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bpf: task_group_seq_get_next: cleanup the usage of get/put_task_struct

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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: Oleg Nesterov <oleg@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230905154649.GA24935@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Oleg Nesterov 2023-09-05 17:46:49 +02:00 committed by Alexei Starovoitov
parent 1a00ef57d9
commit 4981921350
1 changed files with 2 additions and 10 deletions
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12
kernel/bpf/task_iter.c
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@ -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 @@ retry:
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 @@ retry:
goto retry;
}
get_task_struct(next_task);
return next_task;
}