From: Oleg Nesterov Date: Tue, 5 Sep 2023 15:46:49 +0000 (+0200) Subject: bpf: task_group_seq_get_next: cleanup the usage of get/put_task_struct X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=4981921350452a7639fac9ac8f19be4d25febdca;p=users%2Fjedix%2Flinux-maple.git 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: Oleg Nesterov Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20230905154649.GA24935@redhat.com Signed-off-by: Alexei Starovoitov --- diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index 4d1125108014..1589ec3faded 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -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; }