695c12147a
Prepare for having multi-prog attachments for new netns attach types by storing programs to run in a bpf_prog_array, which is well suited for iterating over programs and running them in sequence. After this change bpf(PROG_QUERY) may block to allocate memory in bpf_prog_array_copy_to_user() for collected program IDs. This forces a change in how we protect access to the attached program in the query callback. Because bpf_prog_array_copy_to_user() can sleep, we switch from an RCU read lock to holding a mutex that serializes updaters. Because we allow only one BPF flow_dissector program to be attached to netns at all times, the bpf_prog_array pointed by net->bpf.run_array is always either detached (null) or one element long. No functional changes intended. Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200625141357.910330-3-jakub@cloudflare.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.