Re: [PATCH] ARM: OMAP: Fix use of possibly uninitialized irq variable

[Nick Desaulniers]

On Thu, Apr 1, 2021 at 9:12 AM Maciej Falkowski
 wrote:
>
> The current control flow of IRQ number assignment to `irq` variable
> allows a request of IRQ of unspecified value,
> generating a warning under Clang compilation with omap1_defconfig on 
> linux-next:
>
> arch/arm/mach-omap1/pm.c:656:11: warning: variable 'irq' is used 
> uninitialized whenever
> 'if' condition is false [-Wsometimes-uninitialized]
> else if (cpu_is_omap16xx())
>  ^
> ./arch/arm/mach-omap1/include/mach/soc.h:123:30: note: expanded from macro 
> 'cpu_is_omap16xx'
> ^
> arch/arm/mach-omap1/pm.c:658:18: note: uninitialized use occurs here
> if (request_irq(irq, omap_wakeup_interrupt, 0, "peripheral wakeup",
> ^~~
> arch/arm/mach-omap1/pm.c:656:7: note: remove the 'if' if its condition is 
> always true
> else if (cpu_is_omap16xx())
>  ^~
> arch/arm/mach-omap1/pm.c:611:9: note: initialize the variable 'irq' to 
> silence this warning
> int irq;
>^
> = 0
> 1 warning generated.

Ooh, yeah if cpu_is_omap15xx() then irq is unused uninitialized; I
don't see any INT_1610_WAKE_UP_REQ-equlivalent for
INT_15XX_WAKE_UP_REQ.

Ok, LGTM.

Reviewed-by: Nick Desaulniers 

I agree with Nathan on the Fixes tag.

>
> The patch provides a default value to the `irq` variable
> along with a validity check.
>
> Signed-off-by: Maciej Falkowski 
> Link: https://github.com/ClangBuiltLinux/linux/issues/1324
> ---
>  arch/arm/mach-omap1/pm.c | 10 +++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/mach-omap1/pm.c b/arch/arm/mach-omap1/pm.c
> index 2c1e2b32b9b3..a745d64d4699 100644
> --- a/arch/arm/mach-omap1/pm.c
> +++ b/arch/arm/mach-omap1/pm.c
> @@ -655,9 +655,13 @@ static int __init omap_pm_init(void)
> irq = INT_7XX_WAKE_UP_REQ;
> else if (cpu_is_omap16xx())
> irq = INT_1610_WAKE_UP_REQ;
> -   if (request_irq(irq, omap_wakeup_interrupt, 0, "peripheral wakeup",
> -   NULL))
> -   pr_err("Failed to request irq %d (peripheral wakeup)\n", irq);
> +   else
> +   irq = -1;
> +
> +   if (irq >= 0) {
> +   if (request_irq(irq, omap_wakeup_interrupt, 0, "peripheral 
> wakeup", NULL))
> +   pr_err("Failed to request irq %d (peripheral 
> wakeup)\n", irq);
> +   }
>
> /* Program new power ramp-up time
>  * (0 for most boards since we don't lower voltage when in deep sleep)
> --
-- 
Thanks,
~Nick Desaulniers

[PATCH] ARM: OMAP: Fix use of possibly uninitialized irq variable

[Maciej Falkowski]

The current control flow of IRQ number assignment to `irq` variable
allows a request of IRQ of unspecified value,
generating a warning under Clang compilation with omap1_defconfig on linux-next:

arch/arm/mach-omap1/pm.c:656:11: warning: variable 'irq' is used uninitialized 
whenever
'if' condition is false [-Wsometimes-uninitialized]
else if (cpu_is_omap16xx())
 ^
./arch/arm/mach-omap1/include/mach/soc.h:123:30: note: expanded from macro 
'cpu_is_omap16xx'
^
arch/arm/mach-omap1/pm.c:658:18: note: uninitialized use occurs here
if (request_irq(irq, omap_wakeup_interrupt, 0, "peripheral wakeup",
^~~
arch/arm/mach-omap1/pm.c:656:7: note: remove the 'if' if its condition is 
always true
else if (cpu_is_omap16xx())
 ^~
arch/arm/mach-omap1/pm.c:611:9: note: initialize the variable 'irq' to silence 
this warning
int irq;
   ^
= 0
1 warning generated.

The patch provides a default value to the `irq` variable
along with a validity check.

Signed-off-by: Maciej Falkowski 
Link: https://github.com/ClangBuiltLinux/linux/issues/1324
---
 arch/arm/mach-omap1/pm.c | 10 +++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mach-omap1/pm.c b/arch/arm/mach-omap1/pm.c
index 2c1e2b32b9b3..a745d64d4699 100644
--- a/arch/arm/mach-omap1/pm.c
+++ b/arch/arm/mach-omap1/pm.c
@@ -655,9 +655,13 @@ static int __init omap_pm_init(void)
irq = INT_7XX_WAKE_UP_REQ;
else if (cpu_is_omap16xx())
irq = INT_1610_WAKE_UP_REQ;
-   if (request_irq(irq, omap_wakeup_interrupt, 0, "peripheral wakeup",
-   NULL))
-   pr_err("Failed to request irq %d (peripheral wakeup)\n", irq);
+   else
+   irq = -1;
+
+   if (irq >= 0) {
+   if (request_irq(irq, omap_wakeup_interrupt, 0, "peripheral 
wakeup", NULL))
+   pr_err("Failed to request irq %d (peripheral 
wakeup)\n", irq);
+   }
 
/* Program new power ramp-up time
 * (0 for most boards since we don't lower voltage when in deep sleep)
-- 
2.26.3

Re: [PATCH] ARM: OMAP: Fix use of possibly uninitialized irq variable

[Nathan Chancellor]

On Thu, Apr 01, 2021 at 06:11:27PM +0200, Maciej Falkowski wrote:
> The current control flow of IRQ number assignment to `irq` variable
> allows a request of IRQ of unspecified value,
> generating a warning under Clang compilation with omap1_defconfig on 
> linux-next:
> 
> arch/arm/mach-omap1/pm.c:656:11: warning: variable 'irq' is used 
> uninitialized whenever
> 'if' condition is false [-Wsometimes-uninitialized]
> else if (cpu_is_omap16xx())
>  ^
> ./arch/arm/mach-omap1/include/mach/soc.h:123:30: note: expanded from macro 
> 'cpu_is_omap16xx'
> ^
> arch/arm/mach-omap1/pm.c:658:18: note: uninitialized use occurs here
> if (request_irq(irq, omap_wakeup_interrupt, 0, "peripheral wakeup",
> ^~~
> arch/arm/mach-omap1/pm.c:656:7: note: remove the 'if' if its condition is 
> always true
> else if (cpu_is_omap16xx())
>  ^~
> arch/arm/mach-omap1/pm.c:611:9: note: initialize the variable 'irq' to 
> silence this warning
> int irq;
>^
> = 0
> 1 warning generated.
> 
> The patch provides a default value to the `irq` variable
> along with a validity check.
> 

Might be worth a fixes tag:

Fixes: b75ca5217743 ("ARM: OMAP: replace setup_irq() by request_irq()")

> Signed-off-by: Maciej Falkowski 
> Link: https://github.com/ClangBuiltLinux/linux/issues/1324

Reviewed-by: Nathan Chancellor 

> ---
>  arch/arm/mach-omap1/pm.c | 10 +++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/mach-omap1/pm.c b/arch/arm/mach-omap1/pm.c
> index 2c1e2b32b9b3..a745d64d4699 100644
> --- a/arch/arm/mach-omap1/pm.c
> +++ b/arch/arm/mach-omap1/pm.c
> @@ -655,9 +655,13 @@ static int __init omap_pm_init(void)
>   irq = INT_7XX_WAKE_UP_REQ;
>   else if (cpu_is_omap16xx())
>   irq = INT_1610_WAKE_UP_REQ;
> - if (request_irq(irq, omap_wakeup_interrupt, 0, "peripheral wakeup",
> - NULL))
> - pr_err("Failed to request irq %d (peripheral wakeup)\n", irq);
> + else
> + irq = -1;
> +
> + if (irq >= 0) {
> + if (request_irq(irq, omap_wakeup_interrupt, 0, "peripheral 
> wakeup", NULL))
> + pr_err("Failed to request irq %d (peripheral 
> wakeup)\n", irq);
> + }
>  
>   /* Program new power ramp-up time
>* (0 for most boards since we don't lower voltage when in deep sleep)
> -- 
> 2.26.3
>