diff mbox series

[next] Input: Fix fall-through warning for Clang

Message ID 20210607214852.GA65141@embeddedor
State Accepted
Commit f1469e568bf6dcbdff9fd7cd7d2cc9ca9d06efeb
Headers show
Series [next] Input: Fix fall-through warning for Clang | expand

Commit Message

Gustavo A. R. Silva June 7, 2021, 9:48 p.m. UTC
In preparation to enable -Wimplicit-fallthrough for Clang, fix a
warning by explicitly adding a fallthrough; statement.

Link: https://github.com/KSPP/linux/issues/115
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
JFYI: We had thousands of these sorts of warnings and now we are down
      to just 13 in linux-next(20210607). This is one of those last
      remaining warnings. :)

 drivers/input/joystick/sidewinder.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Dmitry Torokhov June 14, 2021, 10:12 p.m. UTC | #1
Hi Joe,

On Mon, Jun 07, 2021 at 03:02:40PM -0700, Joe Perches wrote:
> On Mon, 2021-06-07 at 16:48 -0500, Gustavo A. R. Silva wrote:

> > In preparation to enable -Wimplicit-fallthrough for Clang, fix a

> > warning by explicitly adding a fallthrough; statement.

> []

> > diff --git a/drivers/input/joystick/sidewinder.c b/drivers/input/joystick/sidewinder.c

> []

> > @@ -660,6 +660,7 @@ static int sw_connect(struct gameport *gameport, struct gameport_driver *drv)

> >  					fallthrough;

> >  				case 45:				/* Ambiguous packet length */

> >  					if (j <= 40) {			/* ID length less or eq 40 -> FSP */

> > +					fallthrough;

> >  				case 43:

> >  						sw->type = SW_ID_FSP;

> >  						break;

> 

> Yuck.  Super ugly.  There's no need to play games with indentation.


Yeah, the original code is not pretty :(

> 

> Perhaps the simpler:

> 

> 				case 43:

> 					sw->type = SW_ID_FSP;

> 					break;

> 				case 45:				/* Ambiguous packet length */

> 					if (j <= 40) {			/* ID length less or eq 40 -> FSP */

> 						sw->type = SW_ID_FSP;

> 						break;

> 					}

> 					sw->number++;

> 					fallthrough;

> 

> 


Could you resubmit this version properly formatted?

Thanks.
 
-- 
Dmitry
Gustavo A. R. Silva June 29, 2021, 2:05 p.m. UTC | #2
On Mon, Jun 14, 2021 at 03:12:31PM -0700, Dmitry Torokhov wrote:
> Hi Joe,

> 

> On Mon, Jun 07, 2021 at 03:02:40PM -0700, Joe Perches wrote:

> > On Mon, 2021-06-07 at 16:48 -0500, Gustavo A. R. Silva wrote:

> > > In preparation to enable -Wimplicit-fallthrough for Clang, fix a

> > > warning by explicitly adding a fallthrough; statement.

> > []

> > > diff --git a/drivers/input/joystick/sidewinder.c b/drivers/input/joystick/sidewinder.c

> > []

> > > @@ -660,6 +660,7 @@ static int sw_connect(struct gameport *gameport, struct gameport_driver *drv)

> > >  					fallthrough;

> > >  				case 45:				/* Ambiguous packet length */

> > >  					if (j <= 40) {			/* ID length less or eq 40 -> FSP */

> > > +					fallthrough;

> > >  				case 43:

> > >  						sw->type = SW_ID_FSP;

> > >  						break;

> > 

> > Yuck.  Super ugly.  There's no need to play games with indentation.

> 

> Yeah, the original code is not pretty :(


Isn't this a Duff device for performance[1]?

In which case it might be better not to modify it and just go
with the fallthrough marking?

Another similar case can be found at
drivers/scsi/aic94xx/aic94xx_sds.c:714:

 714 static void *asd_find_ll_by_id(void * const start, const u8 id0, const u8 id1)
 715 {
 716         struct asd_ll_el *el = start;
 717
 718         do {
 719                 switch (id1) {
 720                 default:
 721                         if (el->id1 == id1)
 722                 case 0xFF:
 723                                 if (el->id0 == id0)
 724                                         return el;
 725                 }
 726                 el = start + le16_to_cpu(el->next);
 727         } while (el != start);
 728
 729         return NULL;
 730 }

--
Gustavo

[1] https://www.drdobbs.com/a-reusable-duff-device/184406208

> 

> > 

> > Perhaps the simpler:

> > 

> > 				case 43:

> > 					sw->type = SW_ID_FSP;

> > 					break;

> > 				case 45:				/* Ambiguous packet length */

> > 					if (j <= 40) {			/* ID length less or eq 40 -> FSP */

> > 						sw->type = SW_ID_FSP;

> > 						break;

> > 					}

> > 					sw->number++;

> > 					fallthrough;

> > 

> > 

> 

> Could you resubmit this version properly formatted?

> 

> Thanks.

>  

> -- 

> Dmitry
diff mbox series

Patch

diff --git a/drivers/input/joystick/sidewinder.c b/drivers/input/joystick/sidewinder.c
index fac91ea14f17..8e9672deb1eb 100644
--- a/drivers/input/joystick/sidewinder.c
+++ b/drivers/input/joystick/sidewinder.c
@@ -660,6 +660,7 @@  static int sw_connect(struct gameport *gameport, struct gameport_driver *drv)
 					fallthrough;
 				case 45:				/* Ambiguous packet length */
 					if (j <= 40) {			/* ID length less or eq 40 -> FSP */
+					fallthrough;
 				case 43:
 						sw->type = SW_ID_FSP;
 						break;