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The 'filter_cnt' counter is used to control a Qdisc class lifetime. Each filter referecing this class by its id will eventually increment/decrement this counter in their respective 'add/update/delete' routines. As these operations are always serialized under rtnl lock, we don't need an atomic type like 'refcount_t'. It also means that we lose the overflow/underflow checks already present in refcount_t, which are valuable to hunt down bugs where the unsigned counter wraps around as it aids automated tools like syzkaller to scream in such situations. Wrap the open coded increment/decrement into helper functions and add overflow checks to the operations. Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: Pedro Tammela <pctammela@mojatatu.com> Reviewed-by: Simon Horman <horms@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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.