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From: David Carlier <devnexen@gmail.com>
To: Tejun Heo <tj@kernel.org>, David Vernet <void@manifault.com>
Cc: linux-kernel@vger.kernel.org, David Carlier <devnexen@gmail.com>
Subject: [PATCH] sched_ext: Fix SCX_EFLAG_INITIALIZED being a no-op flag
Date: Thu, 26 Feb 2026 12:45:17 +0000	[thread overview]
Message-ID: <20260226124517.32643-1-devnexen@gmail.com> (raw)

SCX_EFLAG_INITIALIZED is the sole member of enum scx_exit_flags with no
explicit value, so the compiler assigns it 0. This makes the bitwise OR
in scx_ops_init() a no-op:

    sch->exit_info->flags |= SCX_EFLAG_INITIALIZED; /* |= 0 */

As a result, BPF schedulers cannot distinguish whether ops.init()
completed successfully by inspecting exit_info->flags.

Assign the value 1LLU << 0 so the flag is actually set.

Signed-off-by: David Carlier <devnexen@gmail.com>
---
 kernel/sched/ext_internal.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/ext_internal.h b/kernel/sched/ext_internal.h
index 386c677e4c9a..11ebb744d893 100644
--- a/kernel/sched/ext_internal.h
+++ b/kernel/sched/ext_internal.h
@@ -74,7 +74,7 @@ enum scx_exit_flags {
 	 * info communication. The following flag indicates whether ops.init()
 	 * finished successfully.
 	 */
-	SCX_EFLAG_INITIALIZED,
+	SCX_EFLAG_INITIALIZED   = 1LLU << 0,
 };
 
 /*
-- 
2.51.0


             reply	other threads:[~2026-02-26 12:45 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-26 12:45 David Carlier [this message]
2026-02-26 22:07 ` [PATCH] sched_ext: Fix SCX_EFLAG_INITIALIZED being a no-op flag Tejun Heo

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