From: Jonathan Lemon <bsd@xxxxxx>
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@xxxxxxxxx>
---
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
