Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220817162703.728679-1-bigeasy@linutronix.de> <20220817162703.728679-2-bigeasy@linutronix.de>
In-Reply-To: <20220817162703.728679-2-bigeasy@linutronix.de>
From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu, 18 Aug 2022 10:34:28 -0700
Message-ID: <CAHk-=wgCRJx74T0NyRrpWi6XRwy50y8Wzap5XK_3-hN8dbuxTw@mail.gmail.com>
Subject: Re: [PATCH 1/9] slub: Make PREEMPT_RT support less convoluted
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Matthew Wilcox <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Pekka Enberg <penberg@kernel.org>,
        Vlastimil Babka <vbabka@suse.cz>, linux-mm@kvack.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Wed, Aug 17, 2022 at 9:27 AM Sebastian Andrzej Siewior
<bigeasy@linutronix.de> wrote:
>
> The slub code already has a few helpers depending on PREEMPT_RT. Add a few
> more and get rid of the CONFIG_PREEMPT_RT conditionals all over the place.
>
> No functional change.

Looks like a fine cleanup, but I'd prefer that

  #define use_lockless_fast_path()       {(true)/(false)}

to look much less like it's some function call. The first read-through
it looked like some very dynamic thing to me.

Just doing

   #define USE_LOCKLESS_FAST_PATH       ..

would make it much more visually obvious that it's not some kind of
complex run-time decision.

               Linus