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Fri, 30 Sep 2022 06:32:50 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id +Ja0BpKNNmOlFAAAMHmgww (envelope-from ); Fri, 30 Sep 2022 06:32:50 +0000 Message-ID: <5506f1d3-3f46-9be4-ae22-66bbc4f053bd@suse.de> Date: Fri, 30 Sep 2022 08:32:49 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [PATCH v2] nvmet: force reconnect when number of queue changes Content-Language: en-US To: "Knight, Frederick" , Daniel Wagner , John Meneghini Cc: Sagi Grimberg , "linux-nvme@lists.infradead.org" , Shinichiro Kawasaki References: <20220927143157.3659-1-dwagner@suse.de> <20220928074850.h6rwvwgz2oje3ebg@carbon.lan> <20220928090243.c4ctbj2frydwsfav@carbon.lan> <6e172046-53e7-d2cb-38b8-e87d725046de@redhat.com> <20220928152616.inzetc3fsvnhb3o5@carbon.lan> From: Hannes Reinecke In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220929_233252_546400_9586F508 X-CRM114-Status: GOOD ( 16.10 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 9/28/22 20:02, Knight, Frederick wrote: > Reset and Disconnect are different. > > Reset uses registers (and therefore Get Property and Set Property commands) over a valid connection. > > Disconnect causes a reset (you have to reconnect to the reset controller) > Reset does not cause an immediate disconnect. > This probably is a confusion with how the linux implementation works. For linux NVMe-oF a reset is equivalent to a reconnect (ie disconnect followed by a reconnect), as for linux _any_ error will be escalated to be equivalent to a connection error. Hence a pure 'reset' using Get/Set Property is never attempted. Cheers, Hannes >> -----Original Message----- >> From: Daniel Wagner >> Sent: Wednesday, September 28, 2022 11:26 AM >> To: John Meneghini >> Cc: Knight, Frederick ; Sagi Grimberg >> ; linux-nvme@lists.infradead.org; Shinichiro Kawasaki >> ; hare@suse.de >> Subject: Re: [PATCH v2] nvmet: force reconnect when number of queue >> changes >> >> NetApp Security WARNING: This is an external email. Do not click links or >> open attachments unless you recognize the sender and know the content is >> safe. >> >> >> >> >> On Wed, Sep 28, 2022 at 11:01:00AM -0400, John Meneghini wrote: >>> So this is one place where I think we conflate NVMe-oF with NVMe in >>> the specification. If "reset" == "disconnect", then Daniel's patches >>> just implemented support for something which is forbidden by the spec >>> - a controller that changes the number of IOQs between resets. >> >> FWIW, the scenario I described is from a real world experience. So even if it >> is forbidden by the spec, it exists. -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Ivo Totev, Andrew Myers, Andrew McDonald, Martje Boudien Moerman