Commit 780aa8df authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Alexei Starovoitov
Browse files

bpf: task_group_seq_get_next: simplify the "next tid" logic 



Kill saved_tid. It looks ugly to update *tid and then restore the
previous value if __task_pid_nr_ns() returns 0. Change this code
to update *tid and common->pid_visiting once before return.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarYonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230905154656.GA24950@redhat.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 0ee9808b

kernel/bpf/task_iter.c

+4 −7
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm 
{

	struct task_struct *task;

	struct pid *pid;

	u32 saved_tid;

	u32 next_tid;



	if (!*tid) {

		/* The first time, the iterator calls this function. */
@@ -70,21 +70,18 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm 
retry:

	task = next_thread(task);



	saved_tid = *tid;

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

	if (!*tid || *tid == common->pid) {

	next_tid = __task_pid_nr_ns(task, PIDTYPE_PID, common->ns);

	if (!next_tid || next_tid == common->pid) {

		/* Run out of tasks of a process.  The tasks of a

		 * thread_group are linked as circular linked list.

		 */

		*tid = saved_tid;

		return NULL;

	}



	common->pid_visiting = *tid;



	if (skip_if_dup_files && task->files == task->group_leader->files)

		goto retry;



	*tid = common->pid_visiting = next_tid;

	get_task_struct(task);

	return task;

}