Re: [PATCH] selftests/mm: read memory information without popen

--------------



warren.xiong



>On 8/3/26 03:30, Warren Xiong wrote:



>> read_memory_info() invokes two shell pipelines to obtain MemFree and



>> Hugepagesize from /proc/meminfo. It does not check whether popen()



>> returns NULL before passing the result to fgets(), and it does not call



>> pclose() when fgets() fails.



>> 



>> Open /proc/meminfo directly and obtain both values in a single pass.



>> This removes the unchecked NULL path, closes the file on all paths, and



>> avoids dependencies on external commands.



>> 



>> The compaction test continues to pass after this change.



>> 



>> Signed-off-by: Warren Xiong <[email protected]>



>> ---



>>  tools/testing/selftests/mm/compaction_test.c | 43 +++++++++++++++++-----------



>>  1 file changed, 27 insertions(+), 16 deletions(-)



>> 



>> diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c



>> index 5b58258..0df2000 100644



>> --- a/tools/testing/selftests/mm/compaction_test.c



>> +++ b/tools/testing/selftests/mm/compaction_test.c



>> @@ -7,6 +7,7 @@



>>   * allocated.



>>   */



>>  



>> +#include <stdbool.h>



>>  #include <stdio.h>



>>  #include <stdlib.h>



>>  #include <sys/mman.h>



>> @@ -29,30 +30,40 @@ struct map_list {



>>  



>>  int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)



>>  {



>



>Looks much better indeed.



>



>> -	char  buffer[256] = {0};



>> -	char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'";



>> -	FILE *cmdfile = popen(cmd, "r");



>> +	char buffer[256];



>> +	bool memfree_found = false;



>> +	bool hugepagesize_found = false;



>> +	FILE *file;



>> +	int ret = -1;



>>  



>> -	if (!(fgets(buffer, sizeof(buffer), cmdfile))) {



>> -		ksft_print_msg("Failed to read meminfo: %s\n", strerror(errno));



>> +	file = fopen("/proc/meminfo", "r");



>> +	if (!file) {



>> +		ksft_print_msg("Failed to open /proc/meminfo: %s\n",



>> +			       strerror(errno));



>>  		return -1;



>>  	}



>>  



>> -	pclose(cmdfile);



>> +	while (fgets(buffer, sizeof(buffer), file)) {



>> +		if (sscanf(buffer, "MemFree: %lu kB", memfree) == 1)



>> +			memfree_found = true;



>> +		else if (sscanf(buffer, "Hugepagesize: %lu kB",



>> +				hugepagesize) == 1)



>> +			hugepagesize_found = true;



>Instead of these bools you could just have a hit-count.

Thanks for the review.

Agreed, a hit count is sufficient here and makes the code simpler.  I
have incorporated this change and will send v2 shortly.

Thanks,
Warren



>



>Like the following on top:



>



>diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c



>index 0df2000f4a2b1..30d4ace7155ae 100644



>--- a/tools/testing/selftests/mm/compaction_test.c



>+++ b/tools/testing/selftests/mm/compaction_test.c



>@@ -7,7 +7,6 @@



>  * allocated.



>  */



>



>-#include <stdbool.h>



> #include <stdio.h>



> #include <stdlib.h>



> #include <sys/mman.h>



>@@ -31,8 +30,7 @@ struct map_list {



> int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)



> {



>        char buffer[256];



>-       bool memfree_found = false;



>-       bool hugepagesize_found = false;



>+       int found = 0;



>        FILE *file;



>        int ret = -1;



>



>@@ -43,24 +41,19 @@ int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)



>                return -1;



>        }



>



>-       while (fgets(buffer, sizeof(buffer), file)) {



>-               if (sscanf(buffer, "MemFree: %lu kB", memfree) == 1)



>-                       memfree_found = true;



>-               else if (sscanf(buffer, "Hugepagesize: %lu kB",



>-                               hugepagesize) == 1)



>-                       hugepagesize_found = true;



>-



>-               if (memfree_found && hugepagesize_found) {



>-                       ret = 0;



>-                       break;



>-               }



>+       while (fgets(buffer, sizeof(buffer), file) && found != 2) {



>+               if (sscanf(buffer, "MemFree: %lu kB", memfree) == 1 ||



>+                   sscanf(buffer, "Hugepagesize: %lu kB", hugepagesize) == 1)



>+                       found++;



>        }



>



>        if (ferror(file))



>                ksft_print_msg("Failed to read /proc/meminfo: %s\n",



>                               strerror(errno));



>-       else if (ret)



>+       else if (found != 2)



>                ksft_print_msg("Failed to parse /proc/meminfo\n");



>+       else



>+               ret = 0;



>



>        fclose(file);



>        return ret;



>



>



>-- 



>Cheers,



>



>David



>