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[188.85.150.151]) by smtp.gmail.com with ESMTPSA id z9-20020a7bc7c9000000b004060f0a0fd5sm1745935wmk.13.2023.10.04.08.09.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Oct 2023 08:09:59 -0700 (PDT) From: Juan Quintela To: Markus Armbruster Cc: qemu-devel@nongnu.org, peterx@redhat.com, leobras@redhat.com, farosas@suse.de, lizhijian@fujitsu.com, eblake@redhat.com Subject: Re: [PATCH v2 18/53] migration/rdma: Fix io_writev(), io_readv() methods to obey contract In-Reply-To: <20230928132019.2544702-19-armbru@redhat.com> (Markus Armbruster's message of "Thu, 28 Sep 2023 15:19:44 +0200") References: <20230928132019.2544702-1-armbru@redhat.com> <20230928132019.2544702-19-armbru@redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.3 (gnu/linux) Date: Wed, 04 Oct 2023 17:09:58 +0200 Message-ID: <87cyxuxw3d.fsf@secure.mitica> MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=170.10.129.124; envelope-from=quintela@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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: , Reply-To: quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Markus Armbruster wrote: > QIOChannelClass methods qio_channel_rdma_readv() and > qio_channel_rdma_writev() violate their method contract when > rdma->error_state is non-zero: > > 1. They return whatever is in rdma->error_state then. Only -1 will be > fine. -2 will be misinterpreted as "would block". Anything less > than -2 isn't defined in the contract. A positive value would be > misinterpreted as success, but I believe that's not actually > possible. > > 2. They neglect to set an error then. If something up the call stack > dereferences the error when failure is returned, it will crash. If > it ignores the return value and checks the error instead, it will > miss the error. > > Crap like this happens when return statements hide in macros, > especially when their uses are far away from the definition. > > I elected not to investigate how callers are impacted. > > Expand the two bad macro uses, so we can set an error and return -1. > The next commit will then get rid of the macro altogether. > > Signed-off-by: Markus Armbruster > Reviewed-by: Fabiano Rosas > Reviewed-by: Li Zhijian Reviewed-by: Juan Quintela