From: Changwoo Min <changwoo@igalia.com>
Date: Sun, 2 Feb 2025 03:37:48 +0000 (+0900)
Subject: sched_ext: Fix incorrect time delta calculation in time_delta()
X-Git-Tag: v6.14-rc3~27^2~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=029b6ce733712a41421955194b113f283dcb1026;p=thirdparty%2Fkernel%2Fstable.git

sched_ext: Fix incorrect time delta calculation in time_delta()

When (s64)(after - before) > 0, the code returns the result of
(s64)(after - before) > 0 while the intended result should be
(s64)(after - before). That happens because the middle operand of
the ternary operator was omitted incorrectly, returning the result of
(s64)(after - before) > 0. Thus, add the middle operand
-- (s64)(after - before) -- to return the correct time calculation.

Fixes: d07be814fc71 ("sched_ext: Add time helpers for BPF schedulers")
Signed-off-by: Changwoo Min <changwoo@igalia.com>
Acked-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
---

diff --git a/tools/sched_ext/include/scx/common.bpf.h b/tools/sched_ext/include/scx/common.bpf.h
index f254a39b86a58..d72b60a0c582c 100644
--- a/tools/sched_ext/include/scx/common.bpf.h
+++ b/tools/sched_ext/include/scx/common.bpf.h
@@ -432,7 +432,7 @@ void bpf_rcu_read_unlock(void) __ksym;
  */
 static inline s64 time_delta(u64 after, u64 before)
 {
-	return (s64)(after - before) > 0 ? : 0;
+	return (s64)(after - before) > 0 ? (s64)(after - before) : 0;
 }
 
 /**