* [PATCH v2] staging: comedi: rewrite macro function with GNU extension typeof @ 2019-11-04 16:33 Jules Irenge 2019-11-04 16:46 ` Greg KH 2019-11-04 17:03 ` Ian Abbott 0 siblings, 2 replies; 6+ messages in thread From: Jules Irenge @ 2019-11-04 16:33 UTC (permalink / raw) To: outreachy-kernel; +Cc: devel, Jules Irenge, gregkh, linux-kernel, abbotti Rewrite macro function with the GNU extension typeof to remove a possible side-effects of MACRO argument reuse "x". - Problem could rise if arguments have different types and different use though. Signed-off-by: Jules Irenge <jbi.octave@gmail.com> --- v1 - had no full commit log message, with changes not intended to be in the patch v2 - remove some changes not intended to be in this driver include note of a potential problem drivers/staging/comedi/comedi.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/staging/comedi/comedi.h b/drivers/staging/comedi/comedi.h index 09a940066c0e..a57691a2e8d8 100644 --- a/drivers/staging/comedi/comedi.h +++ b/drivers/staging/comedi/comedi.h @@ -1103,8 +1103,10 @@ 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 -- 2.23.0 _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2] staging: comedi: rewrite macro function with GNU extension typeof 2019-11-04 16:33 [PATCH v2] staging: comedi: rewrite macro function with GNU extension typeof Jules Irenge @ 2019-11-04 16:46 ` Greg KH 2019-11-05 11:07 ` Jules Irenge 2019-11-04 17:03 ` Ian Abbott 1 sibling, 1 reply; 6+ messages in thread From: Greg KH @ 2019-11-04 16:46 UTC (permalink / raw) To: Jules Irenge; +Cc: devel, outreachy-kernel, abbotti, linux-kernel On Mon, Nov 04, 2019 at 04:33:31PM +0000, Jules Irenge wrote: > Rewrite macro function with the GNU extension typeof > to remove a possible side-effects of MACRO argument reuse "x". > - Problem could rise if arguments have different types > and different use though. You can not just get away with a potential problem by documenting it :) You might have just broken this. Why are you trying to "fix" something that is not broken? What is wrong with the code as-is? thanks, greg k-h _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] staging: comedi: rewrite macro function with GNU extension typeof 2019-11-04 16:46 ` Greg KH @ 2019-11-05 11:07 ` Jules Irenge 0 siblings, 0 replies; 6+ messages in thread From: Jules Irenge @ 2019-11-05 11:07 UTC (permalink / raw) To: Greg KH; +Cc: devel, outreachy-kernel, Jules Irenge, abbotti, linux-kernel On Mon, 4 Nov 2019, Greg KH wrote: > On Mon, Nov 04, 2019 at 04:33:31PM +0000, Jules Irenge wrote: > > Rewrite macro function with the GNU extension typeof > > to remove a possible side-effects of MACRO argument reuse "x". > > - Problem could rise if arguments have different types > > and different use though. > > You can not just get away with a potential problem by documenting it :) > > You might have just broken this. Why are you trying to "fix" something > that is not broken? > > What is wrong with the code as-is? > > thanks, > > greg k-h > Again I made a lot of mistake. I will be more carefull. Thanks for the feedback _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] staging: comedi: rewrite macro function with GNU extension typeof 2019-11-04 16:33 [PATCH v2] staging: comedi: rewrite macro function with GNU extension typeof Jules Irenge 2019-11-04 16:46 ` Greg KH @ 2019-11-04 17:03 ` Ian Abbott 2019-11-04 20:46 ` Greg KH 2019-11-05 11:00 ` Jules Irenge 1 sibling, 2 replies; 6+ messages in thread From: Ian Abbott @ 2019-11-04 17:03 UTC (permalink / raw) To: Jules Irenge, outreachy-kernel; +Cc: devel, gregkh, linux-kernel On 04/11/2019 16:33, Jules Irenge wrote: > Rewrite macro function with the GNU extension typeof > to remove a possible side-effects of MACRO argument reuse "x". > - Problem could rise if arguments have different types > and different use though. > > Signed-off-by: Jules Irenge <jbi.octave@gmail.com> > --- > v1 - had no full commit log message, with changes not intended to be in the patch > v2 - remove some changes not intended to be in this driver > include note of a potential problem > drivers/staging/comedi/comedi.h | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/staging/comedi/comedi.h b/drivers/staging/comedi/comedi.h > index 09a940066c0e..a57691a2e8d8 100644 > --- a/drivers/staging/comedi/comedi.h > +++ b/drivers/staging/comedi/comedi.h > @@ -1103,8 +1103,10 @@ 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 > I wasn't sure about this the first time around due to the use of GNU extensions in uapi header files, but I see there are a few, rare instances of this GNU extension elsewhere in other uapi headers (mainly in netfilter stuff), so I guess it's OK. However, it does mean that user code that uses these macros will no longer compile unless GNU extensions are enabled. Does anyone know any "best practices" regarding use of GNU extensions in user header files under Linux? -- -=( Ian Abbott <abbotti@mev.co.uk> || Web: www.mev.co.uk )=- -=( MEV Ltd. is a company registered in England & Wales. )=- -=( Registered number: 02862268. Registered address: )=- -=( 15 West Park Road, Bramhall, STOCKPORT, SK7 3JZ, UK. )=- _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] staging: comedi: rewrite macro function with GNU extension typeof 2019-11-04 17:03 ` Ian Abbott @ 2019-11-04 20:46 ` Greg KH 2019-11-05 11:00 ` Jules Irenge 1 sibling, 0 replies; 6+ messages in thread From: Greg KH @ 2019-11-04 20:46 UTC (permalink / raw) To: Ian Abbott; +Cc: devel, outreachy-kernel, Jules Irenge, linux-kernel On Mon, Nov 04, 2019 at 05:03:04PM +0000, Ian Abbott wrote: > On 04/11/2019 16:33, Jules Irenge wrote: > > Rewrite macro function with the GNU extension typeof > > to remove a possible side-effects of MACRO argument reuse "x". > > - Problem could rise if arguments have different types > > and different use though. > > > > Signed-off-by: Jules Irenge <jbi.octave@gmail.com> > > --- > > v1 - had no full commit log message, with changes not intended to be in the patch > > v2 - remove some changes not intended to be in this driver > > include note of a potential problem > > drivers/staging/comedi/comedi.h | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/staging/comedi/comedi.h b/drivers/staging/comedi/comedi.h > > index 09a940066c0e..a57691a2e8d8 100644 > > --- a/drivers/staging/comedi/comedi.h > > +++ b/drivers/staging/comedi/comedi.h > > @@ -1103,8 +1103,10 @@ 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 > > > > I wasn't sure about this the first time around due to the use of GNU > extensions in uapi header files, but I see there are a few, rare instances > of this GNU extension elsewhere in other uapi headers (mainly in netfilter > stuff), so I guess it's OK. However, it does mean that user code that uses > these macros will no longer compile unless GNU extensions are enabled. > > Does anyone know any "best practices" regarding use of GNU extensions in > user header files under Linux? We try to never do it if at all possible :) thanks, greg k-h _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] staging: comedi: rewrite macro function with GNU extension typeof 2019-11-04 17:03 ` Ian Abbott 2019-11-04 20:46 ` Greg KH @ 2019-11-05 11:00 ` Jules Irenge 1 sibling, 0 replies; 6+ messages in thread From: Jules Irenge @ 2019-11-05 11:00 UTC (permalink / raw) To: Ian Abbott; +Cc: devel, Jules Irenge, gregkh, linux-kernel, outreachy-kernel On Mon, 4 Nov 2019, Ian Abbott wrote: > On 04/11/2019 16:33, Jules Irenge wrote: > > Rewrite macro function with the GNU extension typeof > > to remove a possible side-effects of MACRO argument reuse "x". > > - Problem could rise if arguments have different types > > and different use though. > > > > Signed-off-by: Jules Irenge <jbi.octave@gmail.com> > > --- > > v1 - had no full commit log message, with changes not intended to be in the > > patch > > v2 - remove some changes not intended to be in this driver > > include note of a potential problem > > drivers/staging/comedi/comedi.h | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/staging/comedi/comedi.h > > b/drivers/staging/comedi/comedi.h > > index 09a940066c0e..a57691a2e8d8 100644 > > --- a/drivers/staging/comedi/comedi.h > > +++ b/drivers/staging/comedi/comedi.h > > @@ -1103,8 +1103,10 @@ 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 > > > > I wasn't sure about this the first time around due to the use of GNU > extensions in uapi header files, but I see there are a few, rare instances of > this GNU extension elsewhere in other uapi headers (mainly in netfilter > stuff), so I guess it's OK. However, it does mean that user code that uses > these macros will no longer compile unless GNU extensions are enabled. > > Does anyone know any "best practices" regarding use of GNU extensions in user > header files under Linux? > > -- > -=( Ian Abbott <abbotti@mev.co.uk> || Web: www.mev.co.uk )=- > -=( MEV Ltd. is a company registered in England & Wales. )=- > -=( Registered number: 02862268. Registered address: )=- > -=( 15 West Park Road, Bramhall, STOCKPORT, SK7 3JZ, UK. )=- > > Apology, I misinterpreted the comments and send a second version without thinking much. Please discard it unless you wish to try out. Any way thanks for the feedback, I really appreciate I find it educative. Kind regards, Jules _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
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