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Amery Hung says: ==================== This patchset supports struct_ops operators that acquire kptrs through arguments and operators that return a kptr. A coming new struct_ops use case, bpf qdisc [0], has two operators that are not yet supported by current struct_ops infrastructure. Qdisc_ops::enqueue requires getting referenced skb kptr from the argument; Qdisc_ops::dequeue needs to return a referenced skb kptr. This patchset will allow bpf qdisc and other potential struct_ops implementers to do so. For struct_ops implementers: - To get a kptr from an argument, a struct_ops implementer needs to annotate the argument name in the stub function with "__ref" suffix. - The kptr return will automatically work as we now allow operators that return a struct pointer. - The verifier allows returning a null pointer. More control can be added later if there is a future struct_ops implementer only expecting valid pointers. For struct_ops users: - The referenced kptr acquired through the argument needs to be released or xchged into maps just like ones acquired via kfuncs. - To return a referenced kptr in struct_ops, 1) The type of the pointer must matches the return type 2) The pointer must comes from the kernel (not locally allocated), and 3) The pointer must be in its unmodified form [0] https://lore.kernel.org/bpf/20250210174336.2024258-1-ameryhung@gmail.com/ --- v2 - Replace kcalloc+memcpy with kmemdup_array in bpf_prog_ctx_arg_info_init() - Remove unnecessary checks when kfree-ing ctx_arg_info - Remove conditional assignment of ref_obj_id in btf_ctx_access() v1 - Link: https://lore.kernel.org/bpf/20250214164520.1001211-1-ameryhung@gmail.com/ - Fix missing kfree for ctx_arg_info ==================== Link: https://patch.msgid.link/20250217190640.1748177-1-ameryhung@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.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.