[PATCH] ARM: 8351/1: perf: fix memory leak on return

[PATCH] ARM: 8351/1: perf: fix memory leak on return

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

Recent commit 3b8786ff7a1b31645ae2c26a2ec32dbd42ac1094
("ARM: 8352/1: perf: Fix the pmu node name in warning message")
introduced a memory leak of irqs on the "Don't bother with PPIs"
return path. This was picked up by static analysis by cppcheck:

[arch/arm/kernel/perf_event_cpu.c:315]: (error) Memory leak: irqs

simpele fix is to free irqs when returning.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 arch/arm/kernel/perf_event_cpu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c
index 213919b..9e5b2a5 100644
--- a/arch/arm/kernel/perf_event_cpu.c
+++ b/arch/arm/kernel/perf_event_cpu.c
@@ -311,8 +311,10 @@ static int of_pmu_irq_cfg(struct platform_device *pdev)
 
 	/* Don't bother with PPIs; they're already affine */
 	irq = platform_get_irq(pdev, 0);
-	if (irq >= 0 && irq_is_percpu(irq))
+	if (irq >= 0 && irq_is_percpu(irq)) {
+		kfree(irqs);
 		return 0;
+	}
 
 	for (i = 0; i < pdev->num_resources; ++i) {
 		struct device_node *dn;
-- 
2.1.4

[PATCH] ARM: 8351/1: perf: fix memory leak on return

[Ingo Molnar]

* Colin King <colin.king@canonical.com> wrote:

> From: Colin Ian King <colin.king@canonical.com>
> 
> Recent commit 3b8786ff7a1b31645ae2c26a2ec32dbd42ac1094
> ("ARM: 8352/1: perf: Fix the pmu node name in warning message")
> introduced a memory leak of irqs on the "Don't bother with PPIs"
> return path. This was picked up by static analysis by cppcheck:
> 
> [arch/arm/kernel/perf_event_cpu.c:315]: (error) Memory leak: irqs
> 
> simpele fix is to free irqs when returning.
> 
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  arch/arm/kernel/perf_event_cpu.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c
> index 213919b..9e5b2a5 100644
> --- a/arch/arm/kernel/perf_event_cpu.c
> +++ b/arch/arm/kernel/perf_event_cpu.c
> @@ -311,8 +311,10 @@ static int of_pmu_irq_cfg(struct platform_device *pdev)
>  
>  	/* Don't bother with PPIs; they're already affine */
>  	irq = platform_get_irq(pdev, 0);
> -	if (irq >= 0 && irq_is_percpu(irq))
> +	if (irq >= 0 && irq_is_percpu(irq)) {
> +		kfree(irqs);
>  		return 0;
> +	}
>  
>  	for (i = 0; i < pdev->num_resources; ++i) {
>  		struct device_node *dn;

So returning from the middle of a function isn't very clean.

Also, why do we return 0 in an error case?

Furthermore, this function already has a (partially hidden) error 
cleanup path:

        if (i == pdev->num_resources)
                cpu_pmu->irq_affinity = irqs;
        else
                kfree(irqs);

So this code should use proper goto driven cleanup. That's faster and 
cleaner, and is less likely to result in bugs like the above.

Thanks,

	Ingo

[PATCH] ARM: 8351/1: perf: fix memory leak on return

[Colin Ian King]

On 16/05/15 08:09, Ingo Molnar wrote:
> 
> * Colin King <colin.king@canonical.com> wrote:
> 
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> Recent commit 3b8786ff7a1b31645ae2c26a2ec32dbd42ac1094
>> ("ARM: 8352/1: perf: Fix the pmu node name in warning message")
>> introduced a memory leak of irqs on the "Don't bother with PPIs"
>> return path. This was picked up by static analysis by cppcheck:
>>
>> [arch/arm/kernel/perf_event_cpu.c:315]: (error) Memory leak: irqs
>>
>> simpele fix is to free irqs when returning.
>>
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>> ---
>>  arch/arm/kernel/perf_event_cpu.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c
>> index 213919b..9e5b2a5 100644
>> --- a/arch/arm/kernel/perf_event_cpu.c
>> +++ b/arch/arm/kernel/perf_event_cpu.c
>> @@ -311,8 +311,10 @@ static int of_pmu_irq_cfg(struct platform_device *pdev)
>>  
>>  	/* Don't bother with PPIs; they're already affine */
>>  	irq = platform_get_irq(pdev, 0);
>> -	if (irq >= 0 && irq_is_percpu(irq))
>> +	if (irq >= 0 && irq_is_percpu(irq)) {
>> +		kfree(irqs);
>>  		return 0;
>> +	}
>>  
>>  	for (i = 0; i < pdev->num_resources; ++i) {
>>  		struct device_node *dn;
> 
> So returning from the middle of a function isn't very clean.
> 
> Also, why do we return 0 in an error case?

I believe that's explained in commit
338d9dd3e2aee00a9198e8bf6e7d535d3feeaf32 ("ARM: 8351/1: perf: don't warn
about missing interrupt-affinity property for PPIs"):

"PPIs are affine by nature, so the interrupt-affinity property is not
 used and therefore we shouldn't print a warning in its absence."

> 
> Furthermore, this function already has a (partially hidden) error 
> cleanup path:
> 
>         if (i == pdev->num_resources)
>                 cpu_pmu->irq_affinity = irqs;
>         else
>                 kfree(irqs);
> 
> So this code should use proper goto driven cleanup. That's faster and 
> cleaner, and is less likely to result in bugs like the above.
> 
> Thanks,
> 
> 	Ingo
> 

[PATCH] ARM: 8351/1: perf: fix memory leak on return

[Ingo Molnar]

* Colin Ian King <colin.king@canonical.com> wrote:

> On 16/05/15 08:09, Ingo Molnar wrote:
> > 
> > * Colin King <colin.king@canonical.com> wrote:
> > 
> >> From: Colin Ian King <colin.king@canonical.com>
> >>
> >> Recent commit 3b8786ff7a1b31645ae2c26a2ec32dbd42ac1094
> >> ("ARM: 8352/1: perf: Fix the pmu node name in warning message")
> >> introduced a memory leak of irqs on the "Don't bother with PPIs"
> >> return path. This was picked up by static analysis by cppcheck:
> >>
> >> [arch/arm/kernel/perf_event_cpu.c:315]: (error) Memory leak: irqs
> >>
> >> simpele fix is to free irqs when returning.
> >>
> >> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> >> ---
> >>  arch/arm/kernel/perf_event_cpu.c | 4 +++-
> >>  1 file changed, 3 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c
> >> index 213919b..9e5b2a5 100644
> >> --- a/arch/arm/kernel/perf_event_cpu.c
> >> +++ b/arch/arm/kernel/perf_event_cpu.c
> >> @@ -311,8 +311,10 @@ static int of_pmu_irq_cfg(struct platform_device *pdev)
> >>  
> >>  	/* Don't bother with PPIs; they're already affine */
> >>  	irq = platform_get_irq(pdev, 0);
> >> -	if (irq >= 0 && irq_is_percpu(irq))
> >> +	if (irq >= 0 && irq_is_percpu(irq)) {
> >> +		kfree(irqs);
> >>  		return 0;
> >> +	}
> >>  
> >>  	for (i = 0; i < pdev->num_resources; ++i) {
> >>  		struct device_node *dn;
> > 
> > So returning from the middle of a function isn't very clean.
> > 
> > Also, why do we return 0 in an error case?
> 
> I believe that's explained in commit
> 338d9dd3e2aee00a9198e8bf6e7d535d3feeaf32 ("ARM: 8351/1: perf: don't warn
> about missing interrupt-affinity property for PPIs"):
> 
> "PPIs are affine by nature, so the interrupt-affinity property is not
>  used and therefore we shouldn't print a warning in its absence."

That should probably be mentioned in the fine code as well, to keep 
future generations from wondering.

Thanks,

	Ingo