diff options
| author | Tejun Heo <tj@kernel.org> | 2026-04-10 07:54:06 -1000 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2026-04-10 07:54:06 -1000 |
| commit | e719e17d99aaf3922dbc15ae3ac3bb62fac32bad (patch) | |
| tree | 8d32eeffa5016bc380678a426914f646833f15be /kernel | |
| parent | 979a98b6e9bf8ebf11dc3ca260be087606ac4c2c (diff) | |
sched_ext: Warn on task-based SCX op recursion
The kf_tasks[] design assumes task-based SCX ops don't nest - if they
did, kf_tasks[0] would get clobbered. The old scx_kf_allow() WARN_ONCE
caught invalid nesting via kf_mask, but that machinery is gone now.
Add a WARN_ON_ONCE(current->scx.kf_tasks[0]) at the top of each
SCX_CALL_OP_TASK*() macro. Checking kf_tasks[0] alone is sufficient: all
three variants (SCX_CALL_OP_TASK, SCX_CALL_OP_TASK_RET,
SCX_CALL_OP_2TASKS_RET) write to kf_tasks[0], so a non-NULL value at
entry to any of the three means re-entry from somewhere in the family.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Andrea Righi <arighi@nvidia.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/ext.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 40421698c9e3..b8dbae251fd5 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -502,10 +502,13 @@ do { \ * held by try_to_wake_up() with rq tracking via scx_rq.in_select_cpu. So if * kf_tasks[] is set, @p's scheduler-protected fields are stable. * - * These macros only work for non-nesting ops since kf_tasks[] is not stacked. + * kf_tasks[] can not stack, so task-based SCX ops must not nest. The + * WARN_ON_ONCE() in each macro catches a re-entry of any of the three variants + * while a previous one is still in progress. */ #define SCX_CALL_OP_TASK(sch, op, rq, task, args...) \ do { \ + WARN_ON_ONCE(current->scx.kf_tasks[0]); \ current->scx.kf_tasks[0] = task; \ SCX_CALL_OP((sch), op, rq, task, ##args); \ current->scx.kf_tasks[0] = NULL; \ @@ -514,6 +517,7 @@ do { \ #define SCX_CALL_OP_TASK_RET(sch, op, rq, task, args...) \ ({ \ __typeof__((sch)->ops.op(task, ##args)) __ret; \ + WARN_ON_ONCE(current->scx.kf_tasks[0]); \ current->scx.kf_tasks[0] = task; \ __ret = SCX_CALL_OP_RET((sch), op, rq, task, ##args); \ current->scx.kf_tasks[0] = NULL; \ @@ -523,6 +527,7 @@ do { \ #define SCX_CALL_OP_2TASKS_RET(sch, op, rq, task0, task1, args...) \ ({ \ __typeof__((sch)->ops.op(task0, task1, ##args)) __ret; \ + WARN_ON_ONCE(current->scx.kf_tasks[0]); \ current->scx.kf_tasks[0] = task0; \ current->scx.kf_tasks[1] = task1; \ __ret = SCX_CALL_OP_RET((sch), op, rq, task0, task1, ##args); \ |