From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-x242.google.com (mail-it0-x242.google.com [IPv6:2607:f8b0:4001:c0b::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 798622111FE43 for ; Wed, 5 Sep 2018 14:18:52 -0700 (PDT) Received: by mail-it0-x242.google.com with SMTP id d10-v6so11929596itj.5 for ; Wed, 05 Sep 2018 14:18:52 -0700 (PDT) Subject: Re: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-8-logang@deltatee.com> <20180901082812.GB670@lst.de> <5f79c012-c6e1-56bb-62fd-0689181fb2c9@deltatee.com> <59b28977-8f2a-6228-2050-03fae6bdbedd@kernel.dk> <1b4283da-44df-4a02-3167-e295243cef78@deltatee.com> <09258b9b-3aed-9890-b31a-bd70a133966c@kernel.dk> <20180905195647.GA1626@lst.de> <20180905201152.GA1893@lst.de> <2a3394bd-5f13-4818-43f4-dfc61f501e05@kernel.dk> <3af4d1d4-da07-c0a6-8464-9ddc1378f2f4@kernel.dk> <34d9b2f7-9e6d-4a0a-77e5-ec0e99610f5c@kernel.dk> From: Jens Axboe Message-ID: <957591a9-3b9d-e730-9919-508349735db9@kernel.dk> Date: Wed, 5 Sep 2018 15:18:48 -0600 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Logan Gunthorpe , Christoph Hellwig Cc: Alex Williamson , linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Jason Gunthorpe , Benjamin Herrenschmidt , Bjorn Helgaas , Max Gurtovoy , =?UTF-8?Q?Christian_K=c3=b6nig?= List-ID: On 9/5/18 3:03 PM, Logan Gunthorpe wrote: > > > On 05/09/18 02:36 PM, Jens Axboe wrote: >> On 9/5/18 2:32 PM, Logan Gunthorpe wrote: >>> >>> >>> On 05/09/18 02:19 PM, Jens Axboe wrote: >>>> On 9/5/18 2:18 PM, Logan Gunthorpe wrote: >>>>> >>>>> >>>>> On 05/09/18 02:14 PM, Jens Axboe wrote: >>>>>> But if the caller must absolutely know where the bio will end up, then >>>>>> it seems super redundant. So I'd vote for killing this check, it buys >>>>>> us absolutely nothing and isn't even exhaustive in its current form. >>>>> >>>>> >>>>> Ok, I'll remove it for v6. >>>> >>>> Since the drivers needs to know it's doing it right, it might not >>>> hurt to add a sanity check helper for that. Just have the driver >>>> call it, and don't add it in the normal IO submission path. >>> >>> I'm not sure I really see the value in that. It's the same principle in >>> asking the driver to do the WARN: if the developer knew enough to use >>> the special helper, they probably knew well enough to do the rest correctly. >> >> I don't agree with that at all. It's a "is my request valid" helper, >> it's not some obscure and rarely used functionality. You're making up >> this API right now, if you really want it done for every IO, make it >> part of the p2p submission process. You could even hide it behind a >> debug thing, if you like. > > There is no special p2p submission process. In the nvme-of case we are > using the existing process and with the code in blk-core it didn't > change it's process at all. Creating a helper will create one and I can > look at making a pci_p2pdma_submit_bio() for v6; but if the developer > screws up and still calls the regular submit_bio() things will only be > very subtly broken and that won't be obvious. I'm very sure that something that basic will be caught in review. I don't care if you wrap the submission or just require the caller to call some validity helper check first, fwiw. And I think we're done beating the dead horse at this point. -- Jens Axboe _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests To: Logan Gunthorpe , Christoph Hellwig Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org, linux-nvdimm@lists.01.org, linux-block@vger.kernel.org, Stephen Bates , Keith Busch , Sagi Grimberg , Bjorn Helgaas , Jason Gunthorpe , Max Gurtovoy , Dan Williams , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Benjamin Herrenschmidt , Alex Williamson , =?UTF-8?Q?Christian_K=c3=b6nig?= References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-8-logang@deltatee.com> <20180901082812.GB670@lst.de> <5f79c012-c6e1-56bb-62fd-0689181fb2c9@deltatee.com> <59b28977-8f2a-6228-2050-03fae6bdbedd@kernel.dk> <1b4283da-44df-4a02-3167-e295243cef78@deltatee.com> <09258b9b-3aed-9890-b31a-bd70a133966c@kernel.dk> <20180905195647.GA1626@lst.de> <20180905201152.GA1893@lst.de> <2a3394bd-5f13-4818-43f4-dfc61f501e05@kernel.dk> <3af4d1d4-da07-c0a6-8464-9ddc1378f2f4@kernel.dk> <34d9b2f7-9e6d-4a0a-77e5-ec0e99610f5c@kernel.dk> From: Jens Axboe Message-ID: <957591a9-3b9d-e730-9919-508349735db9@kernel.dk> Date: Wed, 5 Sep 2018 15:18:48 -0600 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 List-ID: On 9/5/18 3:03 PM, Logan Gunthorpe wrote: > > > On 05/09/18 02:36 PM, Jens Axboe wrote: >> On 9/5/18 2:32 PM, Logan Gunthorpe wrote: >>> >>> >>> On 05/09/18 02:19 PM, Jens Axboe wrote: >>>> On 9/5/18 2:18 PM, Logan Gunthorpe wrote: >>>>> >>>>> >>>>> On 05/09/18 02:14 PM, Jens Axboe wrote: >>>>>> But if the caller must absolutely know where the bio will end up, then >>>>>> it seems super redundant. So I'd vote for killing this check, it buys >>>>>> us absolutely nothing and isn't even exhaustive in its current form. >>>>> >>>>> >>>>> Ok, I'll remove it for v6. >>>> >>>> Since the drivers needs to know it's doing it right, it might not >>>> hurt to add a sanity check helper for that. Just have the driver >>>> call it, and don't add it in the normal IO submission path. >>> >>> I'm not sure I really see the value in that. It's the same principle in >>> asking the driver to do the WARN: if the developer knew enough to use >>> the special helper, they probably knew well enough to do the rest correctly. >> >> I don't agree with that at all. It's a "is my request valid" helper, >> it's not some obscure and rarely used functionality. You're making up >> this API right now, if you really want it done for every IO, make it >> part of the p2p submission process. You could even hide it behind a >> debug thing, if you like. > > There is no special p2p submission process. In the nvme-of case we are > using the existing process and with the code in blk-core it didn't > change it's process at all. Creating a helper will create one and I can > look at making a pci_p2pdma_submit_bio() for v6; but if the developer > screws up and still calls the regular submit_bio() things will only be > very subtly broken and that won't be obvious. I'm very sure that something that basic will be caught in review. I don't care if you wrap the submission or just require the caller to call some validity helper check first, fwiw. And I think we're done beating the dead horse at this point. -- Jens Axboe From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests Date: Wed, 5 Sep 2018 15:18:48 -0600 Message-ID: <957591a9-3b9d-e730-9919-508349735db9@kernel.dk> References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-8-logang@deltatee.com> <20180901082812.GB670@lst.de> <5f79c012-c6e1-56bb-62fd-0689181fb2c9@deltatee.com> <59b28977-8f2a-6228-2050-03fae6bdbedd@kernel.dk> <1b4283da-44df-4a02-3167-e295243cef78@deltatee.com> <09258b9b-3aed-9890-b31a-bd70a133966c@kernel.dk> <20180905195647.GA1626@lst.de> <20180905201152.GA1893@lst.de> <2a3394bd-5f13-4818-43f4-dfc61f501e05@kernel.dk> <3af4d1d4-da07-c0a6-8464-9ddc1378f2f4@kernel.dk> <34d9b2f7-9e6d-4a0a-77e5-ec0e99610f5c@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" To: Logan Gunthorpe , Christoph Hellwig Cc: Alex Williamson , linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-nvme-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Jason Gunthorpe , Benjamin Herrenschmidt , Bjorn Helgaas , Max Gurtovoy , =?UTF-8?Q?Christian_K=c3=b6nig?= List-Id: linux-rdma@vger.kernel.org On 9/5/18 3:03 PM, Logan Gunthorpe wrote: > > > On 05/09/18 02:36 PM, Jens Axboe wrote: >> On 9/5/18 2:32 PM, Logan Gunthorpe wrote: >>> >>> >>> On 05/09/18 02:19 PM, Jens Axboe wrote: >>>> On 9/5/18 2:18 PM, Logan Gunthorpe wrote: >>>>> >>>>> >>>>> On 05/09/18 02:14 PM, Jens Axboe wrote: >>>>>> But if the caller must absolutely know where the bio will end up, then >>>>>> it seems super redundant. So I'd vote for killing this check, it buys >>>>>> us absolutely nothing and isn't even exhaustive in its current form. >>>>> >>>>> >>>>> Ok, I'll remove it for v6. >>>> >>>> Since the drivers needs to know it's doing it right, it might not >>>> hurt to add a sanity check helper for that. Just have the driver >>>> call it, and don't add it in the normal IO submission path. >>> >>> I'm not sure I really see the value in that. It's the same principle in >>> asking the driver to do the WARN: if the developer knew enough to use >>> the special helper, they probably knew well enough to do the rest correctly. >> >> I don't agree with that at all. It's a "is my request valid" helper, >> it's not some obscure and rarely used functionality. You're making up >> this API right now, if you really want it done for every IO, make it >> part of the p2p submission process. You could even hide it behind a >> debug thing, if you like. > > There is no special p2p submission process. In the nvme-of case we are > using the existing process and with the code in blk-core it didn't > change it's process at all. Creating a helper will create one and I can > look at making a pci_p2pdma_submit_bio() for v6; but if the developer > screws up and still calls the regular submit_bio() things will only be > very subtly broken and that won't be obvious. I'm very sure that something that basic will be caught in review. I don't care if you wrap the submission or just require the caller to call some validity helper check first, fwiw. And I think we're done beating the dead horse at this point. -- Jens Axboe From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Subject: Re: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests To: Logan Gunthorpe , Christoph Hellwig References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-8-logang@deltatee.com> <20180901082812.GB670@lst.de> <5f79c012-c6e1-56bb-62fd-0689181fb2c9@deltatee.com> <59b28977-8f2a-6228-2050-03fae6bdbedd@kernel.dk> <1b4283da-44df-4a02-3167-e295243cef78@deltatee.com> <09258b9b-3aed-9890-b31a-bd70a133966c@kernel.dk> <20180905195647.GA1626@lst.de> <20180905201152.GA1893@lst.de> <2a3394bd-5f13-4818-43f4-dfc61f501e05@kernel.dk> <3af4d1d4-da07-c0a6-8464-9ddc1378f2f4@kernel.dk> <34d9b2f7-9e6d-4a0a-77e5-ec0e99610f5c@kernel.dk> From: Jens Axboe Message-ID: <957591a9-3b9d-e730-9919-508349735db9@kernel.dk> Date: Wed, 5 Sep 2018 15:18:48 -0600 MIME-Version: 1.0 In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Keith Busch , Alex Williamson , Sagi Grimberg , linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Stephen Bates , linux-block@vger.kernel.org, =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Jason Gunthorpe , Benjamin Herrenschmidt , Bjorn Helgaas , Max Gurtovoy , Dan Williams , =?UTF-8?Q?Christian_K=c3=b6nig?= Content-Type: text/plain; charset="us-ascii" Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+bjorn=helgaas.com@lists.infradead.org List-ID: On 9/5/18 3:03 PM, Logan Gunthorpe wrote: > > > On 05/09/18 02:36 PM, Jens Axboe wrote: >> On 9/5/18 2:32 PM, Logan Gunthorpe wrote: >>> >>> >>> On 05/09/18 02:19 PM, Jens Axboe wrote: >>>> On 9/5/18 2:18 PM, Logan Gunthorpe wrote: >>>>> >>>>> >>>>> On 05/09/18 02:14 PM, Jens Axboe wrote: >>>>>> But if the caller must absolutely know where the bio will end up, then >>>>>> it seems super redundant. So I'd vote for killing this check, it buys >>>>>> us absolutely nothing and isn't even exhaustive in its current form. >>>>> >>>>> >>>>> Ok, I'll remove it for v6. >>>> >>>> Since the drivers needs to know it's doing it right, it might not >>>> hurt to add a sanity check helper for that. Just have the driver >>>> call it, and don't add it in the normal IO submission path. >>> >>> I'm not sure I really see the value in that. It's the same principle in >>> asking the driver to do the WARN: if the developer knew enough to use >>> the special helper, they probably knew well enough to do the rest correctly. >> >> I don't agree with that at all. It's a "is my request valid" helper, >> it's not some obscure and rarely used functionality. You're making up >> this API right now, if you really want it done for every IO, make it >> part of the p2p submission process. You could even hide it behind a >> debug thing, if you like. > > There is no special p2p submission process. In the nvme-of case we are > using the existing process and with the code in blk-core it didn't > change it's process at all. Creating a helper will create one and I can > look at making a pci_p2pdma_submit_bio() for v6; but if the developer > screws up and still calls the regular submit_bio() things will only be > very subtly broken and that won't be obvious. I'm very sure that something that basic will be caught in review. I don't care if you wrap the submission or just require the caller to call some validity helper check first, fwiw. And I think we're done beating the dead horse at this point. -- Jens Axboe _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme From mboxrd@z Thu Jan 1 00:00:00 1970 From: axboe@kernel.dk (Jens Axboe) Date: Wed, 5 Sep 2018 15:18:48 -0600 Subject: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests In-Reply-To: References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-8-logang@deltatee.com> <20180901082812.GB670@lst.de> <5f79c012-c6e1-56bb-62fd-0689181fb2c9@deltatee.com> <59b28977-8f2a-6228-2050-03fae6bdbedd@kernel.dk> <1b4283da-44df-4a02-3167-e295243cef78@deltatee.com> <09258b9b-3aed-9890-b31a-bd70a133966c@kernel.dk> <20180905195647.GA1626@lst.de> <20180905201152.GA1893@lst.de> <2a3394bd-5f13-4818-43f4-dfc61f501e05@kernel.dk> <3af4d1d4-da07-c0a6-8464-9ddc1378f2f4@kernel.dk> <34d9b2f7-9e6d-4a0a-77e5-ec0e99610f5c@kernel.dk> Message-ID: <957591a9-3b9d-e730-9919-508349735db9@kernel.dk> On 9/5/18 3:03 PM, Logan Gunthorpe wrote: > > > On 05/09/18 02:36 PM, Jens Axboe wrote: >> On 9/5/18 2:32 PM, Logan Gunthorpe wrote: >>> >>> >>> On 05/09/18 02:19 PM, Jens Axboe wrote: >>>> On 9/5/18 2:18 PM, Logan Gunthorpe wrote: >>>>> >>>>> >>>>> On 05/09/18 02:14 PM, Jens Axboe wrote: >>>>>> But if the caller must absolutely know where the bio will end up, then >>>>>> it seems super redundant. So I'd vote for killing this check, it buys >>>>>> us absolutely nothing and isn't even exhaustive in its current form. >>>>> >>>>> >>>>> Ok, I'll remove it for v6. >>>> >>>> Since the drivers needs to know it's doing it right, it might not >>>> hurt to add a sanity check helper for that. Just have the driver >>>> call it, and don't add it in the normal IO submission path. >>> >>> I'm not sure I really see the value in that. It's the same principle in >>> asking the driver to do the WARN: if the developer knew enough to use >>> the special helper, they probably knew well enough to do the rest correctly. >> >> I don't agree with that at all. It's a "is my request valid" helper, >> it's not some obscure and rarely used functionality. You're making up >> this API right now, if you really want it done for every IO, make it >> part of the p2p submission process. You could even hide it behind a >> debug thing, if you like. > > There is no special p2p submission process. In the nvme-of case we are > using the existing process and with the code in blk-core it didn't > change it's process at all. Creating a helper will create one and I can > look at making a pci_p2pdma_submit_bio() for v6; but if the developer > screws up and still calls the regular submit_bio() things will only be > very subtly broken and that won't be obvious. I'm very sure that something that basic will be caught in review. I don't care if you wrap the submission or just require the caller to call some validity helper check first, fwiw. And I think we're done beating the dead horse at this point. -- Jens Axboe