diff options
| author | Andrea Righi <arighi@nvidia.com> | 2025-10-25 00:01:02 +0200 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2025-10-24 12:20:24 -1000 |
| commit | 71d7847cad4475f1f795c7737e08b604b448ca70 (patch) | |
| tree | d889a407e771838f0f5a72e3cb249a2d60793686 /kernel/sched/ext.c | |
| parent | e67708823d7362cfbb557008563cce7e7c9c5128 (diff) | |
sched_ext: Fix scx_bpf_dsq_peek() with FIFO DSQs
When removing a task from a FIFO DSQ, we must delete it from the list
before updating dsq->first_task, otherwise the following lookup will
just re-read the same task, leaving first_task pointing to removed
entry.
This issue only affects DSQs operating in FIFO mode, as priority DSQs
correctly update the rbtree before re-evaluating the new first task.
Remove the item from the list before refreshing the first task to
guarantee the correct behavior in FIFO DSQs.
Fixes: 44f5c8ec5b9ad ("sched_ext: Add lockless peek operation for DSQs")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/sched/ext.c')
| -rw-r--r-- | kernel/sched/ext.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index bde49e47f1e4..1cfe4b43d31b 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -1044,15 +1044,15 @@ static void task_unlink_from_dsq(struct task_struct *p, p->scx.dsq_flags &= ~SCX_TASK_DSQ_ON_PRIQ; } + list_del_init(&p->scx.dsq_list.node); + dsq_mod_nr(dsq, -1); + if (!(dsq->id & SCX_DSQ_FLAG_BUILTIN) && dsq->first_task == p) { struct task_struct *first_task; first_task = nldsq_next_task(dsq, NULL, false); rcu_assign_pointer(dsq->first_task, first_task); } - - list_del_init(&p->scx.dsq_list.node); - dsq_mod_nr(dsq, -1); } static void dispatch_dequeue(struct rq *rq, struct task_struct *p) |