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[142.68.57.212]) by smtp.gmail.com with ESMTPSA id m1sm2571690qtm.22.2020.03.26.15.36.04 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 26 Mar 2020 15:36:04 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1jHb6a-0003Z0-7r; Thu, 26 Mar 2020 19:36:04 -0300 Date: Thu, 26 Mar 2020 19:36:04 -0300 From: Jason Gunthorpe To: Wei Yang Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] mm/page_alloc.c: leverage compiler to zero out used_mask Message-ID: <20200326223604.GP20941@ziepe.ca> References: <20200326222445.18781-1-richard.weiyang@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200326222445.18781-1-richard.weiyang@gmail.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Mar 26, 2020 at 10:24:44PM +0000, Wei Yang wrote: > Since we always clear used_mask before getting node order, we can > leverage compiler to do this instead of at run time. > > Signed-off-by: Wei Yang > mm/page_alloc.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 0e823bca3f2f..2144b6ceb119 100644 > +++ b/mm/page_alloc.c > @@ -5587,14 +5587,13 @@ static void build_zonelists(pg_data_t *pgdat) > { > static int node_order[MAX_NUMNODES]; > int node, load, nr_nodes = 0; > - nodemask_t used_mask; > + nodemask_t used_mask = {.bits = {0}}; If this style is to be done it should just be '= {}'; This case demonstrates why the popular '= {0}' idiom is not such a good idea, as it only works if the first member is an integral type. Jason