[LTP] [PATCH 3/5] fanotify21: Simplify read_pidfd_fdinfo()

[AnonymeMeow]

Let callers provide storage for struct pidfd_fdinfo_t instead of
allocating it in read_pidfd_fdinfo() every time. This removes
unnecessary allocation/free paths and the NULL checks after
read_pidfd_fdinfo() and simplifies the code.

Signed-off-by: AnonymeMeow <anonymemeow@gmail.com>
---
 .../kernel/syscalls/fanotify/fanotify21.c     | 61 ++++++-------------
 1 file changed, 20 insertions(+), 41 deletions(-)

diff --git a/testcases/kernel/syscalls/fanotify/fanotify21.c b/testcases/kernel/syscalls/fanotify/fanotify21.c
index bd1a43513..22f9767db 100644
--- a/testcases/kernel/syscalls/fanotify/fanotify21.c
+++ b/testcases/kernel/syscalls/fanotify/fanotify21.c
@@ -64,7 +64,7 @@ static struct test_case_t {
 
 static int fanotify_fd;
 static char event_buf[BUF_SZ];
-static struct pidfd_fdinfo_t *self_pidfd_fdinfo;
+static struct pidfd_fdinfo_t exp_pidfd_fdinfo;
 
 static int fd_error_unsupported;
 
@@ -73,12 +73,9 @@ static struct tst_clone_args clone_args = {
 	.exit_signal = SIGCHLD,
 };
 
-static struct pidfd_fdinfo_t *read_pidfd_fdinfo(int pidfd)
+static void read_pidfd_fdinfo(int pidfd, struct pidfd_fdinfo_t *pidfd_fdinfo)
 {
 	char *fdinfo_path;
-	struct pidfd_fdinfo_t *pidfd_fdinfo;
-
-	pidfd_fdinfo = SAFE_MALLOC(sizeof(struct pidfd_fdinfo_t));
 
 	SAFE_ASPRINTF(&fdinfo_path, "/proc/self/fdinfo/%d", pidfd);
 	SAFE_FILE_LINES_SCANF(fdinfo_path, "pos: %d", &pidfd_fdinfo->pos);
@@ -88,8 +85,6 @@ static struct pidfd_fdinfo_t *read_pidfd_fdinfo(int pidfd)
 	SAFE_FILE_LINES_SCANF(fdinfo_path, "NSpid: %d", &pidfd_fdinfo->ns_pid);
 
 	free(fdinfo_path);
-
-	return pidfd_fdinfo;
 }
 
 static void generate_event(void)
@@ -133,12 +128,9 @@ static void do_setup(void)
 
 	pidfd = SAFE_PIDFD_OPEN(getpid(), 0);
 
-	self_pidfd_fdinfo = read_pidfd_fdinfo(pidfd);
-	if (self_pidfd_fdinfo == NULL) {
-		tst_brk(TBROK,
-			"pidfd=%d, failed to read pidfd fdinfo",
-			pidfd);
-	}
+	read_pidfd_fdinfo(pidfd, &exp_pidfd_fdinfo);
+
+	SAFE_CLOSE(pidfd);
 }
 
 static void do_test(unsigned int num)
@@ -195,7 +187,7 @@ static void do_test(unsigned int num)
 	while (i < len) {
 		struct fanotify_event_metadata *event;
 		struct fanotify_event_info_pidfd *info;
-		struct pidfd_fdinfo_t *event_pidfd_fdinfo = NULL;
+		struct pidfd_fdinfo_t event_pidfd_fdinfo;
 
 		event = (struct fanotify_event_metadata *)&event_buf[i];
 		info = (struct fanotify_event_info_pidfd *)(event + 1);
@@ -275,39 +267,32 @@ static void do_test(unsigned int num)
 		 * No pidfd errors occurred, continue with verifying pidfd
 		 * fdinfo validity.
 		 */
-		event_pidfd_fdinfo = read_pidfd_fdinfo(info->pidfd);
-		if (event_pidfd_fdinfo == NULL) {
-			tst_brk(TBROK,
-				"reading fdinfo for pidfd: %d "
-				"describing pid: %u failed",
-				info->pidfd,
-				(unsigned int)event->pid);
-			goto next_event;
-		} else if (event_pidfd_fdinfo->pid != event->pid) {
+		read_pidfd_fdinfo(info->pidfd, &event_pidfd_fdinfo);
+		if (event_pidfd_fdinfo.pid != event->pid) {
 			tst_res(TFAIL,
 				"pidfd provided for incorrect pid "
 				"(expected pidfd for pid: %u, got pidfd for "
 				"pid: %u)",
 				(unsigned int)event->pid,
-				(unsigned int)event_pidfd_fdinfo->pid);
+				(unsigned int)event_pidfd_fdinfo.pid);
 			goto next_event;
-		} else if (memcmp(event_pidfd_fdinfo, self_pidfd_fdinfo,
+		} else if (memcmp(&event_pidfd_fdinfo, &exp_pidfd_fdinfo,
 				  sizeof(struct pidfd_fdinfo_t))) {
 			tst_res(TFAIL,
 				"pidfd fdinfo values for self and event differ "
 				"(expected pos: %d, flags: %x, mnt_id: %d, "
 				"pid: %d, ns_pid: %d, got pos: %d, "
 				"flags: %x, mnt_id: %d, pid: %d, ns_pid: %d",
-				self_pidfd_fdinfo->pos,
-				self_pidfd_fdinfo->flags,
-				self_pidfd_fdinfo->mnt_id,
-				self_pidfd_fdinfo->pid,
-				self_pidfd_fdinfo->ns_pid,
-				event_pidfd_fdinfo->pos,
-				event_pidfd_fdinfo->flags,
-				event_pidfd_fdinfo->mnt_id,
-				event_pidfd_fdinfo->pid,
-				event_pidfd_fdinfo->ns_pid);
+				exp_pidfd_fdinfo.pos,
+				exp_pidfd_fdinfo.flags,
+				exp_pidfd_fdinfo.mnt_id,
+				exp_pidfd_fdinfo.pid,
+				exp_pidfd_fdinfo.ns_pid,
+				event_pidfd_fdinfo.pos,
+				event_pidfd_fdinfo.flags,
+				event_pidfd_fdinfo.mnt_id,
+				event_pidfd_fdinfo.pid,
+				event_pidfd_fdinfo.ns_pid);
 			goto next_event;
 		} else {
 			tst_res(TPASS,
@@ -329,9 +314,6 @@ next_event:
 
 		if (info && info->pidfd >= 0)
 			SAFE_CLOSE(info->pidfd);
-
-		if (event_pidfd_fdinfo)
-			free(event_pidfd_fdinfo);
 	}
 
 	if (tc->want_pidfd_err)
@@ -343,9 +325,6 @@ static void do_cleanup(void)
 	if (fanotify_fd >= 0)
 		SAFE_CLOSE(fanotify_fd);
 
-	if (self_pidfd_fdinfo)
-		free(self_pidfd_fdinfo);
-
 	/* Unmount the bind mount */
 	SAFE_UMOUNT(MOUNT_PATH);
 }
-- 
2.54.0