mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-03-22 07:27:12 +08:00
1d7f856c2c
While commit83ab38ef0a("jump_label: Fix concurrency issues in static_key_slow_dec()") fixed one problem, it created yet another, notably the following is now possible: slow_dec if (try_dec) // dec_not_one-ish, false // enabled == 1 slow_inc if (inc_not_disabled) // inc_not_zero-ish // enabled == 2 return guard((mutex)(&jump_label_mutex); if (atomic_cmpxchg(1,0)==1) // false, we're 2 slow_dec if (try-dec) // dec_not_one, true // enabled == 1 return else try_dec() // dec_not_one, false WARN Use dec_and_test instead of cmpxchg(), like it was prior to83ab38ef0a. Add a few WARNs for the paranoid. Fixes:83ab38ef0a("jump_label: Fix concurrency issues in static_key_slow_dec()") Reported-by: "Darrick J. Wong" <djwong@kernel.org> Tested-by: Klara Modin <klarasmodin@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.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 reStructuredText 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.