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Fri, 14 Aug 2020 08:55:50 -0700 (PDT) Subject: Re: [PATCH v2 1/8] nvme-fabrics: allow to queue requests for live queues To: Christoph Hellwig , Sagi Grimberg References: <20200806191127.592062-1-sagi@grimberg.me> <20200806191127.592062-2-sagi@grimberg.me> <20200814064414.GA1719@lst.de> <27f60468-269a-34d8-9e51-920106c3a139@grimberg.me> <20200814072202.GA2429@lst.de> From: James Smart Message-ID: <4a229e46-c5c4-95f2-2144-b3e2033f404b@broadcom.com> Date: Fri, 14 Aug 2020 08:55:45 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200814072202.GA2429@lst.de> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200814_115555_098450_C7F5BEB9 X-CRM114-Status: GOOD ( 17.75 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Keith Busch , linux-nvme@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 8/14/2020 12:22 AM, Christoph Hellwig wrote: > On Fri, Aug 14, 2020 at 12:08:52AM -0700, Sagi Grimberg wrote: >>> Which will still happen with the admin queue user passthrough >>> commands with this patch, so I don't think it actually solves anything, >>> it just reduces the exposure a bit. >> The original version of the patch removed that as well, but james >> indicated that it's still needed because we have no way to make sure >> the admin (re)connect will be the first request when we unquiesce. > Is that whole thing really a problem? All the pass through requests > are inserted at the head of the queue, so how could something else > slip in before it? If we have a race window we probably need > to use BLK_MQ_REQ_PREEMPT or something like to force executing the > connect on an otherwise frozen queue. It wasn't connect I was worried about - but rather ioctls competing with the ios to init the controller on the admin queue. Had really odd ioctls getting in immediately after connect and before controller enabled. -- james _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme