* [PATCH] staging: gdm724x: Fix Duplication of Side Effects
@ 2022-03-31 10:18 Alaa Mohamed
2022-03-31 10:27 ` Dan Carpenter
` (2 more replies)
0 siblings, 3 replies; 7+ messages in thread
From: Alaa Mohamed @ 2022-03-31 10:18 UTC (permalink / raw)
To: outreachy; +Cc: gregkh, linux-staging, linux-kernel, eng.alaamohamedsoliman.am
Fix Duplication of Side Effects for GDM_TTY_READY(gdm) macro
reported by checkpatch
"CHECK: Macro argument reuse 'gdm' - possible side-effects?"
Signed-off-by: Alaa Mohamed <eng.alaamohamedsoliman.am@gmail.com>
---
drivers/staging/gdm724x/gdm_tty.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/staging/gdm724x/gdm_tty.c b/drivers/staging/gdm724x/gdm_tty.c
index 04df6f9f5403..6f0274470e69 100644
--- a/drivers/staging/gdm724x/gdm_tty.c
+++ b/drivers/staging/gdm724x/gdm_tty.c
@@ -27,7 +27,9 @@
#define MUX_TX_MAX_SIZE 2048
-#define GDM_TTY_READY(gdm) (gdm && gdm->tty_dev && gdm->port.count)
+#define GDM_TTY_READY(_gdm) \
+ ({ typeof(_gdm) (gdm) = (_gdm); \
+ (gdm && gdm->tty_dev && gdm->port.count); })
static struct tty_driver *gdm_driver[TTY_MAX_COUNT];
static struct gdm *gdm_table[TTY_MAX_COUNT][GDM_TTY_MINOR];
--
2.35.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] staging: gdm724x: Fix Duplication of Side Effects
2022-03-31 10:18 [PATCH] staging: gdm724x: Fix Duplication of Side Effects Alaa Mohamed
@ 2022-03-31 10:27 ` Dan Carpenter
2022-03-31 10:29 ` David Laight
2022-03-31 11:33 ` Greg KH
2 siblings, 0 replies; 7+ messages in thread
From: Dan Carpenter @ 2022-03-31 10:27 UTC (permalink / raw)
To: Alaa Mohamed; +Cc: outreachy, gregkh, linux-staging, linux-kernel
On Thu, Mar 31, 2022 at 12:18:49PM +0200, Alaa Mohamed wrote:
> Fix Duplication of Side Effects for GDM_TTY_READY(gdm) macro
> reported by checkpatch
> "CHECK: Macro argument reuse 'gdm' - possible side-effects?"
>
> Signed-off-by: Alaa Mohamed <eng.alaamohamedsoliman.am@gmail.com>
> ---
> drivers/staging/gdm724x/gdm_tty.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/staging/gdm724x/gdm_tty.c b/drivers/staging/gdm724x/gdm_tty.c
> index 04df6f9f5403..6f0274470e69 100644
> --- a/drivers/staging/gdm724x/gdm_tty.c
> +++ b/drivers/staging/gdm724x/gdm_tty.c
> @@ -27,7 +27,9 @@
>
> #define MUX_TX_MAX_SIZE 2048
>
> -#define GDM_TTY_READY(gdm) (gdm && gdm->tty_dev && gdm->port.count)
> +#define GDM_TTY_READY(_gdm) \
> + ({ typeof(_gdm) (gdm) = (_gdm); \
> + (gdm && gdm->tty_dev && gdm->port.count); })
The new macro is uglier. This is not a real bug and there is very
little chance it will become a bug in the future. So it's fine to leave
it as is.
Or another option would be to make it an inline function.
regards,
dan carpenter
^ permalink raw reply [flat|nested] 7+ messages in thread
* RE: [PATCH] staging: gdm724x: Fix Duplication of Side Effects
2022-03-31 10:18 [PATCH] staging: gdm724x: Fix Duplication of Side Effects Alaa Mohamed
2022-03-31 10:27 ` Dan Carpenter
@ 2022-03-31 10:29 ` David Laight
2022-03-31 10:40 ` Dan Carpenter
2022-03-31 11:33 ` Greg KH
2 siblings, 1 reply; 7+ messages in thread
From: David Laight @ 2022-03-31 10:29 UTC (permalink / raw)
To: 'Alaa Mohamed', outreachy; +Cc: gregkh, linux-staging, linux-kernel
From: Alaa Mohamed
> Sent: 31 March 2022 11:19
>
> Fix Duplication of Side Effects for GDM_TTY_READY(gdm) macro
> reported by checkpatch
> "CHECK: Macro argument reuse 'gdm' - possible side-effects?"
>
> Signed-off-by: Alaa Mohamed <eng.alaamohamedsoliman.am@gmail.com>
> ---
> drivers/staging/gdm724x/gdm_tty.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/staging/gdm724x/gdm_tty.c b/drivers/staging/gdm724x/gdm_tty.c
> index 04df6f9f5403..6f0274470e69 100644
> --- a/drivers/staging/gdm724x/gdm_tty.c
> +++ b/drivers/staging/gdm724x/gdm_tty.c
> @@ -27,7 +27,9 @@
>
> #define MUX_TX_MAX_SIZE 2048
>
> -#define GDM_TTY_READY(gdm) (gdm && gdm->tty_dev && gdm->port.count)
> +#define GDM_TTY_READY(_gdm) \
> + ({ typeof(_gdm) (gdm) = (_gdm); \
> + (gdm && gdm->tty_dev && gdm->port.count); })
Did you test this?
see https://godbolt.org/z/cazPrrzPv
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] staging: gdm724x: Fix Duplication of Side Effects
2022-03-31 10:29 ` David Laight
@ 2022-03-31 10:40 ` Dan Carpenter
2022-03-31 10:49 ` David Laight
0 siblings, 1 reply; 7+ messages in thread
From: Dan Carpenter @ 2022-03-31 10:40 UTC (permalink / raw)
To: David Laight
Cc: 'Alaa Mohamed', outreachy, gregkh, linux-staging, linux-kernel
On Thu, Mar 31, 2022 at 10:29:04AM +0000, David Laight wrote:
> From: Alaa Mohamed
> > Sent: 31 March 2022 11:19
> >
> > Fix Duplication of Side Effects for GDM_TTY_READY(gdm) macro
> > reported by checkpatch
> > "CHECK: Macro argument reuse 'gdm' - possible side-effects?"
> >
> > Signed-off-by: Alaa Mohamed <eng.alaamohamedsoliman.am@gmail.com>
> > ---
> > drivers/staging/gdm724x/gdm_tty.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/staging/gdm724x/gdm_tty.c b/drivers/staging/gdm724x/gdm_tty.c
> > index 04df6f9f5403..6f0274470e69 100644
> > --- a/drivers/staging/gdm724x/gdm_tty.c
> > +++ b/drivers/staging/gdm724x/gdm_tty.c
> > @@ -27,7 +27,9 @@
> >
> > #define MUX_TX_MAX_SIZE 2048
> >
> > -#define GDM_TTY_READY(gdm) (gdm && gdm->tty_dev && gdm->port.count)
> > +#define GDM_TTY_READY(_gdm) \
> > + ({ typeof(_gdm) (gdm) = (_gdm); \
> > + (gdm && gdm->tty_dev && gdm->port.count); })
>
> Did you test this?
>
> see https://godbolt.org/z/cazPrrzPv
>
I don't understand the link. The patch should work as far as I can see.
regards,
dan carpenter
^ permalink raw reply [flat|nested] 7+ messages in thread
* RE: [PATCH] staging: gdm724x: Fix Duplication of Side Effects
2022-03-31 10:40 ` Dan Carpenter
@ 2022-03-31 10:49 ` David Laight
2022-03-31 11:00 ` Dan Carpenter
0 siblings, 1 reply; 7+ messages in thread
From: David Laight @ 2022-03-31 10:49 UTC (permalink / raw)
To: 'Dan Carpenter'
Cc: 'Alaa Mohamed', outreachy, gregkh, linux-staging, linux-kernel
From: Dan Carpenter
> Sent: 31 March 2022 11:40
>
> On Thu, Mar 31, 2022 at 10:29:04AM +0000, David Laight wrote:
> > From: Alaa Mohamed
> > > Sent: 31 March 2022 11:19
> > >
> > > Fix Duplication of Side Effects for GDM_TTY_READY(gdm) macro
> > > reported by checkpatch
> > > "CHECK: Macro argument reuse 'gdm' - possible side-effects?"
> > >
> > > Signed-off-by: Alaa Mohamed <eng.alaamohamedsoliman.am@gmail.com>
> > > ---
> > > drivers/staging/gdm724x/gdm_tty.c | 4 +++-
> > > 1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/staging/gdm724x/gdm_tty.c b/drivers/staging/gdm724x/gdm_tty.c
> > > index 04df6f9f5403..6f0274470e69 100644
> > > --- a/drivers/staging/gdm724x/gdm_tty.c
> > > +++ b/drivers/staging/gdm724x/gdm_tty.c
> > > @@ -27,7 +27,9 @@
> > >
> > > #define MUX_TX_MAX_SIZE 2048
> > >
> > > -#define GDM_TTY_READY(gdm) (gdm && gdm->tty_dev && gdm->port.count)
> > > +#define GDM_TTY_READY(_gdm) \
> > > + ({ typeof(_gdm) (gdm) = (_gdm); \
> > > + (gdm && gdm->tty_dev && gdm->port.count); })
> >
> > Did you test this?
> >
> > see https://godbolt.org/z/cazPrrzPv
> >
>
> I don't understand the link. The patch should work as far as I can see.
If you call GDM_TTY_READY(gdm) the first line ends up as:
struct xxx *gdm = gdm;
which shadows the parameter.
There's probably a warning about an uninitialised variable as well.
The 'gdm' and '_gdm' would need swapping over.
But, as you said, just:
#define GDM_TTY_READY(gdm) ((gdm) && (gdm)->tty_dev && (gdm)->port.count)
is fine - I'd add the () but not worry about multiple evaluation.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] staging: gdm724x: Fix Duplication of Side Effects
2022-03-31 10:49 ` David Laight
@ 2022-03-31 11:00 ` Dan Carpenter
0 siblings, 0 replies; 7+ messages in thread
From: Dan Carpenter @ 2022-03-31 11:00 UTC (permalink / raw)
To: David Laight
Cc: 'Alaa Mohamed', outreachy, gregkh, linux-staging, linux-kernel
On Thu, Mar 31, 2022 at 10:49:24AM +0000, David Laight wrote:
> From: Dan Carpenter
> > Sent: 31 March 2022 11:40
> >
> > On Thu, Mar 31, 2022 at 10:29:04AM +0000, David Laight wrote:
> > > From: Alaa Mohamed
> > > > Sent: 31 March 2022 11:19
> > > >
> > > > Fix Duplication of Side Effects for GDM_TTY_READY(gdm) macro
> > > > reported by checkpatch
> > > > "CHECK: Macro argument reuse 'gdm' - possible side-effects?"
> > > >
> > > > Signed-off-by: Alaa Mohamed <eng.alaamohamedsoliman.am@gmail.com>
> > > > ---
> > > > drivers/staging/gdm724x/gdm_tty.c | 4 +++-
> > > > 1 file changed, 3 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/staging/gdm724x/gdm_tty.c b/drivers/staging/gdm724x/gdm_tty.c
> > > > index 04df6f9f5403..6f0274470e69 100644
> > > > --- a/drivers/staging/gdm724x/gdm_tty.c
> > > > +++ b/drivers/staging/gdm724x/gdm_tty.c
> > > > @@ -27,7 +27,9 @@
> > > >
> > > > #define MUX_TX_MAX_SIZE 2048
> > > >
> > > > -#define GDM_TTY_READY(gdm) (gdm && gdm->tty_dev && gdm->port.count)
> > > > +#define GDM_TTY_READY(_gdm) \
> > > > + ({ typeof(_gdm) (gdm) = (_gdm); \
> > > > + (gdm && gdm->tty_dev && gdm->port.count); })
> > >
> > > Did you test this?
> > >
> > > see https://godbolt.org/z/cazPrrzPv
> > >
> >
> > I don't understand the link. The patch should work as far as I can see.
>
> If you call GDM_TTY_READY(gdm) the first line ends up as:
> struct xxx *gdm = gdm;
> which shadows the parameter.
> There's probably a warning about an uninitialised variable as well.
Oh yeah. You're right. But you won't get any variable uninitialized
warnings because int foo = foo; was the traditional way to silence GCC's
uninitialized variable warnings.
Smatch copied the GCC code. There are some static checkers which might
complain. Sparse used to have a warning about shadow variables but it
didn't trigger on this code. Not sure why.
regards,
dan carpenter
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] staging: gdm724x: Fix Duplication of Side Effects
2022-03-31 10:18 [PATCH] staging: gdm724x: Fix Duplication of Side Effects Alaa Mohamed
2022-03-31 10:27 ` Dan Carpenter
2022-03-31 10:29 ` David Laight
@ 2022-03-31 11:33 ` Greg KH
2 siblings, 0 replies; 7+ messages in thread
From: Greg KH @ 2022-03-31 11:33 UTC (permalink / raw)
To: Alaa Mohamed; +Cc: outreachy, linux-staging, linux-kernel
On Thu, Mar 31, 2022 at 12:18:49PM +0200, Alaa Mohamed wrote:
> Fix Duplication of Side Effects for GDM_TTY_READY(gdm) macro
> reported by checkpatch
> "CHECK: Macro argument reuse 'gdm' - possible side-effects?"
There are no such side-effects here, sorry. Please always evaluate the
code to see what it does, checkpatch sometimes gets it wrong.
thanks,
greg k-h
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-03-31 11:33 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2022-03-31 10:18 [PATCH] staging: gdm724x: Fix Duplication of Side Effects Alaa Mohamed
2022-03-31 10:27 ` Dan Carpenter
2022-03-31 10:29 ` David Laight
2022-03-31 10:40 ` Dan Carpenter
2022-03-31 10:49 ` David Laight
2022-03-31 11:00 ` Dan Carpenter
2022-03-31 11:33 ` Greg KH
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