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[PATCH v2 2/9] pwm: lpss: Move exported symbols to PWM_LPSS namespace

Andy Shevchenko posted 9 patches 3 years, 6 months ago
There is a newer version of this series
[PATCH v2 2/9] pwm: lpss: Move exported symbols to PWM_LPSS namespace
Posted by Andy Shevchenko 3 years, 6 months ago 
Avoid unnecessary pollution of the global symbol namespace by
moving library functions in to a specific namespace and import
that into the drivers that make use of the functions.

For more info: https://lwn.net/Articles/760045/

Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/pwm/pwm-lpss-pci.c      | 1 +
 drivers/pwm/pwm-lpss-platform.c | 1 +
 drivers/pwm/pwm-lpss.c          | 2 ++
 3 files changed, 4 insertions(+)

diff --git a/drivers/pwm/pwm-lpss-pci.c b/drivers/pwm/pwm-lpss-pci.c
index 75b778e839b3..9f2c666b95ec 100644
--- a/drivers/pwm/pwm-lpss-pci.c
+++ b/drivers/pwm/pwm-lpss-pci.c
@@ -92,3 +92,4 @@ module_pci_driver(pwm_lpss_driver_pci);
 
 MODULE_DESCRIPTION("PWM PCI driver for Intel LPSS");
 MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS(PWM_LPSS);
diff --git a/drivers/pwm/pwm-lpss-platform.c b/drivers/pwm/pwm-lpss-platform.c
index 834423c34f48..65154c0abab1 100644
--- a/drivers/pwm/pwm-lpss-platform.c
+++ b/drivers/pwm/pwm-lpss-platform.c
@@ -88,4 +88,5 @@ module_platform_driver(pwm_lpss_driver_platform);
 
 MODULE_DESCRIPTION("PWM platform driver for Intel LPSS");
 MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS(PWM_LPSS);
 MODULE_ALIAS("platform:pwm-lpss");
diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
index 9537aefd254a..74a296cb1af0 100644
--- a/drivers/pwm/pwm-lpss.c
+++ b/drivers/pwm/pwm-lpss.c
@@ -18,6 +18,8 @@
 #include <linux/pm_runtime.h>
 #include <linux/time.h>
 
+#define DEFAULT_SYMBOL_NAMESPACE PWM_LPSS
+
 #include "pwm-lpss.h"
 
 #define PWM				0x00000000
-- 
2.35.1
Re: [PATCH v2 2/9] pwm: lpss: Move exported symbols to PWM_LPSS namespace
Posted by Uwe Kleine-König 3 years, 6 months ago 
Hello,

On Thu, Sep 08, 2022 at 04:56:51PM +0300, Andy Shevchenko wrote:
> Avoid unnecessary pollution of the global symbol namespace by
> moving library functions in to a specific namespace and import
> that into the drivers that make use of the functions.
> 
> For more info: https://lwn.net/Articles/760045/
> 
> Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  drivers/pwm/pwm-lpss-pci.c      | 1 +
>  drivers/pwm/pwm-lpss-platform.c | 1 +
>  drivers/pwm/pwm-lpss.c          | 2 ++
>  3 files changed, 4 insertions(+)
> 
> diff --git a/drivers/pwm/pwm-lpss-pci.c b/drivers/pwm/pwm-lpss-pci.c
> index 75b778e839b3..9f2c666b95ec 100644
> --- a/drivers/pwm/pwm-lpss-pci.c
> +++ b/drivers/pwm/pwm-lpss-pci.c
> @@ -92,3 +92,4 @@ module_pci_driver(pwm_lpss_driver_pci);
>  
>  MODULE_DESCRIPTION("PWM PCI driver for Intel LPSS");
>  MODULE_LICENSE("GPL v2");
> +MODULE_IMPORT_NS(PWM_LPSS);

Each user of the lpss.h header needs that, right? Then the
MODULE_IMPORT_NS statement can go into the header, too.

Even without this change:

Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Thanks
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |
Re: [PATCH v2 2/9] pwm: lpss: Move exported symbols to PWM_LPSS namespace
Posted by Andy Shevchenko 3 years, 6 months ago 
On Sat, Sep 24, 2022 at 11:59:45AM +0200, Uwe Kleine-König wrote:
> Hello,
> 
> On Thu, Sep 08, 2022 at 04:56:51PM +0300, Andy Shevchenko wrote:
> > Avoid unnecessary pollution of the global symbol namespace by
> > moving library functions in to a specific namespace and import
> > that into the drivers that make use of the functions.
> > 
> > For more info: https://lwn.net/Articles/760045/
> > 
> > Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > ---
> >  drivers/pwm/pwm-lpss-pci.c      | 1 +
> >  drivers/pwm/pwm-lpss-platform.c | 1 +
> >  drivers/pwm/pwm-lpss.c          | 2 ++
> >  3 files changed, 4 insertions(+)
> > 
> > diff --git a/drivers/pwm/pwm-lpss-pci.c b/drivers/pwm/pwm-lpss-pci.c
> > index 75b778e839b3..9f2c666b95ec 100644
> > --- a/drivers/pwm/pwm-lpss-pci.c
> > +++ b/drivers/pwm/pwm-lpss-pci.c
> > @@ -92,3 +92,4 @@ module_pci_driver(pwm_lpss_driver_pci);
> >  
> >  MODULE_DESCRIPTION("PWM PCI driver for Intel LPSS");
> >  MODULE_LICENSE("GPL v2");
> > +MODULE_IMPORT_NS(PWM_LPSS);
> 
> Each user of the lpss.h header needs that, right? Then the
> MODULE_IMPORT_NS statement can go into the header, too.

With the same answer as for v1: any user that might include the header for
the sake of data types will get the NS inclusion even if they don't need
that (yes, I don't think it's practical, but slightly better to make sure
that if one uses an API, one adds necessary NS inclusions; also note that
in case of stale header inclusion this again might bring unnecessary NS,
while the header should be removed -- with that being said, I think we
might need some kind of extended includecheck to see if the APIs and data
structures are actually used when a certain header is included).

> Even without this change:
> 
> Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Thanks!


-- 
With Best Regards,
Andy Shevchenko
Re: [PATCH v2 2/9] pwm: lpss: Move exported symbols to PWM_LPSS namespace
Posted by Uwe Kleine-König 3 years, 6 months ago 
On Mon, Sep 26, 2022 at 12:43:47PM +0300, Andy Shevchenko wrote:
> On Sat, Sep 24, 2022 at 11:59:45AM +0200, Uwe Kleine-König wrote:
> > Hello,
> > 
> > On Thu, Sep 08, 2022 at 04:56:51PM +0300, Andy Shevchenko wrote:
> > > Avoid unnecessary pollution of the global symbol namespace by
> > > moving library functions in to a specific namespace and import
> > > that into the drivers that make use of the functions.
> > > 
> > > For more info: https://lwn.net/Articles/760045/
> > > 
> > > Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > > ---
> > >  drivers/pwm/pwm-lpss-pci.c      | 1 +
> > >  drivers/pwm/pwm-lpss-platform.c | 1 +
> > >  drivers/pwm/pwm-lpss.c          | 2 ++
> > >  3 files changed, 4 insertions(+)
> > > 
> > > diff --git a/drivers/pwm/pwm-lpss-pci.c b/drivers/pwm/pwm-lpss-pci.c
> > > index 75b778e839b3..9f2c666b95ec 100644
> > > --- a/drivers/pwm/pwm-lpss-pci.c
> > > +++ b/drivers/pwm/pwm-lpss-pci.c
> > > @@ -92,3 +92,4 @@ module_pci_driver(pwm_lpss_driver_pci);
> > >  
> > >  MODULE_DESCRIPTION("PWM PCI driver for Intel LPSS");
> > >  MODULE_LICENSE("GPL v2");
> > > +MODULE_IMPORT_NS(PWM_LPSS);
> > 
> > Each user of the lpss.h header needs that, right? Then the
> > MODULE_IMPORT_NS statement can go into the header, too.
> 
> With the same answer as for v1: any user that might include the header for
> the sake of data types will get the NS inclusion even if they don't need
> that (yes, I don't think it's practical, but slightly better to make sure

I'm not sure I understand you correctly here. For some headers you
cannot assume that a file including the header also needs the namespace
macro, but for pwm-lpss.h that should be a safe assumption.

> that if one uses an API, one adds necessary NS inclusions; also note that
> in case of stale header inclusion this again might bring unnecessary NS,
> while the header should be removed -- with that being said, I think we
> might need some kind of extended includecheck to see if the APIs and data
> structures are actually used when a certain header is included).

+1 for a check about unused headers.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |
Re: [PATCH v2 2/9] pwm: lpss: Move exported symbols to PWM_LPSS namespace
Posted by Andy Shevchenko 3 years, 6 months ago 
On Mon, Sep 26, 2022 at 11:55:47AM +0200, Uwe Kleine-König wrote:
> On Mon, Sep 26, 2022 at 12:43:47PM +0300, Andy Shevchenko wrote:
> > On Sat, Sep 24, 2022 at 11:59:45AM +0200, Uwe Kleine-König wrote:
> > > On Thu, Sep 08, 2022 at 04:56:51PM +0300, Andy Shevchenko wrote:

...

> > > > +MODULE_IMPORT_NS(PWM_LPSS);
> > > 
> > > Each user of the lpss.h header needs that, right? Then the
> > > MODULE_IMPORT_NS statement can go into the header, too.
> > 
> > With the same answer as for v1: any user that might include the header for
> > the sake of data types will get the NS inclusion even if they don't need
> > that (yes, I don't think it's practical, but slightly better to make sure
> 
> I'm not sure I understand you correctly here. For some headers you
> cannot assume that a file including the header also needs the namespace
> macro, but for pwm-lpss.h that should be a safe assumption.

Yes, it's a safe assumption for _this_ case (as I pointed out above that
there is probably no practical to assume otherwise), in general it may be
not the case.

-- 
With Best Regards,
Andy Shevchenko

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