From: Oleg Nesterov <oleg@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>, Yonghong Song <yhs@fb.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Kui-Feng Lee <kuifeng@fb.com>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@kernel.org>,
bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 0/6] bpf: task_group_seq_get_next: use __next_thread()
Date: Fri, 25 Aug 2023 18:18:42 +0200 [thread overview]
Message-ID: <20230825161842.GA16750@redhat.com> (raw)
Compile tested, 1-5 need the review from bpf maintainers, quite possibly
I did some silly mistakes. I tried to cleanup this code because I could
not look at it, but it has other problems and imo should be rewritten.
6/6 obviously depends on
[PATCH 1/2] introduce __next_thread(), fix next_tid() vs exec() race
https://lore.kernel.org/all/20230824143142.GA31222@redhat.com/
which was not merged yet.
To simplify the review, this is the code after 6/6:
static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_common *common,
u32 *tid,
bool skip_if_dup_files)
{
struct task_struct *task;
struct pid *pid;
u32 next_tid;
if (!*tid) {
/* The first time, the iterator calls this function. */
pid = find_pid_ns(common->pid, common->ns);
task = get_pid_task(pid, PIDTYPE_TGID);
if (!task)
return NULL;
*tid = common->pid;
common->pid_visiting = common->pid;
return task;
}
/* If the control returns to user space and comes back to the
* kernel again, *tid and common->pid_visiting should be the
* same for task_seq_start() to pick up the correct task.
*/
if (*tid == common->pid_visiting) {
pid = find_pid_ns(common->pid_visiting, common->ns);
task = get_pid_task(pid, PIDTYPE_PID);
return task;
}
task = find_task_by_pid_ns(common->pid_visiting, common->ns);
if (!task)
return NULL;
retry:
task = __next_thread(task);
if (!task)
return NULL;
next_tid = __task_pid_nr_ns(task, PIDTYPE_PID, common->ns);
if (!next_tid)
goto retry;
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;
}
Oleg.
next reply other threads:[~2023-08-25 16:21 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-25 16:18 Oleg Nesterov [this message]
2023-08-25 16:19 ` [PATCH 1/6] bpf: task_group_seq_get_next: cleanup the usage of next_thread() Oleg Nesterov
2023-08-25 22:45 ` Yonghong Song
2023-08-25 16:19 ` [PATCH 2/6] bpf: task_group_seq_get_next: cleanup the usage of get/put_task_struct Oleg Nesterov
2023-08-25 16:19 ` [PATCH 3/6] bpf: task_group_seq_get_next: fix the skip_if_dup_files check Oleg Nesterov
2023-08-25 17:04 ` Oleg Nesterov
2023-08-25 22:52 ` Yonghong Song
2023-08-27 20:19 ` Oleg Nesterov
2023-08-28 1:18 ` Yonghong Song
2023-08-28 10:54 ` Oleg Nesterov
2023-08-29 0:30 ` Yonghong Song
2023-08-30 23:54 ` Oleg Nesterov
2023-08-31 11:29 ` Yonghong Song
2023-08-31 12:06 ` Oleg Nesterov
2023-08-25 22:49 ` Yonghong Song
2023-08-25 16:19 ` [PATCH 4/6] bpf: task_group_seq_get_next: kill next_task Oleg Nesterov
2023-08-25 22:55 ` Yonghong Song
2023-08-25 16:19 ` [PATCH 5/6] bpf: task_group_seq_get_next: simplify the "next tid" logic Oleg Nesterov
2023-08-25 22:57 ` Yonghong Song
2023-08-25 16:19 ` [PATCH 6/6] bpf: task_group_seq_get_next: use __next_thread() rather than next_thread() Oleg Nesterov
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