[PATCH] staging: comedi: Optimize code using logical short-circuiting

[PATCH] staging: comedi: Optimize code using logical short-circuiting

[Namrata A Shettar]

Optimize code using logical short-circuiting. Two if statements
having same return value is equivalent to a single if statement with
condition being the union of the prior two.

Signed-off-by: Namrata A Shettar <namrataashettar@gmail.com>
---
 drivers/staging/comedi/comedi_fops.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index 1999eed..0d69ed7 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -791,9 +791,7 @@ static int is_device_busy(struct comedi_device *dev)
 
 	for (i = 0; i < dev->n_subdevices; i++) {
 		s = &dev->subdevices[i];
-		if (s->busy)
-			return 1;
-		if (s->async && comedi_buf_is_mmapped(s))
+		if (s->busy || (s->async && comedi_buf_is_mmapped(s)))
 			return 1;
 	}
 
-- 
2.7.4

Re: [PATCH] staging: comedi: Optimize code using logical short-circuiting

[Greg Kroah-Hartman]

On Sat, Sep 17, 2016 at 12:54:59AM +0530, Namrata A Shettar wrote:
> Optimize code using logical short-circuiting. Two if statements
> having same return value is equivalent to a single if statement with
> condition being the union of the prior two.
> 
> Signed-off-by: Namrata A Shettar <namrataashettar@gmail.com>
> ---
>  drivers/staging/comedi/comedi_fops.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
> index 1999eed..0d69ed7 100644
> --- a/drivers/staging/comedi/comedi_fops.c
> +++ b/drivers/staging/comedi/comedi_fops.c
> @@ -791,9 +791,7 @@ static int is_device_busy(struct comedi_device *dev)
>  
>  	for (i = 0; i < dev->n_subdevices; i++) {
>  		s = &dev->subdevices[i];
> -		if (s->busy)
> -			return 1;
> -		if (s->async && comedi_buf_is_mmapped(s))
> +		if (s->busy || (s->async && comedi_buf_is_mmapped(s)))
>  			return 1;

The original code was easier to read.

We write kernel code for developers first, and the compiler second.  In
either case, the compiler will create the same output, you haven't
really saved any logic or speed here.  You have made it harder to read
and follow, so I will have to reject this change, sorry.

thanks,

greg k-h

Re: [PATCH] staging: comedi: Optimize code using logical short-circuiting

[Namrata A Shettar]

On Sat, Sep 17, 2016 at 08:35:22PM +0200, Greg Kroah-Hartman wrote:
> On Sat, Sep 17, 2016 at 12:54:59AM +0530, Namrata A Shettar wrote:
> > Optimize code using logical short-circuiting. Two if statements
> > having same return value is equivalent to a single if statement with
> > condition being the union of the prior two.
> > 
> > Signed-off-by: Namrata A Shettar <namrataashettar@gmail.com>
> > ---
> >  drivers/staging/comedi/comedi_fops.c | 4 +---
> >  1 file changed, 1 insertion(+), 3 deletions(-)
> > 
> > diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
> > index 1999eed..0d69ed7 100644
> > --- a/drivers/staging/comedi/comedi_fops.c
> > +++ b/drivers/staging/comedi/comedi_fops.c
> > @@ -791,9 +791,7 @@ static int is_device_busy(struct comedi_device *dev)
> >  
> >  	for (i = 0; i < dev->n_subdevices; i++) {
> >  		s = &dev->subdevices[i];
> > -		if (s->busy)
> > -			return 1;
> > -		if (s->async && comedi_buf_is_mmapped(s))
> > +		if (s->busy || (s->async && comedi_buf_is_mmapped(s)))
> >  			return 1;
> 
> The original code was easier to read.
> 
> We write kernel code for developers first, and the compiler second.  In
> either case, the compiler will create the same output, you haven't
> really saved any logic or speed here.  You have made it harder to read
> and follow, so I will have to reject this change, sorry.
> 
> thanks,
> 
> greg k-h

Got that! will keep that in mind the next time around I plan making such
a change.

thanks,

namrata