linux-kernel - Re: [PATCH net-next] net: add in_softirq() debug checking in napi_consume

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

Date:   Wed, 18 Nov 2020 16:57:57 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Yunsheng Lin <linyunsheng@...wei.com>, davem@...emloft.net,
        linmiaohe@...wei.com, martin.varghese@...ia.com, pabeni@...hat.com,
        pshelar@....org, fw@...len.de, gnault@...hat.com,
        steffen.klassert@...unet.com, kyk.segfault@...il.com,
        viro@...iv.linux.org.uk, vladimir.oltean@....com,
        edumazet@...gle.com, saeed@...nel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linuxarm@...wei.com
Subject: Re: [PATCH net-next] net: add in_softirq() debug checking in
 napi_consume_skb()

On Wed, Nov 18, 2020 at 07:43:48AM -0800, Jakub Kicinski wrote:

> TBH the last sentence I wrote isn't clear even to me at this point ;D
> 
> Maybe using just the macros from preempt.h - like this?
> 
> #define lockdep_assert_in_softirq()                                    \
> do {                                                                   \
>        WARN_ON_ONCE(__lockdep_enabled                  &&              \
>                     (!in_softirq() || in_irq() || in_nmi())	\
> } while (0)
> 
> We know what we're doing so in_softirq() should be fine (famous last
> words).

So that's not actually using any lockdep state. But if that's what you
need, I don't have any real complaints.