From: Bart Van Assche <bvanassche@acm.org>
To: Jinpu Wang <jinpu.wang@cloud.ionos.com>
Cc: Jack Wang <jinpuwang@gmail.com>,
linux-block@vger.kernel.org, linux-rdma@vger.kernel.org,
Jens Axboe <axboe@kernel.dk>,
Christoph Hellwig <hch@infradead.org>,
Sagi Grimberg <sagi@grimberg.me>,
Leon Romanovsky <leon@kernel.org>,
Doug Ledford <dledford@redhat.com>,
Danil Kipnis <danil.kipnis@cloud.ionos.com>,
rpenyaev@suse.de
Subject: Re: [PATCH v6 03/25] rtrs: private headers with rtrs protocol structs and helpers
Date: Thu, 2 Jan 2020 09:00:53 -0800 [thread overview]
Message-ID: <51f2aec2-db24-ce7b-b3e8-68f9561a584b@acm.org> (raw)
In-Reply-To: <CAMGffEmC3T9M+RmeOXX4ecE3E01azjD8fz2Lz8kHC9Ff-Xx-Aw@mail.gmail.com>
On 1/2/20 7:27 AM, Jinpu Wang wrote:
> On Mon, Dec 30, 2019 at 8:48 PM Bart Van Assche <bvanassche@acm.org> wrote:
>> On 2019-12-30 02:29, Jack Wang wrote:
>>> +enum {
>>> + SERVICE_CON_QUEUE_DEPTH = 512,
>>
>> What is a service connection?
> s/SERVICE_CON_QUEUE_DEPTH/CON_QUEUE_DEPTH/g, do you think
> CON_QUEUE_DEPTH is better or just QUEUE_DEPTH?
The name of the constant is fine, but what I meant is the following: has
it been documented anywhere what the role of a "service connection" is?
>>> +struct rtrs_ib_dev_pool {
>>> + struct mutex mutex;
>>> + struct list_head list;
>>> + enum ib_pd_flags pd_flags;
>>> + const struct rtrs_ib_dev_pool_ops *ops;
>>> +};
>>
>> What is the purpose of an rtrs_ib_dev_pool and what does it contain?
> The idea was documented in the patchset here:
> https://www.spinics.net/lists/linux-rdma/msg64025.html
> "'
> This is an attempt to make a device pool API out of a common code,
> which caches pair of ib_device and ib_pd pointers. I found 4 places,
> where this common functionality can be replaced by some lib calls:
> nvme, nvmet, iser and isert. Total deduplication gain in loc is not
> quite significant, but eventually new ULP IB code can also require
> the same device/pd pair cache, e.g. in our IBTRS module the same
> code has to be repeated again, which was observed by Sagi and he
> suggested to make a common helper function instead of producing
> another copy.
> '''
The word "pool" suggest ownership. Since struct rtrs_ib_dev_pool owns
protection domains instead of RDMA devices, how about renaming that data
structure into rtrs_pd_per_rdma_dev, rtrs_rdma_dev_pd or something
similar? How about adding a comment like the following above that data
structure?
/*
* Data structure used to associate one protection domain (PD) with each
* RDMA device.
*/
>>> +/**
>>> + * struct rtrs_msg_conn_req - Client connection request to the server
>>> + * @magic: RTRS magic
>>> + * @version: RTRS protocol version
>>> + * @cid: Current connection id
>>> + * @cid_num: Number of connections per session
>>> + * @recon_cnt: Reconnections counter
>>> + * @sess_uuid: UUID of a session (path)
>>> + * @paths_uuid: UUID of a group of sessions (paths)
>>> + *
>>> + * NOTE: max size 56 bytes, see man rdma_connect().
>>> + */
>>> +struct rtrs_msg_conn_req {
>>> + u8 __cma_version; /* Is set to 0 by cma.c in case of
>>> + * AF_IB, do not touch that.
>>> + */
>>> + u8 __ip_version; /* On sender side that should be
>>> + * set to 0, or cma_save_ip_info()
>>> + * extract garbage and will fail.
>>> + */
>>
>> The above two fields and the comments next to it look suspicious to me.
>> Does RTRS perhaps try to generate CMA-formatted messages without using
>> the CMA to format these messages?
> The problem is in cma_format_hdr over-writes the first byte for AF_IB
> https://www.spinics.net/lists/linux-rdma/msg22397.html
>
> No one fixes the problem since then.
How about adding that URL to the comment block above struct
rtrs_msg_conn_req?
>>
>>> + *errno = -(int)((payload >> 19) & 0x1ff);
>>
>> Is the '(int)' cast useful in the above expression? Can it be left out?
> I think it's necessary, and make it more clear errno is a negative int
> value, isn't it?
According to the C standard operations on unsigned integers "wrap
around" so removing the cast should be safe. Anyway, this is not
something I consider important.
Thanks,
Bart.
next prev parent reply other threads:[~2020-01-02 17:00 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-30 10:29 [PATCH v6 00/25] RTRS (former IBTRS) rdma transport library and RNBD (former IBNBD) rdma network block device Jack Wang
2019-12-30 10:29 ` [PATCH v6 01/25] sysfs: export sysfs_remove_file_self() Jack Wang
2019-12-30 10:29 ` [PATCH v6 02/25] rtrs: public interface header to establish RDMA connections Jack Wang
2019-12-30 19:25 ` Bart Van Assche
2020-01-02 13:35 ` Jinpu Wang
2020-01-02 16:36 ` Bart Van Assche
2020-01-02 16:47 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 03/25] rtrs: private headers with rtrs protocol structs and helpers Jack Wang
2019-12-30 19:48 ` Bart Van Assche
2020-01-02 15:27 ` Jinpu Wang
2020-01-02 17:00 ` Bart Van Assche [this message]
2020-01-02 18:26 ` Jason Gunthorpe
2020-01-03 12:31 ` Jinpu Wang
2020-01-03 12:27 ` Jinpu Wang
2019-12-31 0:07 ` Bart Van Assche
2020-01-03 13:48 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 04/25] rtrs: core: lib functions shared between client and server modules Jack Wang
2019-12-30 22:25 ` Bart Van Assche
2020-01-07 12:22 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 05/25] rtrs: client: private header with client structs and functions Jack Wang
2019-12-30 22:51 ` Bart Van Assche
2020-01-07 12:39 ` Jinpu Wang
2019-12-30 23:03 ` Bart Van Assche
2020-01-07 12:39 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 06/25] rtrs: client: main functionality Jack Wang
2019-12-30 23:53 ` Bart Van Assche
2020-01-02 18:23 ` Jason Gunthorpe
2020-01-03 14:30 ` Jinpu Wang
2020-01-03 16:12 ` Bart Van Assche
2019-12-30 10:29 ` [PATCH v6 07/25] rtrs: client: statistics functions Jack Wang
2020-01-02 21:07 ` Bart Van Assche
2020-01-03 14:39 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 08/25] rtrs: client: sysfs interface functions Jack Wang
2020-01-02 21:14 ` Bart Van Assche
2020-01-03 14:59 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 09/25] rtrs: server: private header with server structs and functions Jack Wang
2020-01-02 21:24 ` Bart Van Assche
2020-01-08 16:33 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 10/25] rtrs: server: main functionality Jack Wang
2020-01-02 22:03 ` Bart Van Assche
2020-01-07 13:19 ` Jinpu Wang
2020-01-07 18:25 ` Jason Gunthorpe
2020-01-10 17:38 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 11/25] rtrs: server: statistics functions Jack Wang
2020-01-02 22:02 ` Bart Van Assche
2020-01-08 12:55 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 12/25] rtrs: server: sysfs interface functions Jack Wang
2020-01-02 22:06 ` Bart Van Assche
2020-01-07 14:40 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 13/25] rtrs: include client and server modules into kernel compilation Jack Wang
2020-01-02 22:11 ` Bart Van Assche
2020-01-03 16:19 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 14/25] rtrs: a bit of documentation Jack Wang
2019-12-30 23:19 ` Bart Van Assche
2020-01-07 14:48 ` Jinpu Wang
2020-01-02 22:21 ` Bart Van Assche
2020-01-07 15:49 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 15/25] rnbd: private headers with rnbd protocol structs and helpers Jack Wang
2020-01-02 22:34 ` Bart Van Assche
2020-01-07 16:53 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 16/25] rnbd: client: private header with client structs and functions Jack Wang
2020-01-02 22:37 ` Bart Van Assche
2020-01-07 17:09 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 17/25] rnbd: client: main functionality Jack Wang
2020-01-02 23:55 ` Bart Van Assche
2020-01-08 14:22 ` Jinpu Wang
2020-01-10 14:45 ` Jinpu Wang
2020-01-10 15:09 ` Roman Penyaev
2020-01-10 15:29 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 18/25] rnbd: client: sysfs interface functions Jack Wang
2020-01-03 0:03 ` Bart Van Assche
2020-01-08 13:06 ` Jinpu Wang
2020-01-08 16:39 ` Bart Van Assche
2020-01-08 16:51 ` Jinpu Wang
2019-12-30 10:29 ` [PATCH v6 19/25] rnbd: server: private header with server structs and functions Jack Wang
2019-12-30 10:29 ` [PATCH v6 20/25] rnbd: server: main functionality Jack Wang
2019-12-30 10:29 ` [PATCH v6 21/25] rnbd: server: functionality for IO submission to file or block dev Jack Wang
2019-12-30 10:29 ` [PATCH v6 22/25] rnbd: server: sysfs interface functions Jack Wang
2019-12-30 10:29 ` [PATCH v6 23/25] rnbd: include client and server modules into kernel compilation Jack Wang
2019-12-30 10:29 ` [PATCH v6 24/25] rnbd: a bit of documentation Jack Wang
2019-12-30 10:29 ` [PATCH v6 25/25] MAINTAINERS: Add maintainers for RNBD/RTRS modules Jack Wang
2019-12-30 12:22 ` Gal Pressman
2020-01-02 8:41 ` Jinpu Wang
2019-12-31 0:11 ` [PATCH v6 00/25] RTRS (former IBTRS) rdma transport library and RNBD (former IBNBD) rdma network block device Bart Van Assche
2020-01-02 8:48 ` Jinpu Wang
2019-12-31 2:39 ` Bart Van Assche
2020-01-02 9:20 ` Jinpu Wang
2020-01-02 18:28 ` Jason Gunthorpe
2020-01-03 12:34 ` Jinpu Wang
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