[PATCH] selftests/rtc:Fix a resource leak

[PATCH] selftests/rtc:Fix a resource leak

[Zhu Jun]

The opened file should be closed before exit, otherwise resource leak
will occur that this problem was discovered by reading code

Signed-off-by: Zhu Jun <zhujun2@cmss.chinamobile.com>
---
 tools/testing/selftests/rtc/setdate.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/rtc/setdate.c b/tools/testing/selftests/rtc/setdate.c
index b303890b3de2..17a00affb0ec 100644
--- a/tools/testing/selftests/rtc/setdate.c
+++ b/tools/testing/selftests/rtc/setdate.c
@@ -65,6 +65,7 @@ int main(int argc, char **argv)
 	retval = ioctl(fd, RTC_RD_TIME, &current);
 	if (retval == -1) {
 		perror("RTC_RD_TIME ioctl");
+		close(fd);
 		exit(errno);
 	}
 
-- 
2.17.1

Re: [PATCH] selftests/rtc:Fix a resource leak

[Alexandre Belloni]

On 09/07/2024 23:07:43-0700, Zhu Jun wrote:
> The opened file should be closed before exit, otherwise resource leak
> will occur that this problem was discovered by reading code

Can you elaborate on the leak? All the fds are getting closed on exit.

> 
> Signed-off-by: Zhu Jun <zhujun2@cmss.chinamobile.com>
> ---
>  tools/testing/selftests/rtc/setdate.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tools/testing/selftests/rtc/setdate.c b/tools/testing/selftests/rtc/setdate.c
> index b303890b3de2..17a00affb0ec 100644
> --- a/tools/testing/selftests/rtc/setdate.c
> +++ b/tools/testing/selftests/rtc/setdate.c
> @@ -65,6 +65,7 @@ int main(int argc, char **argv)
>  	retval = ioctl(fd, RTC_RD_TIME, &current);
>  	if (retval == -1) {
>  		perror("RTC_RD_TIME ioctl");
> +		close(fd);
>  		exit(errno);
>  	}
>  
> -- 
> 2.17.1
> 
> 
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

[PATCH v2] selftests/rtc:Fix a resource leak

[Zhu Jun]

The opened file should be closed before exit, otherwise resource leak
will occur that this problem was discovered by code reading

Signed-off-by: Zhu Jun <zhujun2@cmss.chinamobile.com>
---
From a good programming practice perspective, especially in more complex programs, 
explicitly freeing allocated memory is a good habit!


 tools/testing/selftests/rtc/setdate.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/rtc/setdate.c b/tools/testing/selftests/rtc/setdate.c
index b303890b3de2..17a00affb0ec 100644
--- a/tools/testing/selftests/rtc/setdate.c
+++ b/tools/testing/selftests/rtc/setdate.c
@@ -65,6 +65,7 @@ int main(int argc, char **argv)
 	retval = ioctl(fd, RTC_RD_TIME, &current);
 	if (retval == -1) {
 		perror("RTC_RD_TIME ioctl");
+		close(fd);
 		exit(errno);
 	}
 
-- 
2.17.1

Re: [PATCH v2] selftests/rtc:Fix a resource leak

[Alexandre Belloni]

On 10/07/2024 00:43:09-0700, Zhu Jun wrote:
> The opened file should be closed before exit, otherwise resource leak
> will occur that this problem was discovered by code reading

The question is still why should it be closed before exit as it will be
closed on exit?

> 
> Signed-off-by: Zhu Jun <zhujun2@cmss.chinamobile.com>
> ---
> From a good programming practice perspective, especially in more complex programs, 
> explicitly freeing allocated memory is a good habit!
> 
> 
>  tools/testing/selftests/rtc/setdate.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tools/testing/selftests/rtc/setdate.c b/tools/testing/selftests/rtc/setdate.c
> index b303890b3de2..17a00affb0ec 100644
> --- a/tools/testing/selftests/rtc/setdate.c
> +++ b/tools/testing/selftests/rtc/setdate.c
> @@ -65,6 +65,7 @@ int main(int argc, char **argv)
>  	retval = ioctl(fd, RTC_RD_TIME, &current);
>  	if (retval == -1) {
>  		perror("RTC_RD_TIME ioctl");
> +		close(fd);
>  		exit(errno);
>  	}
>  
> -- 
> 2.17.1
> 
> 
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v2] selftests/rtc:Fix a resource leak

[Shuah Khan]

On 7/10/24 01:55, Alexandre Belloni wrote:
> On 10/07/2024 00:43:09-0700, Zhu Jun wrote:
>> The opened file should be closed before exit, otherwise resource leak
>> will occur that this problem was discovered by code reading
> 
> The question is still why should it be closed before exit as it will be
> closed on exit?
> 

Zhu Jun,

+1 on this. I have responded to your other patches that do the same
in other tests. There is no need to make such changes.

thanks,
-- Shuah

Re: [PATCH v2] selftests/rtc:Fix a resource leak

[John Hubbard]

On 7/10/24 9:00 AM, Shuah Khan wrote:
> On 7/10/24 01:55, Alexandre Belloni wrote:
>> On 10/07/2024 00:43:09-0700, Zhu Jun wrote:
>>> The opened file should be closed before exit, otherwise resource leak
>>> will occur that this problem was discovered by code reading
>>
>> The question is still why should it be closed before exit as it will be
>> closed on exit?
>>
> 
> Zhu Jun,
> 
> +1 on this. I have responded to your other patches that do the same
> in other tests. There is no need to make such changes.
> 
> thanks,
> -- Shuah
> 

Yes. What Shuah and Alexandre said. And the same reasoning also applies
to memory buffers: they are also released by the kernel at program exit.

This blind adherence to "good programming practices" is not helpful here,
because it turns out that selftests are small, short-running, and simple.
These are all desirable properties, because remember, there are no
tests to verify the selftests, so we rely on keeping them simple and
very easy to quickly read and understand.

"Good programming practices" is not a "one approach to all programs"
thing.

So adding line count to free something a few lines before program exit,
for tiny programs, is actually counter productive in this environment.

Zhu, if you're going to keep working on selftests, I think you would
really benefit from some of the literature that goes into the design
philosophy for unit tests. Google has the best (and most recent) work
IMHO [1], but there are others of course.

[1] Software Engineering at Google (Apr 7, 2020), by Titus Winters

thanks,
-- 
John Hubbard
NVIDIA