29e95a4b26
Prevent a race vs. statically initialized objects. Such objects are usually not initialized via an init() function. They are special cased and detected on first use under the assumption that they are already correctly initialized via the static initializer. This works correctly unless there are two concurrent debug object operations on such an object. The first one detects that the object is not yet tracked and tries to establish a tracking object after dropping the debug objects hash bucket lock. The concurrent operation does the same. The one which wins the race ends up modifying the state of the object which makes the other one fail resulting in a bogus debug objects warning. Prevent this by making the detection of a static object and the allocation of a tracking object atomic under the hash bucket lock. So the first one to acquire the hash bucket lock will succeed and the second one will observe the correct tracking state. This race existed forever but was only exposed when the timer wheel code added a debug_object_assert_init() call outside of the timer base locked region. This replaced the previous warning about timer::function being NULL which had to be removed when the timer_shutdown() mechanics were added. -----BEGIN PGP SIGNATURE----- iQJHBAABCgAxFiEEQp8+kY+LLUocC4bMphj1TA10mKEFAmRGfx8THHRnbHhAbGlu dXRyb25peC5kZQAKCRCmGPVMDXSYod4YD/98pgjxl9zht0tJpjOQv1GHQeKWGOnS T2NcK7UBF7IZnGVCaQovs1TLPEiHZMY9TgSmefP9UuYNCUthdzgxUv1hljb915zI xcQmqFopUyFF+F+qE7ti1C4HvXzbdss14XK97EcsoooS1ALq5xTkUJEcmdLFRL85 /ACkHz0/iMEHT9QVX6WoAOptg7HLoscb30CEZGa8skStAIRZfMIFqmN5GXzKUsPH oLUldSjoXyqq2ZBu9jiO9GoPmei3VuaZO3qWtN4KYY0C37BvKavgS2N/NsOh7s+0 I51G5+R8o6kQgr3RSll6frsPcy1EXsgPDZXO5tC1W9bp6+yrQ97ztdG0QS52fcPb fcCQtAX3L+K38vf4GfvboDyf7x21leJSYE3u+HCXUlyC2Es8QZgWw4U7Bi8IwSZg /BKC6QkQD/YyG/aQyZq6ZGiLgbJt8g53WiR8HGx35P3RUEy5Mit3bBSuq1dSuGR0 RozFlWswUif3Teticq33MR6Mv9M3866lX4iTMGT50xjJZirb8ongpKkRxIOHVeXV 4//0V/GOswyTwkY884Q6zJCZZq2FEudn6/Vtjh97zLxvJzLbdIEnEPC5HG75Jed0 a9NISg+NT9VOx4PLwgMWgW6dlT5SNUeWD4ddC879c4ELbyNd1i4AY54pMrcwEVVj fGdL6pFfFzZI5w== =19cg -----END PGP SIGNATURE----- Merge tag 'core-debugobjects-2023-04-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull core debugobjects update from Thomas Gleixner: "A single update to debugobjects: Prevent a race vs statically initialized objects. Such objects are usually not initialized via an init() function. They are special cased and detected on first use under the assumption that they are already correctly initialized via the static initializer. This works correctly unless there are two concurrent debug object operations on such an object. The first one detects that the object is not yet tracked and tries to establish a tracking object after dropping the debug objects hash bucket lock. The concurrent operation does the same. The one which wins the race ends up modifying the state of the object which makes the other one fail resulting in a bogus debug objects warning. Prevent this by making the detection of a static object and the allocation of a tracking object atomic under the hash bucket lock. So the first one to acquire the hash bucket lock will succeed and the second one will observe the correct tracking state. This race existed forever but was only exposed when the timer wheel code added a debug_object_assert_init() call outside of the timer base locked region. This replaced the previous warning about timer::function being NULL which had to be removed when the timer_shutdown() mechanics were added" * tag 'core-debugobjects-2023-04-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: debugobject: Prevent init race with static objects |
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| lib | ||
| LICENSES | ||
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| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| README | ||
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.