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: <1688668070-8408-1-git-send-email-quic_pintu@quicinc.com>
 <1688668414-12350-1-git-send-email-quic_pintu@quicinc.com>
 <26816f0a-7f55-f5ce-b71d-769011f9230f@arm.com> <ZKgJIlqZk8cw4MBa@casper.infradead.org>
In-Reply-To: <ZKgJIlqZk8cw4MBa@casper.infradead.org>
From:   Pintu Agarwal <pintu.ping@gmail.com>
Date:   Fri, 7 Jul 2023 19:36:20 +0530
Message-ID: <CAOuPNLiOO_Pa=J_-0RhDBQ0auL0rgCjmpCZHtH3ngv6D1OhW6Q@mail.gmail.com>
Subject: Re: [PATCH v2] mm: cma: print cma name as well in cma_alloc debug
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Anshuman Khandual <anshuman.khandual@arm.com>,
        Pintu Kumar <quic_pintu@quicinc.com>,
        linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
        linux-mm@kvack.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Fri, 7 Jul 2023 at 18:16, Matthew Wilcox <willy@infradead.org> wrote:
>
> On Fri, Jul 07, 2023 at 03:57:42PM +0530, Anshuman Khandual wrote:
> > LGTM, cma->name is an identifying attribute for the region for which the allocation
> > request was made. But how about using cma_get_name() helper instead ? Very few call
> > sites have been using the helper.
>
> It's not really a "helper", is it?  The function name is longer than
> its implementation.
>
> cma_get_name(cma)
> vs
> cma->name
>
> Plus there's the usual question about whether a "got" name needs to be
> "put" (does it grab a refcount?)
>
> I think it's useful that this function exists since it lets us not expose
> struct cma outside of mm/, but it really should be called cma_name()
> and I don't think we should be encouraging its use within cma.c.

Also, cma_get_name() is a trivial assignment.
And in one of the previous patches we avoided function calls with
trivial assignments.
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/kernel/dma/contiguous.c?h=next-20230705&id=5af638931eb374aa0894d8343cee72f50307ef20
dma-contiguous: remove dev_set_cma_area

One more question from here:
pr_debug("%s(cma %p, name: %s, count %lu, align %d)\n", __func__,
                (void *)cma, cma->name, count, align);

Do we really need this "cma %p" printing ?
I hardly check it and simply rely on name and count.