Commit 49819213 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Alexei Starovoitov
Browse files

bpf: task_group_seq_get_next: cleanup the usage of get/put_task_struct 



get_pid_task() makes no sense, the code does put_task_struct() soon after.
Use find_task_by_pid_ns() instead of find_pid_ns + get_pid_task and kill
put_task_struct(), this allows to do get_task_struct() only once before
return.

While at it, kill the unnecessary "if (!pid)" check in the "if (!*tid)"
block, this matches the next usage of find_pid_ns() + get_pid_task() in
this function.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarYonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230905154649.GA24935@redhat.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 1a00ef57

kernel/bpf/task_iter.c

+2 −10
Original line number Diff line number Diff line
@@ -42,9 +42,6 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm 
	if (!*tid) {

		/* The first time, the iterator calls this function. */

		pid = find_pid_ns(common->pid, common->ns);

		if (!pid)

			return NULL;



		task = get_pid_task(pid, PIDTYPE_TGID);

		if (!task)

			return NULL;
@@ -66,17 +63,12 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm 
		return task;

	}



	pid = find_pid_ns(common->pid_visiting, common->ns);

	if (!pid)

		return NULL;



	task = get_pid_task(pid, PIDTYPE_PID);

	task = find_task_by_pid_ns(common->pid_visiting, common->ns);

	if (!task)

		return NULL;



retry:

	next_task = next_thread(task);

	put_task_struct(task);



	saved_tid = *tid;

	*tid = __task_pid_nr_ns(next_task, PIDTYPE_PID, common->ns);
@@ -88,7 +80,6 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm 
		return NULL;

	}



	get_task_struct(next_task);

	common->pid_visiting = *tid;



	if (skip_if_dup_files && task->files == task->group_leader->files) {
@@ -96,6 +87,7 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm 
		goto retry;

	}



	get_task_struct(next_task);

	return next_task;

}