bb5a93aaf2
Using a mutex for "print this warning only once" is so overdesigned as to be actively offensive to my sensitive stomach. Just use "pr_info_once()" that already does this, although in a (harmlessly) racy manner that can in theory cause the message to be printed twice if more than one CPU races on that "is this the first time" test. [ If somebody really cares about that harmless data race (which sounds very unlikely indeed), that person can trivially fix printk_once() by using a simple atomic access, preferably with an optimistic non-atomic test first before even bothering to treat the pointless "make sure it is _really_ just once" case. A mutex is most definitely never the right primitive to use for something like this. ] Yes, this is a small and meaningless detail in a code path that hardly matters. But let's keep some code quality standards here, and not accept outrageously bad code. Link: https://lore.kernel.org/lkml/CAHk-=wgV9toS7GU3KmNpj8hCS9SeF+A0voHS8F275_mgLhL4Lw@mail.gmail.com/ Cc: Andy Lutomirski <luto@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> 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.