diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2023-11-14 17:32:37 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-11-19 11:43:44 -0800 |
| commit | 5a34f9dabd9aa567e2d37e1aa27a67f80acfaa1c (patch) | |
| tree | c070c12042571603f0516ae4a95be695cb98dc00 /kernel/bpf/task_iter.c | |
| parent | 2d1618054f25e11c44d189dbff4a60342a4cfb4b (diff) | |
bpf: bpf_iter_task_next: use __next_thread() rather than next_thread()
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@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231114163237.GA897@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/task_iter.c')
| -rw-r--r-- | kernel/bpf/task_iter.c | 9 |
1 files 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; |