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bpf: task_group_seq_get_next: simplify the "next tid" logic

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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>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230905154656.GA24950@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Oleg Nesterov 2023-09-05 17:46:56 +02:00 committed by Alexei Starovoitov
parent 0ee9808b0a
commit 780aa8dfcb
1 changed files with 4 additions and 7 deletions
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11
kernel/bpf/task_iter.c
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@ -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;
}