On 1/2/20 7:27 AM, Jinpu Wang wrote:
On Mon, Dec 30, 2019 at 8:48 PM Bart Van Assche <bvanassche@xxxxxxx> 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.
