Lockless use of next_thread() should be avoided, kernel/bpf/task_iter.c
is the last user and the usage is wrong.
bpf_iter_task_next() can loop forever, "kit->pos == kit->task" can never
happen if kit->pos execs. Change this code to use __next_thread().
With or without this change the usage of kit->pos/task and next_task()
doesn't look nice, see the next patch.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
kernel/bpf/task_iter.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index 51ae15e2b290..d42e08d0d0b7 100644
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -1015,12 +1015,11 @@ __bpf_kfunc struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it)
if (flags == BPF_TASK_ITER_ALL_PROCS)
goto get_next_task;
- kit->pos = next_thread(kit->pos);
- if (kit->pos == kit->task) {
- if (flags == BPF_TASK_ITER_PROC_THREADS) {
- kit->pos = NULL;
+ kit->pos = __next_thread(kit->pos);
+ if (!kit->pos) {
+ if (flags == BPF_TASK_ITER_PROC_THREADS)
return pos;
- }
+ kit->pos = kit->task;
} else
return pos;
--
2.25.1.362.g51ebf55
