[PATCH v1 0/1] [SRU][F:linux-bluefield][PATCH 1/1] UBUNTU: SAUCE: Fix the rshim logging buffer full/wraparound issue

[Liming Sun]

Buglink: https://bugs.launchpad.net/bugs/1919847

SRU Justification:

[Impact]
* When 'cat /dev/rshim0/misc' with DISPLAY_LEVEL set to 2, the logging
  buffer could be potentially displayed as empty when it's full.

[Fix]
* Add the check properly to make sure the buffer won't wrap-around.

[Test Case]
* Run "bfrshlog <some-message>" repeatedly and check the
  /dev/rshim0/misc with DISPLAY_LEVEL set to 2 in this file. The
  buffer shouldn't be overwritten or wrap-around.

[Regression Potential]
* Yes, it should be easy to add regression by using the bfrshlog to
  add logs on BlueField side, and check the logging buffer 
  (/dev/rshim0/misc) from external rshim host.

[Other]
* N/A