Messages in this thread | | | Date | Mon, 15 May 2023 15:45:15 -0700 | From | Peilin Ye <> | Subject | Re: [PATCH net 6/6] net/sched: qdisc_destroy() old ingress and clsact Qdiscs before grafting |
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On Thu, May 11, 2023 at 05:11:23PM -0700, Peilin Ye wrote: > > > ->init() may be too early, aren't there any error points which could > > > prevent the Qdisc from binding after ->init() was called? > > > > You're right, it's in qdisc_create(), argh... > > ->destroy() is called for all error points between ->init() and > dev_graft_qdisc(). I'll try handling it in ->destroy().
Sorry for any confusion: there is no point at all undoing "setting dev pointer to b1" in ->destroy() because datapath has already been affected.
To summarize, grafting B mustn't fail after setting dev pointer to b1, so ->init() is too early, because e.g. if user requested [1] to create a rate estimator, gen_new_estimator() could fail after ->init() in qdisc_create().
On the other hand, ->attach() is too late because it's later than dev_graft_qdisc(), so concurrent filter requests might see uninitialized dev pointer in theory.
Please suggest; is adding another callback (or calling ->attach()) right before dev_graft_qdisc() for ingress (clsact) Qdiscs too much for this fix?
[1] e.g. $ tc qdisc add dev eth0 estimator 1s 8s clsact
Thanks, Peilin Ye
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