netdev - Re: [PATCH v3 04/11] net: sched: always take reference to action

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Date:   Mon, 28 May 2018 16:19:37 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Vlad Buslov <vladbu@...lanox.com>
Cc:     netdev@...r.kernel.org, jhs@...atatu.com, xiyou.wangcong@...il.com,
        davem@...emloft.net, ast@...nel.org, daniel@...earbox.net,
        kliteyn@...lanox.com
Subject: Re: [PATCH v3 04/11] net: sched: always take reference to action

Sun, May 27, 2018 at 11:17:22PM CEST, vladbu@...lanox.com wrote:
>Without rtnl lock protection it is no longer safe to use pointer to tc
>action without holding reference to it. (it can be destroyed concurrently)
>
>Remove unsafe action idr lookup function. Instead of it, implement safe tcf
>idr check function that atomically looks up action in idr and increments
>its reference and bind counters. Implement both action search and check
>using new safe function
>
>Reference taken by idr check is temporal and should not be accounted by
>userspace clients (both logically and to preserver current API behavior).
>Subtract temporal reference when dumping action to userspace using existing
>tca_get_fill function arguments.
>
>Signed-off-by: Vlad Buslov <vladbu@...lanox.com>

Signed-off-by: Jiri Pirko <jiri@...lanox.com>