netdev - Re: [PATCH net] net: sched: flower: don't call synchronize

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <20190614.193047.261788013564267611.davem@davemloft.net>
Date:   Fri, 14 Jun 2019 19:30:47 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     vladbu@...lanox.com
Cc:     netdev@...r.kernel.org, jhs@...atatu.com, xiyou.wangcong@...il.com,
        jiri@...nulli.us, pablo@...filter.org, alexanderk@...lanox.com,
        pabeni@...hat.com, mlxsw@...lanox.com, jiri@...lanox.com
Subject: Re: [PATCH net] net: sched: flower: don't call synchronize_rcu()
 on mask creation

From: Vlad Buslov <vladbu@...lanox.com>
Date: Thu, 13 Jun 2019 17:54:04 +0300

> Current flower mask creating code assumes that temporary mask that is used
> when inserting new filter is stack allocated. To prevent race condition
> with data patch synchronize_rcu() is called every time fl_create_new_mask()
> replaces temporary stack allocated mask. As reported by Jiri, this
> increases runtime of creating 20000 flower classifiers from 4 seconds to
> 163 seconds. However, this design is no longer necessary since temporary
> mask was converted to be dynamically allocated by commit 2cddd2014782
> ("net/sched: cls_flower: allocate mask dynamically in fl_change()").
> 
> Remove synchronize_rcu() calls from mask creation code. Instead, refactor
> fl_change() to always deallocate temporary mask with rcu grace period.
> 
> Fixes: 195c234d15c9 ("net: sched: flower: handle concurrent mask insertion")
> Reported-by: Jiri Pirko <jiri@...lanox.com>
> Signed-off-by: Vlad Buslov <vladbu@...lanox.com>

Applied, thanks.