Waiman Long
51816e9e11
The kernel test robot has reported that the use of __this_cpu_add()
causes bug messages like:
BUG: using __this_cpu_add() in preemptible [00000000] code: ...
Given the imprecise nature of the count and the possibility of resetting
the count and doing the measurement again, this is not really a big
problem to use the unprotected __this_cpu_*() functions.
To make the preemption checking code happy, the this_cpu_*() functions
will be used if CONFIG_DEBUG_PREEMPT is defined.
The imprecise nature of the locking counts are also documented with
the suggestion that we should run the measurement a few times with the
counts reset in between to get a better picture of what is going on
under the hood.
Fixes: a8654596f0 ("locking/rwsem: Enable lock event counting")
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.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.