[PATCH v2] selftests/proc: fix unused result warning during test compilation

[Abhinav Jain]

Check the return value from write function to get rid of the warning
during test compilation, shared below.
Tested by compiling after the change, the warning disappears.

proc-empty-vm.c:385:17: warning: ignoring return value of ‘write’
declared with attribute ‘warn_unused_result’ [-Wunused-result]
  385 |                 write(1, buf, rv);

Signed-off-by: Abhinav Jain <jain.abhinav177@xxxxxxxxx>
---
Changes since v1:
 - Remove the redundant if(0) block as per the feedback
 - Patch v1:
https://lore.kernel.org/all/20240625152139.16412-1-jain.abhinav177@xxxxxxxxx/
---
 tools/testing/selftests/proc/proc-empty-vm.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/proc/proc-empty-vm.c b/tools/testing/selftests/proc/proc-empty-vm.c
index 56198d4ca2bf..123c622cd816 100644
--- a/tools/testing/selftests/proc/proc-empty-vm.c
+++ b/tools/testing/selftests/proc/proc-empty-vm.c
@@ -381,8 +381,12 @@ static int test_proc_pid_statm(pid_t pid)
 
 	assert(rv >= 0);
 	assert(rv <= sizeof(buf));
-	if (0) {
-		write(1, buf, rv);
+
+	ssize_t bytes_written = write(1, buf, rv);
+
+	if (bytes_written != rv) {
+		perror("write");
+		return EXIT_FAILURE;
 	}
 
 	const char *p = buf;
-- 
2.34.1