f054ffeeb0
[ Upstream commit 257310e998700e60382fbd3f4fd275fdbd9b2aaf ]
Simplify stats accumulation logic to fix the case where we don't take
previous stat value into account, we should always respect it.
Main netdev stats of our PF (Tx/Rx packets/bytes) were reported orders of
magnitude too big during OpenStack reconfiguration events, possibly other
reconfiguration cases too.
The regression was reported to be between 6.1 and 6.2, so I was almost
certain that on of the two "preserve stats over reset" commits were the
culprit. While reading the code, it was found that in some cases we will
increase the stats by arbitrarily large number (thanks to ignoring "-prev"
part of condition, after zeroing it).
Note that this fixes also the case where we were around limits of u64, but
that was not the regression reported.
Full disclosure: I remember suggesting this particular piece of code to
Ben a few years ago, so blame on me.
Fixes: 2fd5e433cd26 ("ice: Accumulate HW and Netdev statistics over reset")
Reported-by: Nebojsa Stevanovic <nebojsa.stevanovic@gcore.com>
Link: https://lore.kernel.org/intel-wired-lan/VI1PR02MB439744DEDAA7B59B9A2833FE912EA@VI1PR02MB4397.eurprd02.prod.outlook.com
Reported-by: Christian Rohmann <christian.rohmann@inovex.de>
Link: https://lore.kernel.org/intel-wired-lan/f38a6ca4-af05-48b1-a3e6-17ef2054e525@inovex.de
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.