2019-05-23 13:25:28

by Nishka Dasgupta

[permalink] [raw]
Subject: [PATCH] staging: most: usb: Remove variable frame_size

Remove variable frame_size as its multiple usages are all independent of
each other and so can be returned separately.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <[email protected]>
---
drivers/staging/most/usb/usb.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/staging/most/usb/usb.c b/drivers/staging/most/usb/usb.c
index 360cb5b7a10b..751e82cf66c5 100644
--- a/drivers/staging/most/usb/usb.c
+++ b/drivers/staging/most/usb/usb.c
@@ -186,32 +186,28 @@ static inline int start_sync_ep(struct usb_device *usb_dev, u16 ep)
*/
static unsigned int get_stream_frame_size(struct most_channel_config *cfg)
{
- unsigned int frame_size = 0;
unsigned int sub_size = cfg->subbuffer_size;

if (!sub_size) {
pr_warn("Misconfig: Subbuffer size zero.\n");
- return frame_size;
+ return 0;
}
switch (cfg->data_type) {
case MOST_CH_ISOC:
- frame_size = AV_PACKETS_PER_XACT * sub_size;
- break;
+ return AV_PACKETS_PER_XACT * sub_size;
case MOST_CH_SYNC:
if (cfg->packets_per_xact == 0) {
pr_warn("Misconfig: Packets per XACT zero\n");
- frame_size = 0;
+ return 0;
} else if (cfg->packets_per_xact == 0xFF) {
- frame_size = (USB_MTU / sub_size) * sub_size;
+ return (USB_MTU / sub_size) * sub_size;
} else {
- frame_size = cfg->packets_per_xact * sub_size;
+ return cfg->packets_per_xact * sub_size;
}
- break;
default:
pr_warn("Query frame size of non-streaming channel\n");
- break;
+ return 0;
}
- return frame_size;
}

/**
--
2.19.1


2019-05-23 17:00:16

by Greg KH

[permalink] [raw]
Subject: Re: [PATCH] staging: most: usb: Remove variable frame_size

On Thu, May 23, 2019 at 06:53:34PM +0530, Nishka Dasgupta wrote:
> Remove variable frame_size as its multiple usages are all independent of
> each other and so can be returned separately.
> Issue found with Coccinelle.
>
> Signed-off-by: Nishka Dasgupta <[email protected]>
> ---
> drivers/staging/most/usb/usb.c | 16 ++++++----------
> 1 file changed, 6 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/staging/most/usb/usb.c b/drivers/staging/most/usb/usb.c
> index 360cb5b7a10b..751e82cf66c5 100644
> --- a/drivers/staging/most/usb/usb.c
> +++ b/drivers/staging/most/usb/usb.c
> @@ -186,32 +186,28 @@ static inline int start_sync_ep(struct usb_device *usb_dev, u16 ep)
> */
> static unsigned int get_stream_frame_size(struct most_channel_config *cfg)
> {
> - unsigned int frame_size = 0;
> unsigned int sub_size = cfg->subbuffer_size;
>
> if (!sub_size) {
> pr_warn("Misconfig: Subbuffer size zero.\n");
> - return frame_size;
> + return 0;
> }
> switch (cfg->data_type) {
> case MOST_CH_ISOC:
> - frame_size = AV_PACKETS_PER_XACT * sub_size;
> - break;
> + return AV_PACKETS_PER_XACT * sub_size;
> case MOST_CH_SYNC:
> if (cfg->packets_per_xact == 0) {
> pr_warn("Misconfig: Packets per XACT zero\n");
> - frame_size = 0;
> + return 0;
> } else if (cfg->packets_per_xact == 0xFF) {
> - frame_size = (USB_MTU / sub_size) * sub_size;
> + return (USB_MTU / sub_size) * sub_size;
> } else {
> - frame_size = cfg->packets_per_xact * sub_size;
> + return cfg->packets_per_xact * sub_size;
> }
> - break;
> default:
> pr_warn("Query frame size of non-streaming channel\n");
> - break;
> + return 0;
> }
> - return frame_size;
> }

Now it just feels like you are doing "busy work" :(

frame_size makes sense here, right? Why change this code?

Remember, code is written for developers first, the compiler second.
Reading this with frame_size makes it much more obvious what this code
does when you read it again in 5-10 years. Why change this, you have
not made it faster, or smaller at all.

So no, I would not accept this, sorry.

We have so many _real_ things to do in the drivers/staging/ directory if
you are looking for stuff to clean up. Don't try to micro-optimize
things that do not matter at the expense of understanding.

thanks,

greg k-h

2019-05-24 07:46:49

by Christian Gromm

[permalink] [raw]
Subject: Re: [PATCH] staging: most: usb: Remove variable frame_size

On Do, 2019-05-23 at 18:53 +0530, Nishka Dasgupta wrote:
> External E-Mail
>
>
> Remove variable frame_size as its multiple usages are all independent
> of
> each other and so can be returned separately.
> Issue found with Coccinelle.
>
> Signed-off-by: Nishka Dasgupta <[email protected]>

Acked-by: Christian Gromm <[email protected]>

> ---
>  drivers/staging/most/usb/usb.c | 16 ++++++----------
>  1 file changed, 6 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/staging/most/usb/usb.c
> b/drivers/staging/most/usb/usb.c
> index 360cb5b7a10b..751e82cf66c5 100644
> --- a/drivers/staging/most/usb/usb.c
> +++ b/drivers/staging/most/usb/usb.c
> @@ -186,32 +186,28 @@ static inline int start_sync_ep(struct
> usb_device *usb_dev, u16 ep)
>   */
>  static unsigned int get_stream_frame_size(struct most_channel_config
> *cfg)
>  {
> - unsigned int frame_size = 0;
>   unsigned int sub_size = cfg->subbuffer_size;
>  
>   if (!sub_size) {
>   pr_warn("Misconfig: Subbuffer size zero.\n");
> - return frame_size;
> + return 0;
>   }
>   switch (cfg->data_type) {
>   case MOST_CH_ISOC:
> - frame_size = AV_PACKETS_PER_XACT * sub_size;
> - break;
> + return AV_PACKETS_PER_XACT * sub_size;
>   case MOST_CH_SYNC:
>   if (cfg->packets_per_xact == 0) {
>   pr_warn("Misconfig: Packets per XACT
> zero\n");
> - frame_size = 0;
> + return 0;
>   } else if (cfg->packets_per_xact == 0xFF) {
> - frame_size = (USB_MTU / sub_size) *
> sub_size;
> + return (USB_MTU / sub_size) * sub_size;
>   } else {
> - frame_size = cfg->packets_per_xact *
> sub_size;
> + return cfg->packets_per_xact * sub_size;
>   }
> - break;
>   default:
>   pr_warn("Query frame size of non-streaming
> channel\n");
> - break;
> + return 0;
>   }
> - return frame_size;
>  }
>  
>  /**

2019-05-24 08:26:52

by Christian Gromm

[permalink] [raw]
Subject: Re: [PATCH] staging: most: usb: Remove variable frame_size

On Do, 2019-05-23 at 18:51 +0200, Greg KH wrote:
> External E-Mail
>
>
> On Thu, May 23, 2019 at 06:53:34PM +0530, Nishka Dasgupta wrote:
> >
> > Remove variable frame_size as its multiple usages are all
> > independent of
> > each other and so can be returned separately.
> > Issue found with Coccinelle.
> >
> > Signed-off-by: Nishka Dasgupta <[email protected]>
> > ---
> >  drivers/staging/most/usb/usb.c | 16 ++++++----------
> >  1 file changed, 6 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/staging/most/usb/usb.c
> > b/drivers/staging/most/usb/usb.c
> > index 360cb5b7a10b..751e82cf66c5 100644
> > --- a/drivers/staging/most/usb/usb.c
> > +++ b/drivers/staging/most/usb/usb.c
> > @@ -186,32 +186,28 @@ static inline int start_sync_ep(struct
> > usb_device *usb_dev, u16 ep)
> >   */
> >  static unsigned int get_stream_frame_size(struct
> > most_channel_config *cfg)
> >  {
> > - unsigned int frame_size = 0;
> >   unsigned int sub_size = cfg->subbuffer_size;
> >  
> >   if (!sub_size) {
> >   pr_warn("Misconfig: Subbuffer size zero.\n");
> > - return frame_size;
> > + return 0;
> >   }
> >   switch (cfg->data_type) {
> >   case MOST_CH_ISOC:
> > - frame_size = AV_PACKETS_PER_XACT * sub_size;
> > - break;
> > + return AV_PACKETS_PER_XACT * sub_size;
> >   case MOST_CH_SYNC:
> >   if (cfg->packets_per_xact == 0) {
> >   pr_warn("Misconfig: Packets per XACT
> > zero\n");
> > - frame_size = 0;
> > + return 0;
> >   } else if (cfg->packets_per_xact == 0xFF) {
> > - frame_size = (USB_MTU / sub_size) *
> > sub_size;
> > + return (USB_MTU / sub_size) * sub_size;
> >   } else {
> > - frame_size = cfg->packets_per_xact *
> > sub_size;
> > + return cfg->packets_per_xact * sub_size;
> >   }
> > - break;
> >   default:
> >   pr_warn("Query frame size of non-streaming
> > channel\n");
> > - break;
> > + return 0;
> >   }
> > - return frame_size;
> >  }
> Now it just feels like you are doing "busy work" :(
>
> frame_size makes sense here, right?  Why change this code?
>
> Remember, code is written for developers first, the compiler second.
> Reading this with frame_size makes it much more obvious what this
> code
> does when you read it again in 5-10 years.  Why change this, you have
> not made it faster, or smaller at all.
>
> So no, I would not accept this, sorry.

I haven't seen this on time. So please ignore my acknowledge I've sent.
Good to know that you favor readability over compactness.

Sorry for the noise,
Chris

>
> We have so many _real_ things to do in the drivers/staging/ directory
> if
> you are looking for stuff to clean up.  Don't try to micro-optimize
> things that do not matter at the expense of understanding.
>
> thanks,
>
> greg k-h
>