Optimize the err variable assignment location so that the err variable
is manually modified when an error occurs.
Signed-off-by: Li kunyu <[email protected]>
---
kernel/utsname.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/kernel/utsname.c b/kernel/utsname.c
index b1ac3ca870f24..f55568e00927c 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -49,15 +49,17 @@ static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
struct ucounts *ucounts;
int err;
- err = -ENOSPC;
ucounts = inc_uts_namespaces(user_ns);
- if (!ucounts)
+ if (!ucounts) {
+ err = -ENOSPC;
goto fail;
+ }
- err = -ENOMEM;
ns = create_uts_ns();
- if (!ns)
+ if (!ns) {
+ err = -ENOMEM;
goto fail_dec;
+ }
err = ns_alloc_inum(&ns->ns);
if (err)
--
2.18.2
On Mon, Jan 15, 2024 at 02:11:27PM +0800, Li kunyu wrote:
> Optimize the err variable assignment location so that the err variable
> is manually modified when an error occurs.
First of all, this is *not* an optimization in any meaningful sense -
compiler is perfectly capable to shift those assignments (from either
form) and choose whatever it prefers.
Incidentally, it might end up lifting the store out of if - it's
entirely possible that
r1 = v
flag = (r2 == 0)
if flag goto fail
is better than
flag = (r2 == 0)
if flag goto l
...
l:
r1 = v
goto fail
provided that assignment to r1 and checking r2 can be done in parallel
and that's assuming that it will figure out that branch is unlikely.
Readability might be a good reason; optimization... no. Leave that to
compiler; it will override your choice here anyway.