[PATCH] sched_ext: Fix SCX_EFLAG_INITIALIZED being a no-op flag

David Carlier posted 1 patch 1 month, 1 week ago
kernel/sched/ext_internal.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
[PATCH] sched_ext: Fix SCX_EFLAG_INITIALIZED being a no-op flag
Posted by David Carlier 1 month, 1 week ago
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
Re: [PATCH] sched_ext: Fix SCX_EFLAG_INITIALIZED being a no-op flag
Posted by Tejun Heo 1 month, 1 week ago
Hello,

Applied to sched_ext/for-7.0-fixes with Fixes tag added.

Thanks.

--
tejun