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[156.34.55.100]) by smtp.gmail.com with ESMTPSA id r36sm48135303qte.71.2019.08.06.11.36.05 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 06 Aug 2019 11:36:05 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1hv4JY-0004Lm-Pm; Tue, 06 Aug 2019 15:36:04 -0300 Date: Tue, 6 Aug 2019 15:36:04 -0300 From: Jason Gunthorpe To: Chuhong Yuan Cc: Saeed Mahameed , "linux-kernel@vger.kernel.org" , "davem@davemloft.net" , Tariq Toukan , "linux-rdma@vger.kernel.org" , "netdev@vger.kernel.org" Subject: Re: [PATCH] net/mlx4_core: Use refcount_t for refcount Message-ID: <20190806183604.GQ11627@ziepe.ca> References: <20190802121020.1181-1-hslester96@gmail.com> <47bb83d0111f1132bbf532c16be483c5efbe839f.camel@mellanox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 03, 2019 at 10:42:31AM +0800, Chuhong Yuan wrote: > Saeed Mahameed 于2019年8月3日周六 上午2:38写道： > > > > On Sat, 2019-08-03 at 00:10 +0800, Chuhong Yuan wrote: > > > Chuhong Yuan 于2019年8月2日周五 下午8:10写道： > > > > refcount_t is better for reference counters since its > > > > implementation can prevent overflows. > > > > So convert atomic_t ref counters to refcount_t. > > > > > > > > Also convert refcount from 0-based to 1-based. > > > > > > > > > > It seems that directly converting refcount from 0-based > > > to 1-based is infeasible. > > > I am sorry for this mistake. > > > > Just curious, why not keep it 0 based and use refcout_t ? > > > > refcount API should have the same semantics as atomic_t API .. no ? > > refcount API will warn when increase a 0 refcount. > It regards this as a use-after-free. If this causes failures then the code is not doing atomic as a refcount properly anyhow.. There are some cases where the atomic refcount is just a imprecise debugging aide. Jason