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[70.52.229.124]) by smtp.gmail.com with ESMTPSA id y26-20020a05620a0e1a00b0074f4edb7007sm9112437qkm.112.2023.05.04.08.24.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 May 2023 08:24:37 -0700 (PDT) Date: Thu, 4 May 2023 11:24:35 -0400 From: Peter Xu To: Juan Quintela Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Stefan Hajnoczi , Leonardo Bras , Fam Zheng Subject: Re: [PATCH 0/9] QEMU file cleanups Message-ID: References: <20230504113841.23130-1-quintela@redhat.com> <87ttwsp2kx.fsf@secure.mitica> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <87ttwsp2kx.fsf@secure.mitica> Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.161, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, May 04, 2023 at 04:56:46PM +0200, Juan Quintela wrote: > Peter Xu wrote: > > On Thu, May 04, 2023 at 01:38:32PM +0200, Juan Quintela wrote: > >> - convince and review code to see that everything is uint64_t. > > > > One general question to patches regarding this - what's the major benefit > > of using uint64_t? > > > > It doubles the possible numbers to hold, but it's already 64bits so I don't > > think it matters a lot. > > We were checking for negatives even when that can't be. > And we are doing this dance of > > int64_t x, y; > uint64_t a, b; > > x = a; > b = y; > > This is always confusing and not always right. Yeah this is confusing, but if anything can go wrong with this I assume we could have some bigger problem anyway.. > > > The thing is we're removing some code trying to > > detect negative which seems to be still helpful to detect e.g. overflows > > (even though I don't think it'll happen). I just still think it's good to > > know when overflow happens, and not sure what I missed on benefits of using > > unsigned here. > > If you grep through the code, you see that half of the things are > int64_t and the other half is uint64_t. I find it always confusing. Right, I'm personally curious whether we should just use int64_t always unless necessary. :) Another good thing with int64_t is it's also suitable for error report when used in retvals. But no strong opinion here, I don't think that's a huge deal for now. Having such an alignment on types makes sense to me. Thanks, -- Peter Xu