From: Bart Van Assche <bvanassche@acm.org>
To: Jack Wang <jinpuwang@gmail.com>,
linux-block@vger.kernel.org, linux-rdma@vger.kernel.org
Cc: axboe@kernel.dk, hch@infradead.org, sagi@grimberg.me,
leon@kernel.org, dledford@redhat.com,
danil.kipnis@cloud.ionos.com, jinpu.wang@cloud.ionos.com,
rpenyaev@suse.de
Subject: Re: [PATCH v6 03/25] rtrs: private headers with rtrs protocol structs and helpers
Date: Mon, 30 Dec 2019 11:48:26 -0800 [thread overview]
Message-ID: <b13eccdd-09a2-70d5-1c78-3c4dbf1aefe8@acm.org> (raw)
In-Reply-To: <20191230102942.18395-4-jinpuwang@gmail.com>
On 2019-12-30 02:29, Jack Wang wrote:
> + * InfiniBand Transport Layer
Is RTRS an InfiniBand or an RDMA transport layer?
> +#define rtrs_prefix(obj) (obj->sessname)
Is it really worth it to introduce a macro for accessing a single member
of a single pointer?
> + * InfiniBand Transport Layer
Same question here: is RTRS an InfiniBand or an RDMA transport layer?
> +enum {
> + SERVICE_CON_QUEUE_DEPTH = 512,
What is a service connection?
> + /*
> + * With the current size of the tag allocated on the client, 4K
> + * is the maximum number of tags we can allocate. This number is
> + * also used on the client to allocate the IU for the user connection
> + * to receive the RDMA addresses from the server.
> + */
What does the word 'tag' mean in the context of the RTRS protocol?
> +struct rtrs_ib_dev;
What does the "rtrs_ib_dev" data structure represent? Additionally, I
think it's confusing that a single name has an "r" that refers to "RDMA"
and "ib" that refers to InfiniBand.
> +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?
> +struct rtrs_iu {
A comment that explains what the "iu" abbreviation stands for would be
welcome.
> +/**
> + * enum rtrs_msg_types - RTRS message types.
> + * @RTRS_MSG_INFO_REQ: Client additional info request to the server
> + * @RTRS_MSG_INFO_RSP: Server additional info response to the client
> + * @RTRS_MSG_WRITE: Client writes data per RDMA to server
> + * @RTRS_MSG_READ: Client requests data transfer from server
> + * @RTRS_MSG_RKEY_RSP: Server refreshed rkey for rbuf
> + */
What is "additional info" in this context?
> +/**
> + * 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?
> + u8 reserved[12];
Please leave out the reserved data. If future versions of the protocol
would need any of these bytes it is easy to add more data to this structure.
> +/**
> + * struct rtrs_msg_conn_rsp - Server connection response to the client
> + * @magic: RTRS magic
> + * @version: RTRS protocol version
> + * @errno: If rdma_accept() then 0, if rdma_reject() indicates error
> + * @queue_depth: max inflight messages (queue-depth) in this session
> + * @max_io_size: max io size server supports
> + * @max_hdr_size: max msg header size server supports
> + *
> + * NOTE: size is 56 bytes, max possible is 136 bytes, see man rdma_accept().
> + */
> +struct rtrs_msg_conn_rsp {
> + __le16 magic;
> + __le16 version;
> + __le16 errno;
> + __le16 queue_depth;
> + __le32 max_io_size;
> + __le32 max_hdr_size;
> + __le32 flags;
> + u8 reserved[36];
> +};
Same comment here: please leave out the "reserved[]" array. Sending a
bunch of zero-bytes at the end of a message over the wire is not useful.
> +static inline void rtrs_from_imm(u32 imm, u32 *type, u32 *payload)
> +{
> + *payload = (imm & MAX_IMM_PAYL_MASK);
> + *type = (imm >> MAX_IMM_PAYL_BITS);
> +}
Please do not use parentheses when not necessary. Such superfluous
parentheses namely hurt readability of the code.
> + type = (w_inval ? RTRS_IO_RSP_W_INV_IMM : RTRS_IO_RSP_IMM);
Same comment here: I think the parentheses can be left out from the
above statement.
> +static inline void rtrs_from_io_rsp_imm(u32 payload, u32 *msg_id, int *errno)
> +{
> + /* 9 bits for errno, 19 bits for msg_id */
> + *msg_id = (payload & 0x7ffff);
Are the parentheses in the above expression necessary?
> + *errno = -(int)((payload >> 19) & 0x1ff);
Is the '(int)' cast useful in the above expression? Can it be left out?
> +#define STAT_ATTR(type, stat, print, reset) \
> +STAT_STORE_FUNC(type, stat, reset) \
> +STAT_SHOW_FUNC(type, stat, print) \
> +static struct kobj_attribute stat##_attr = \
> + __ATTR(stat, 0644, \
> + stat##_show, \
> + stat##_store)
Is the above use of __ATTR() perhaps an open-coded version of __ATTR_RW()?
Thanks,
Bart.
next prev parent reply other threads:[~2019-12-30 19:48 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 [this message]
2020-01-02 15:27 ` Jinpu Wang
2020-01-02 17:00 ` Bart Van Assche
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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