linux-kernel - Re: [PATCH 01/31] rhashtable: Allow rhashtable to be used from irq-safe contexts

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]

Message-ID: <CAHk-=wg8wvB4vo-PaCSMSRaCd2c+rk8OnE72eF+skDVMdk9LsA@mail.gmail.com>
Date:   Wed, 30 Nov 2022 08:35:13 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Tejun Heo <tj@...nel.org>
Cc:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com, ast@...nel.org,
        daniel@...earbox.net, andrii@...nel.org, martin.lau@...nel.org,
        joshdon@...gle.com, brho@...gle.com, pjt@...gle.com,
        derkling@...gle.com, haoluo@...gle.com, dvernet@...a.com,
        dschatzberg@...a.com, dskarlat@...cmu.edu, riel@...riel.com,
        linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
        kernel-team@...a.com
Subject: Re: [PATCH 01/31] rhashtable: Allow rhashtable to be used from
 irq-safe contexts

On Wed, Nov 30, 2022 at 12:23 AM Tejun Heo <tj@...nel.org> wrote:
>
>
>  static inline void rht_lock(struct bucket_table *tbl,
> -                           struct rhash_lock_head __rcu **bkt)
> +                           struct rhash_lock_head __rcu **bkt,
> +                           unsigned long *flags)

I guess it doesn't matter as long as this actually gets inlined, but
wouldn't it be better to have

   flags = rht_lock(..);
   ...
   rht_unlock(.., flags);

as the calling convention? Rather than passing a pointer to the stack around.

That's what the native _raw_spin_lock_irqsave() interface is (even if
"spin_lock_irqsave()" itself for historical reasons uses that inline
asm-like "pass argument by reference *without* using a pointer")

And gaah, we should have made 'flags' be a real type long ago, but I
guess 'unsigned long' is too ingrained and traditional to change that
now.

              Linus