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 5/6] bpf: task_group_seq_get_next: simplify the "next tid" logic
Date: Fri, 25 Aug 2023 18:19:54 +0200 [thread overview]
Message-ID: <20230825161954.GA16886@redhat.com> (raw)
In-Reply-To: <20230825161842.GA16750@redhat.com>
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: Oleg Nesterov <oleg@redhat.com>
---
kernel/bpf/task_iter.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index f51f476ec679..7473068ed313 100644
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -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;
}
--
2.25.1.362.g51ebf55
next prev parent reply other threads:[~2023-08-25 16:22 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-25 16:18 [PATCH 0/6] bpf: task_group_seq_get_next: use __next_thread() Oleg Nesterov
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 ` Oleg Nesterov [this message]
2023-08-25 22:57 ` [PATCH 5/6] bpf: task_group_seq_get_next: simplify the "next tid" logic 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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