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... and produce consistent error on attempt to delete such. Existing check in u32_delete() is inconsistent - after tc qdisc add dev eth0 ingress tc filter add dev eth0 parent ffff: protocol ip prio 100 handle 1: u32 \ divisor 1 tc filter add dev eth0 parent ffff: protocol ip prio 200 handle 2: u32 \ divisor 1 both tc filter delete dev eth0 parent ffff: protocol ip prio 100 handle 801: u32 and tc filter delete dev eth0 parent ffff: protocol ip prio 100 handle 800: u32 will fail (at least with refcounting fixes), but the former will complain about an attempt to remove a busy table, while the latter will recognize it as root and yield "Not allowed to delete root node" instead. The problem with the existing check is that several tcf_proto instances might share the same tp->data and handle-to-hnode lookup will be the same for all of them. So comparing an hnode to be deleted with tp->root won't catch the case when one tp is used to try deleting the root of another. Solution is trivial - mark the root hnodes explicitly upon allocation and check for that. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.