boot time warning for !CONFIG_DEBUGFS_FS

[Greg Kroah-Hartman]

On Mon, Oct 10, 2016 at 01:12:58PM +0200, Arnd Bergmann wrote:
> While looking at a patch that introduced a compile-time warning
> "‘pmc_core_dev_state_get’ defined but not used" (I sent a patch
> for debugfs to fix it), I noticed that the same patch caused
> it in intel_pmc_core also introduced a bogus run-time warning:
> "PMC Core: debugfs register failed".
> 
> The problem is the IS_ERR_OR_NULL() check that as usual gets
> things wrong: when CONFIG_DEBUGFS_FS is disabled,
> debugfs_create_dir() fails with an error code, and we don't
> need to warn about it, unlike the case in which it returns
> NULL.
> 
> This reverts the driver to the previous state of not warning
> about CONFIG_DEBUGFS_FS being disabled. I chose not to
> restore the driver to making a runtime error in debugfs
> fatal in pmc_core_probe().
> 
> Fixes: df2294fb6428 ("intel_pmc_core: Convert to DEFINE_DEBUGFS_ATTRIBUTE")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/platform/x86/intel_pmc_core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/intel_pmc_core.c b/drivers/platform/x86/intel_pmc_core.c
> index 520b58a04daa..e8b1b836ca2d 100644
> --- a/drivers/platform/x86/intel_pmc_core.c
> +++ b/drivers/platform/x86/intel_pmc_core.c
> @@ -100,7 +100,7 @@ static int pmc_core_dbgfs_register(struct pmc_dev *pmcdev)
>  	struct dentry *dir, *file;
>  
>  	dir = debugfs_create_dir("pmc_core", NULL);
> -	if (IS_ERR_OR_NULL(dir))
> +	if (!dir)
>  		return -ENOMEM;

Hah, no, you shouldn't ever care about any return value being "wrong"
from debugfs, the code should just continue on as normal.

And yes, you are correct, the IS_ERR_OR_NULL() is totally wrong.

thanks,

greg k-h

Re: [PATCH 2/2] intel_pmc_core: avoid boot time warning for !CONFIG_DEBUGFS_FS

[Darren Hart]

On Mon, Oct 10, 2016 at 02:29:17PM +0200, Greg Kroah-Hartman wrote:
> On Mon, Oct 10, 2016 at 01:12:58PM +0200, Arnd Bergmann wrote:
> > While looking at a patch that introduced a compile-time warning
> > "‘pmc_core_dev_state_get’ defined but not used" (I sent a patch
> > for debugfs to fix it), I noticed that the same patch caused
> > it in intel_pmc_core also introduced a bogus run-time warning:
> > "PMC Core: debugfs register failed".
> > 
> > The problem is the IS_ERR_OR_NULL() check that as usual gets
> > things wrong: when CONFIG_DEBUGFS_FS is disabled,
> > debugfs_create_dir() fails with an error code, and we don't
> > need to warn about it, unlike the case in which it returns
> > NULL.
> > 
> > This reverts the driver to the previous state of not warning
> > about CONFIG_DEBUGFS_FS being disabled. I chose not to
> > restore the driver to making a runtime error in debugfs
> > fatal in pmc_core_probe().
> > 
> > Fixes: df2294fb6428 ("intel_pmc_core: Convert to DEFINE_DEBUGFS_ATTRIBUTE")
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> >  drivers/platform/x86/intel_pmc_core.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/platform/x86/intel_pmc_core.c b/drivers/platform/x86/intel_pmc_core.c
> > index 520b58a04daa..e8b1b836ca2d 100644
> > --- a/drivers/platform/x86/intel_pmc_core.c
> > +++ b/drivers/platform/x86/intel_pmc_core.c
> > @@ -100,7 +100,7 @@ static int pmc_core_dbgfs_register(struct pmc_dev *pmcdev)
> >  	struct dentry *dir, *file;
> >  
> >  	dir = debugfs_create_dir("pmc_core", NULL);
> > -	if (IS_ERR_OR_NULL(dir))
> > +	if (!dir)
> >  		return -ENOMEM;
> 
> Hah, no, you shouldn't ever care about any return value being "wrong"
> from debugfs, the code should just continue on as normal.
> 
> And yes, you are correct, the IS_ERR_OR_NULL() is totally wrong.
> 
> thanks,
> 
> greg k-h
> 

Thanks Arnd and Greg, appreciate the catch and the fix.

Applied.

-- 
Darren Hart
Intel Open Source Technology Center