From: Petr Machata <petrm@mellanox•com>
To: Cong Wang <xiyou.wangcong@gmail•com>
Cc: Linux Kernel Network Developers <netdev@vger•kernel.org>,
David Miller <davem@davemloft•net>,
Jakub Kicinski <kuba@kernel•org>,
Eric Dumazet <eric.dumazet@gmail•com>,
Jiri Pirko <jiri@mellanox•com>,
Ido Schimmel <idosch@mellanox•com>
Subject: Re: [PATCH net-next v1 2/5] net: sched: Introduce helpers for qevent blocks
Date: Wed, 08 Jul 2020 23:04:36 +0200 [thread overview]
Message-ID: <87wo3dhg63.fsf@mellanox.com> (raw)
In-Reply-To: <CAM_iQpVs_OEBw54qMhn7Tx6_YAGh5PMSApj=RrO0j6ThSXpkcg@mail.gmail.com>
Cong Wang <xiyou.wangcong@gmail•com> writes:
> On Wed, Jul 8, 2020 at 5:35 AM Petr Machata <petrm@mellanox•com> wrote:
>> Do you have another solution in mind here? I think the deadlock (in both
>> classification and qevents) is an issue, but really don't know how to
>> avoid it except by dropping the lock.
>
> Ideally we should only take the lock once, but it clearly requires some
> work to teach the dev_queue_xmit() in act_mirred not to acquire it again.
act_mirred does not acquire it though. The egress path does. And the
packet can traverse several mirred instances on several devices before
it gets to the deadlock. Currently I don't see a way to give the egress
path a way to know that the lock is already taken.
I'll think about it some more. For now I will at least fix the lack of
locking.
next prev parent reply other threads:[~2020-07-08 21:04 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-26 22:45 [PATCH net-next v1 0/5] TC: Introduce qevents Petr Machata
2020-06-26 22:45 ` [PATCH net-next v1 1/5] net: sched: Pass root lock to Qdisc_ops.enqueue Petr Machata
2020-07-06 19:21 ` Cong Wang
2020-07-07 15:25 ` Petr Machata
2020-07-07 19:41 ` Cong Wang
2020-06-26 22:45 ` [PATCH net-next v1 2/5] net: sched: Introduce helpers for qevent blocks Petr Machata
2020-07-06 19:48 ` Cong Wang
2020-07-07 15:22 ` Petr Machata
2020-07-07 19:13 ` Cong Wang
2020-07-08 12:35 ` Petr Machata
2020-07-08 16:21 ` Petr Machata
2020-07-08 19:09 ` Cong Wang
2020-07-08 19:04 ` Cong Wang
2020-07-08 21:04 ` Petr Machata [this message]
2020-07-09 0:13 ` Petr Machata
2020-07-09 19:37 ` Cong Wang
2020-07-10 14:40 ` Petr Machata
2020-07-14 2:51 ` Cong Wang
2020-07-14 9:12 ` Petr Machata
2020-07-07 19:48 ` Cong Wang
2020-07-08 9:19 ` Petr Machata
2020-06-26 22:45 ` [PATCH net-next v1 3/5] net: sched: sch_red: Split init and change callbacks Petr Machata
2020-06-26 22:45 ` [PATCH net-next v1 4/5] net: sched: sch_red: Add qevents "early_drop" and "mark" Petr Machata
2020-06-26 22:45 ` [PATCH net-next v1 5/5] selftests: forwarding: Add a RED test for SW datapath Petr Machata
2020-06-26 22:45 ` [PATCH iproute2-next v1 1/4] uapi: pkt_sched: Add two new RED attributes Petr Machata
2020-06-26 22:45 ` [PATCH iproute2-next v1 2/4] tc: Add helpers to support qevent handling Petr Machata
2020-06-26 22:45 ` [PATCH iproute2-next v1 3/4] man: tc: Describe qevents Petr Machata
2020-06-26 22:45 ` [PATCH iproute2-next v1 4/4] tc: q_red: Add support for qevents "mark" and "early_drop" Petr Machata
2020-06-26 22:56 ` [PATCH net-next v1 0/5] TC: Introduce qevents Stephen Hemminger
2020-06-29 13:21 ` Petr Machata
2020-06-30 0:15 ` David Miller
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