Commit 1a00ef57 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Alexei Starovoitov
Browse files

bpf: task_group_seq_get_next: cleanup the usage of next_thread() 



1. find_pid_ns() + get_pid_task() under rcu_read_lock() guarantees that we
   can safely iterate the task->thread_group list. Even if this task exits
   right after get_pid_task() (or goto retry) and pid_alive() returns 0.

   Kill the unnecessary pid_alive() check.

2. next_thread() simply can't return NULL, kill the bogus "if (!next_task)"
   check.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: default avatarYonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230905154646.GA24928@redhat.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 35897c3c

kernel/bpf/task_iter.c

+0 −7
Original line number Diff line number Diff line
@@ -75,15 +75,8 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm 
		return NULL;



retry:

	if (!pid_alive(task)) {

		put_task_struct(task);

		return NULL;

	}



	next_task = next_thread(task);

	put_task_struct(task);

	if (!next_task)

		return NULL;



	saved_tid = *tid;

	*tid = __task_pid_nr_ns(next_task, PIDTYPE_PID, common->ns);