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([2001:b07:6468:f312:7841:78cc:18c6:1e20]) by smtp.gmail.com with ESMTPSA id s131sm7458669wme.17.2020.08.06.11.41.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 06 Aug 2020 11:41:38 -0700 (PDT) Subject: Re: [RFC 16/16] lpfc: vmid: Introducing vmid in io path. To: Muneendra Kumar M , James Smart , Hannes Reinecke , linux-block@vger.kernel.org, linux-scsi@vger.kernel.org Cc: emilne@redhat.com, mkumar@redhat.com, Gaurav Srivastava , James Smart , Ming Lei , Tejun Heo References: <1596507196-27417-1-git-send-email-muneendra.kumar@broadcom.com> <1596507196-27417-17-git-send-email-muneendra.kumar@broadcom.com> <61d2fd75-84ea-798b-aee9-b07957ac8f1b@suse.de> <08b9825b-6abb-c077-ac0d-bd63f10f2ac2@broadcom.com> <227c5ba1-8a9c-3ec9-5a0f-662a4736c66f@redhat.com> From: Paolo Bonzini Message-ID: Date: Thu, 6 Aug 2020 20:41:36 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 06/08/20 18:26, Muneendra Kumar M wrote: > Hi Paolo, > >> 3.As part of this interface user/deamon will provide the details of VM such >> as UUID,PID on VM creation to the transport . >> The VM process, or the container process, is likely to be unprivileged and >> cannot obtain the permissions needed to do this; therefore, you need to >> cope with the situation where there is no PID yet in the cgroup, because >> the tool >that created the VM or container might be initializing the >> cgroup, but it might not have started the VM yet. In that case there would >> be no PID. > > Agreed.A > small doubt. If the VM is started (running)then we can have the PID and we > can use the PID? Yes, but it's too late when the VM is started. In general there's no requirement that a cgroup is setup shortly before it is populated. >> Would it be possible to pass a file descriptor for the cgroup directory in >> sysfs, instead of the PID? > Yes we can do that. >> Also what would the kernel API look like for this? Would it have to be >> driver-specific? > > The API should be generic and it should not be driver-specific. So it would be a new file in /dev, whose only function is to set up a UUID for a cgroup? Paolo