[PATCH v2] sysctl: Reduce dput(child) calls in proc_sys_fill_cache()

From: Markus Elfring
Date: Wed Oct 23 2024 - 11:29:13 EST


From: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
Date: Wed, 23 Oct 2024 16:54:59 +0200

Replace two dput(child) calls with one that occurs immediately before
the IS_ERR evaluation. This transformation can be performed because
dput() gets called regardless of the value returned by IS_ERR(res).

This issue was transformed by using a script for the
semantic patch language like the following.
<SmPL>
@extended_adjustment@
expression e, f != { mutex_unlock }, x, y;
@@
+f(e);
if (...)
{
<+... when != \( e = x \| y(..., &e, ...) \)
- f(e);
...+>
}
-f(e);
</SmPL>

Signed-off-by: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
---

V2:
* This update suggestion was rebased on source files of the software
“Linux next-20241023”.

* The change description was adjusted according to the wording preferences
by Joel Granados.

* An SmPL script example was appended.


fs/proc/proc_sysctl.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 9b9dfc450cb3..b277a1ca392e 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -698,11 +698,11 @@ static bool proc_sys_fill_cache(struct file *file,
res = d_splice_alias(inode, child);
d_lookup_done(child);
if (unlikely(res)) {
- if (IS_ERR(res)) {
- dput(child);
- return false;
- }
dput(child);
+
+ if (IS_ERR(res))
+ return false;
+
child = res;
}
}
--
2.47.0