On 09.04.25 12:25, Anshuman Khandual wrote:
On 4/9/25 15:51, David Hildenbrand wrote:
On 09.04.25 12:09, Anshuman Khandual wrote:
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.
This is something the compiler should clearly be able to verify. before_fork is
never changed in that function.
We should not work around wrong compilers.
Which compiler are you using such that you run into this issue?
gcc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
gcc (GCC) 14.2.1 20250110 (Red Hat 14.2.1-7)
Seems to be fine, just like all other compilers people used with this
over the years.
Maybe something about that compiler is shaky that was fixed in the meantime?
--
Cheers,
David / dhildenb
