Re: [PATCH net 6/6] net/sched: qdisc_destroy() old ingress and clsact Qdiscs before grafting
From: Jakub Kicinski <kuba@kernel.org>
Date: 2023-05-17 18:48:31
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On Fri, 5 May 2023 17:16:10 -0700 Peilin Ye wrote:
} else {
- dev_queue = dev_ingress_queue(dev);
- old = dev_graft_qdisc(dev_queue, new);
+ old = dev_graft_qdisc(dev_queue, NULL);
+
+ /* {ingress,clsact}_destroy() "old" before grafting "new" to avoid
+ * unprotected concurrent accesses to net_device::miniq_{in,e}gress
+ * pointer(s) in mini_qdisc_pair_swap().
+ */
+ qdisc_notify(net, skb, n, classid, old, new, extack);
+ qdisc_destroy(old);
+
+ dev_graft_qdisc(dev_queue, new);BTW can't @old be NULL here?