--------------
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
>
