On 4/9/25 15:27, David Hildenbrand wrote:
> On 09.04.25 11:50, Anshuman Khandual wrote:
>> Following build warning comes up for cow test as 'transferred' variable has
>> not been initialized. Fix the warning via zero init for the variable.
>>
>> CC cow
>> cow.c: In function ‘do_test_vmsplice_in_parent’:
>> cow.c:365:61: warning: ‘transferred’ may be used uninitialized
>> [-Wmaybe-uninitialized]
>> 365 | cur = read(fds[0], new + total, transferred -
>> total);
>> | ~~~~~~~~~~~~^~~~~~~
>> cow.c:296:29: note: ‘transferred’ was declared here
>> 296 | ssize_t cur, total, transferred;
>> | ^~~~~~~~~~~
>> CC compaction_test
>> CC gup_longterm
>>
>> Cc: Andrew Morton <a...@linux-foundation.org>
>> Cc: Shuah Khan <sh...@kernel.org>
>> Cc: linux...@kvack.org
>> Cc: linux-kselft...@vger.kernel.org
>> Cc: linux-kernel@vger.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khand...@arm.com>
>> ---
>> tools/testing/selftests/mm/cow.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/tools/testing/selftests/mm/cow.c
>> b/tools/testing/selftests/mm/cow.c
>> index f0cb14ea8608..b6cfe0a4b7df 100644
>> --- a/tools/testing/selftests/mm/cow.c
>> +++ b/tools/testing/selftests/mm/cow.c
>> @@ -293,7 +293,7 @@ static void do_test_vmsplice_in_parent(char *mem, size_t
>> size,
>> .iov_base = mem,
>> .iov_len = size,
>> };
>> - ssize_t cur, total, transferred;
>> + ssize_t cur, total, transferred = 0;
>> struct comm_pipes comm_pipes;
>> char *old, *new;
>> int ret, fds[2];
>
>
> if (before_fork) {
> transferred = vmsplice(fds[1], &iov, 1, 0);
> ...
>
> if (!before_fork) {
> transferred = vmsplice(fds[1], &iov, 1, 0);
> ...
>
> for (total = 0; total < transferred; total += cur) {
> ...
>
>
> And I don't see any jump label that could jump to code that would ve using
> transferred.
>
> What am I missing?
Probably because both those conditional statements are not mutually
exclusive above with an if-else construct. Hence compiler flags it
rather as a false positive ? Initializing with 0 just works around
that false positive.
