Messages in this thread Patch in this message | | | Date | Thu, 24 Aug 2023 16:32:01 +0200 | From | Oleg Nesterov <> | Subject | [PATCH 2/2] change next_thread() to use __next_thread() ?: group_leader |
| |
This relies on fact that group leader is always the 1st entry in the signal->thread_head list.
With or without this change, if the lockless next_thread(last_thread) races with exec it can return the old or the new leader.
We are almost ready to kill task->thread_group, after this change its only user is thread_group_empty().
Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- include/linux/sched/signal.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 7fb34b8cda54..cffc882d367f 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -726,10 +726,9 @@ static inline struct task_struct *__next_thread(struct task_struct *p) thread_node); } -static inline struct task_struct *next_thread(const struct task_struct *p) +static inline struct task_struct *next_thread(struct task_struct *p) { - return list_entry_rcu(p->thread_group.next, - struct task_struct, thread_group); + return __next_thread(p) ?: p->group_leader; } static inline int thread_group_empty(struct task_struct *p) -- 2.25.1.362.g51ebf55
| |