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Date: Fri, 18 Dec 2020 10:50:32 -0800 From: Jonathan Lemon <jonathan.lemon@...il.com> To: <netdev@...r.kernel.org>, <ast@...nel.org>, <daniel@...earbox.net>, <yhs@...com>, <bpf@...r.kernel.org> CC: <kernel-team@...com> Subject: [PATCH 3/3 v4 bpf-next] bpf: optimize task iteration From: Jonathan Lemon <bsd@...com> Only obtain the task reference count at the end of the RCU section instead of repeatedly obtaining/releasing it when iterating though a thread group. Jump to the correct branch when it is known that the task is NULL. Signed-off-by: Jonathan Lemon <jonathan.lemon@...il.com> --- kernel/bpf/task_iter.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index dc4007f1843b..598a8d7da5bf 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -33,7 +33,7 @@ static struct task_struct *task_seq_get_next(struct pid_namespace *ns, pid = find_ge_pid(*tid, ns); if (pid) { *tid = pid_nr_ns(pid, ns); - task = get_pid_task(pid, PIDTYPE_PID); + task = pid_task(pid, PIDTYPE_PID); if (!task) { ++*tid; goto retry; @@ -44,6 +44,7 @@ static struct task_struct *task_seq_get_next(struct pid_namespace *ns, ++*tid; goto retry; } + get_task_struct(task); } rcu_read_unlock(); @@ -148,12 +149,12 @@ task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info) * it held a reference to the task/files_struct/file. * Otherwise, it does not hold any reference. */ -again: if (info->task) { curr_task = info->task; curr_files = info->files; curr_fd = info->fd; } else { +again: curr_task = task_seq_get_next(ns, &curr_tid, true); if (!curr_task) { info->task = NULL; -- 2.24.1
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