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From: Changwoo Min <changwoo@igalia.com>
To: tj@kernel.org, void@manifault.com, arighi@nvidia.com
Cc: kernel-dev@igalia.com, linux-kernel@vger.kernel.org,
	Changwoo Min <changwoo@igalia.com>
Subject: [PATCH] sched_ext: Fix incorrect time delta calculation in time_delta()
Date: Sun,  2 Feb 2025 12:37:48 +0900	[thread overview]
Message-ID: <20250202033748.359169-1-changwoo@igalia.com> (raw)

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>
---
 tools/sched_ext/include/scx/common.bpf.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/sched_ext/include/scx/common.bpf.h b/tools/sched_ext/include/scx/common.bpf.h
index f254a39b86a5..d72b60a0c582 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;
 }
 
 /**
-- 
2.48.1


             reply	other threads:[~2025-02-02  3:38 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-02-02  3:37 Changwoo Min [this message]
2025-02-02  6:37 ` [PATCH] sched_ext: Fix incorrect time delta calculation in time_delta() Andrea Righi
2025-02-02 17:42 ` Tejun Heo

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