linux-kernel - [PATCH 4/6] bpf: task_group_seq_get_next: kill next

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Message-ID: <20230825161951.GA16878@redhat.com>
Date:   Fri, 25 Aug 2023 18:19:51 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Yonghong Song <yhs@...com>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kui-Feng Lee <kuifeng@...com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...nel.org>,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 4/6] bpf: task_group_seq_get_next: kill next_task

It only adds the unnecessary confusion and compicates the "retry" code.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/bpf/task_iter.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index 2264870ae3fc..f51f476ec679 100644
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -35,7 +35,7 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm
 						   u32 *tid,
 						   bool skip_if_dup_files)
 {
-	struct task_struct *task, *next_task;
+	struct task_struct *task;
 	struct pid *pid;
 	u32 saved_tid;
 
@@ -68,10 +68,10 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm
 		return NULL;
 
 retry:
-	next_task = next_thread(task);
+	task = next_thread(task);
 
 	saved_tid = *tid;
-	*tid = __task_pid_nr_ns(next_task, PIDTYPE_PID, common->ns);
+	*tid = __task_pid_nr_ns(task, PIDTYPE_PID, common->ns);
 	if (!*tid || *tid == common->pid) {
 		/* Run out of tasks of a process.  The tasks of a
 		 * thread_group are linked as circular linked list.
@@ -82,13 +82,11 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm
 
 	common->pid_visiting = *tid;
 
-	if (skip_if_dup_files && next_task->files == next_task->group_leader->files) {
-		task = next_task;
+	if (skip_if_dup_files && task->files == task->group_leader->files)
 		goto retry;
-	}
 
-	get_task_struct(next_task);
-	return next_task;
+	get_task_struct(task);
+	return task;
 }
 
 static struct task_struct *task_seq_get_next(struct bpf_iter_seq_task_common *common,
-- 
2.25.1.362.g51ebf55