[PATCH] fs: tidy up do_sys_openat2() with likely/unlikely

From: Mateusz Guzik
Date: Thu Mar 20 2025 - 05:25:21 EST


Otherwise gcc 13 generates conditional forward jumps (aka branch
mispredict by default) for build_open_flags() being succesfull.

Signed-off-by: Mateusz Guzik <mjguzik@xxxxxxxxx>
---

maybe i'll get around to do it a full pass instead of sending byte-sized
patchen. someone(tm) should definitely do it.

fs/open.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index bdbf03f799a1..a9063cca9911 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1413,18 +1413,19 @@ static int do_sys_openat2(int dfd, const char __user *filename,
struct open_how *how)
{
struct open_flags op;
- int fd = build_open_flags(how, &op);
struct filename *tmp;
+ int err, fd;

- if (fd)
- return fd;
+ err = build_open_flags(how, &op);
+ if (unlikely(err))
+ return err;

tmp = getname(filename);
if (IS_ERR(tmp))
return PTR_ERR(tmp);

fd = get_unused_fd_flags(how->flags);
- if (fd >= 0) {
+ if (likely(fd >= 0)) {
struct file *f = do_filp_open(dfd, tmp, &op);
if (IS_ERR(f)) {
put_unused_fd(fd);
--
2.43.0