Merge branch 'net-smc-introduce-ringbufs-usage-statistics'

Merge branch 'net-smc-introduce-ringbufs-usage-statistics'

Wen Gu says:

====================
net/smc: introduce ringbufs usage statistics

Currently, we have histograms that show the sizes of ringbufs that ever
used by SMC connections. However, they are always incremental and since
SMC allows the reuse of ringbufs, we cannot know the actual amount of
ringbufs being allocated or actively used.

So this patch set introduces statistics for the amount of ringbufs that
actually allocated by link group and actively used by connections of a
certain net namespace, so that we can react based on these memory usage
information, e.g. active fallback to TCP.

With appropriate adaptations of smc-tools, we can obtain these ringbufs
usage information:

$ smcr -d linkgroup
LG-ID    : 00000500
LG-Role  : SERV
LG-Type  : ASYML
VLAN     : 0
PNET-ID  :
Version  : 1
Conns    : 0
Sndbuf   : 12910592 B    <-
RMB      : 12910592 B    <-

or

$ smcr -d stats
[...]
RX Stats
  Data transmitted (Bytes)      869225943 (869.2M)
  Total requests                 18494479
  Buffer usage  (Bytes)          12910592 (12.31M)  <-
  [...]

TX Stats
  Data transmitted (Bytes)    12760884405 (12.76G)
  Total requests                 36988338
  Buffer usage  (Bytes)          12910592 (12.31M)  <-
  [...]
[...]

Change log:
v3->v2
- use new helper nla_put_uint() instead of nla_put_u64_64bit().

v2->v1
https://lore.kernel.org/r/20240807075939.57882-1-guwen@linux.alibaba.com/
- remove inline keyword in .c files.
- use local variable in macros to avoid potential side effects.

v1
https://lore.kernel.org/r/20240805090551.80786-1-guwen@linux.alibaba.com/
====================

Link: https://patch.msgid.link/20240814130827.73321-1-guwen@linux.alibaba.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>