linux-kernel - [PATCH next] cgroup/cpuset: Cleanup signedness issue in cpu_exclusive

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Message-ID: <20230927065801.2139969-1-harshit.m.mogalapalli@oracle.com>
Date:   Tue, 26 Sep 2023 23:58:01 -0700
From:   Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
To:     Waiman Long <longman@...hat.com>,
        Zefan Li <lizefan.x@...edance.com>, Tejun Heo <tj@...nel.org>,
        Johannes Weiner <hannes@...xchg.org>, cgroups@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     dan.carpenter@...aro.org, kernel-janitors@...r.kernel.org,
        error27@...il.com, harshit.m.mogalapalli@...cle.com,
        kamalesh.babulal@...cle.com, kernel test robot <lkp@...el.com>
Subject: [PATCH next] cgroup/cpuset: Cleanup signedness issue in cpu_exclusive_check()

Smatch complains about returning negative error codes from a type
bool function.

kernel/cgroup/cpuset.c:705 cpu_exclusive_check() warn:
	signedness bug returning '(-22)'

The code works correctly, but it is confusing.  The current behavior is
that cpu_exclusive_check() returns true if it's *NOT* exclusive.  Rename
it to cpusets_are_exclusive() and reverse the returns so it returns true
if it is exclusive and false if it's not.  Update both callers as well.

Reported-by: kernel test robot <lkp@...el.com>
Reported-by: Dan Carpenter <error27@...il.com>
Closes: https://lore.kernel.org/r/202309201706.2LhKdM6o-lkp@intel.com/
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
---
This is based on sattic analysis, only compile tested
---
 kernel/cgroup/cpuset.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 15f399153a2e..afefddd33c3e 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -719,18 +719,18 @@ static inline struct cpumask *fetch_xcpus(struct cpuset *cs)
 }
 
 /*
- * cpu_exclusive_check() - check if two cpusets are exclusive
+ * cpusets_are_exclusive() - check if two cpusets are exclusive
  *
- * Return 0 if exclusive, -EINVAL if not
+ * Return true if exclusive, false if not
  */
-static inline bool cpu_exclusive_check(struct cpuset *cs1, struct cpuset *cs2)
+static inline bool cpusets_are_exclusive(struct cpuset *cs1, struct cpuset *cs2)
 {
 	struct cpumask *xcpus1 = fetch_xcpus(cs1);
 	struct cpumask *xcpus2 = fetch_xcpus(cs2);
 
 	if (cpumask_intersects(xcpus1, xcpus2))
-		return -EINVAL;
-	return 0;
+		return false;
+	return true;
 }
 
 /*
@@ -833,7 +833,7 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial)
 	cpuset_for_each_child(c, css, par) {
 		if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
 		    c != cur) {
-			if (cpu_exclusive_check(trial, c))
+			if (!cpusets_are_exclusive(trial, c))
 				goto out;
 		}
 		if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
@@ -1864,7 +1864,7 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd,
 			cpuset_for_each_child(child, css, parent) {
 				if (child == cs)
 					continue;
-				if (cpu_exclusive_check(cs, child)) {
+				if (!cpusets_are_exclusive(cs, child)) {
 					exclusive = false;
 					break;
 				}
-- 
2.41.0