[PATCH] drivers: staging: comedi: Fixed side effects from macro definition.

[PATCH] drivers: staging: comedi: Fixed side effects from macro definition.

[chakravarthikulkarni]

Warning found by checkpatch.pl script.

Signed-off-by: chakravarthikulkarni <chakravarthikulkarni2021@gmail.com>
---
 drivers/staging/comedi/comedi.h | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/comedi/comedi.h b/drivers/staging/comedi/comedi.h
index b5d00a006dbb..b2af6a88d389 100644
--- a/drivers/staging/comedi/comedi.h
+++ b/drivers/staging/comedi/comedi.h
@@ -1103,9 +1103,12 @@ enum ni_common_signal_names {
 
 /* *** END GLOBALLY-NAMED NI TERMINALS/SIGNALS *** */
 
-#define NI_USUAL_PFI_SELECT(x)	(((x) < 10) ? (0x1 + (x)) : (0xb + (x)))
-#define NI_USUAL_RTSI_SELECT(x)	(((x) < 7) ? (0xb + (x)) : 0x1b)
-
+#define NI_USUAL_PFI_SELECT(x) \
+	({ typeof(x) _x = x; \
+	 (((_x) < 10) ? (0x1 + (_x)) : (0xb + (_x))); })
+#define NI_USUAL_RTSI_SELECT(x)	\
+	({ typeof(x) _x = x; \
+	 (((_x) < 7) ? (0xb + (_x)) : 0x1b); })
 /*
  * mode bits for NI general-purpose counters, set with
  * INSN_CONFIG_SET_COUNTER_MODE
-- 
2.17.1

Re: [PATCH] drivers: staging: comedi: Fixed side effects from macro definition.

[Ian Abbott]

On 17/02/2021 14:20, chakravarthikulkarni wrote:
> Warning found by checkpatch.pl script.
> 
> Signed-off-by: chakravarthikulkarni <chakravarthikulkarni2021@gmail.com>
> ---
>   drivers/staging/comedi/comedi.h | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/comedi/comedi.h b/drivers/staging/comedi/comedi.h
> index b5d00a006dbb..b2af6a88d389 100644
> --- a/drivers/staging/comedi/comedi.h
> +++ b/drivers/staging/comedi/comedi.h
> @@ -1103,9 +1103,12 @@ enum ni_common_signal_names {
>   
>   /* *** END GLOBALLY-NAMED NI TERMINALS/SIGNALS *** */
>   
> -#define NI_USUAL_PFI_SELECT(x)	(((x) < 10) ? (0x1 + (x)) : (0xb + (x)))
> -#define NI_USUAL_RTSI_SELECT(x)	(((x) < 7) ? (0xb + (x)) : 0x1b)
> -
> +#define NI_USUAL_PFI_SELECT(x) \
> +	({ typeof(x) _x = x; \
> +	 (((_x) < 10) ? (0x1 + (_x)) : (0xb + (_x))); })
> +#define NI_USUAL_RTSI_SELECT(x)	\
> +	({ typeof(x) _x = x; \
> +	 (((_x) < 7) ? (0xb + (_x)) : 0x1b); })
>   /*
>    * mode bits for NI general-purpose counters, set with
>    * INSN_CONFIG_SET_COUNTER_MODE
> 

I'd rather not do that because this is intended to be a userspace 
header.  This change adds GCC extensions and prohibits the use of the 
macros in constant expressions.

-- 
-=( Ian Abbott <abbotti@mev.co.uk> || MEV Ltd. is a company  )=-
-=( registered in England & Wales.  Regd. number: 02862268.  )=-
-=( Regd. addr.: S11 & 12 Building 67, Europa Business Park, )=-
-=( Bird Hall Lane, STOCKPORT, SK3 0XA, UK. || www.mev.co.uk )=-

Re: [PATCH] drivers: staging: comedi: Fixed side effects from macro definition.

[Greg Kroah-Hartman]

A: http://en.wikipedia.org/wiki/Top_post
Q: Were do I find info about this thing called top-posting?
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

A: No.
Q: Should I include quotations after my reply?

http://daringfireball.net/2007/07/on_top

On Wed, Feb 24, 2021 at 12:47:26PM +0530, chakravarthi Kulkarni wrote:
> Hi,
> 
> I tested it will unit test cases it looks fine.
> int x = 10;
> NI_USUAL_PFI_SELECT(x++)
> 
> will not have side effects as it is taken care using local variable in
> macro.

You ignored what Ian said about why this change was not ok :(

It's long deleted from my review queue, sorry.

greg k-h