From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- Documentation/sphinx/kernel_abi.py | 173 +++++++++++++++++++++++++++++++++++++ 1 file changed, 173 insertions(+) create mode 100644 Documentation/sphinx/kernel_abi.py (limited to 'Documentation/sphinx/kernel_abi.py') diff --git a/Documentation/sphinx/kernel_abi.py b/Documentation/sphinx/kernel_abi.py new file mode 100644 index 000000000..5667f207d --- /dev/null +++ b/Documentation/sphinx/kernel_abi.py @@ -0,0 +1,173 @@ +# -*- coding: utf-8; mode: python -*- +# coding=utf-8 +# SPDX-License-Identifier: GPL-2.0 +# +""" + kernel-abi + ~~~~~~~~~~ + + Implementation of the ``kernel-abi`` reST-directive. + + :copyright: Copyright (C) 2016 Markus Heiser + :copyright: Copyright (C) 2016-2020 Mauro Carvalho Chehab + :maintained-by: Mauro Carvalho Chehab + :license: GPL Version 2, June 1991 see Linux/COPYING for details. + + The ``kernel-abi`` (:py:class:`KernelCmd`) directive calls the + AbiParser class to parse the Kernel ABI files. + + Overview of directive's argument and options. + + .. code-block:: rst + + .. kernel-abi:: + :debug: + + The argument ```` is required. It contains the + location of the ABI files to be parsed. + + ``debug`` + Inserts a code-block with the *raw* reST. Sometimes it is helpful to see + what reST is generated. + +""" + +import os +import re +import sys + +from docutils import nodes, statemachine +from docutils.statemachine import ViewList +from docutils.parsers.rst import directives, Directive +from sphinx.util.docutils import switch_source_input +from sphinx.util import logging + +srctree = os.path.abspath(os.environ["srctree"]) +sys.path.insert(0, os.path.join(srctree, "tools/lib/python")) + +from abi.abi_parser import AbiParser + +__version__ = "1.0" + +logger = logging.getLogger('kernel_abi') +path = os.path.join(srctree, "Documentation/ABI") + +_kernel_abi = None + +def get_kernel_abi(): + """ + Initialize kernel_abi global var, if not initialized yet. + + This is needed to avoid warnings during Sphinx module initialization. + """ + global _kernel_abi + + if not _kernel_abi: + # Parse ABI symbols only once + _kernel_abi = AbiParser(path, logger=logger) + _kernel_abi.parse_abi() + _kernel_abi.check_issues() + + return _kernel_abi + +def setup(app): + + app.add_directive("kernel-abi", KernelCmd) + return { + "version": __version__, + "parallel_read_safe": True, + "parallel_write_safe": True + } + + +class KernelCmd(Directive): + """KernelABI (``kernel-abi``) directive""" + + required_arguments = 1 + optional_arguments = 3 + has_content = False + final_argument_whitespace = True + parser = None + + option_spec = { + "debug": directives.flag, + "no-symbols": directives.flag, + "no-files": directives.flag, + } + + def run(self): + kernel_abi = get_kernel_abi() + + doc = self.state.document + if not doc.settings.file_insertion_enabled: + raise self.warning("docutils: file insertion disabled") + + env = self.state.document.settings.env + content = ViewList() + node = nodes.section() + + abi_type = self.arguments[0] + + if "no-symbols" in self.options: + show_symbols = False + else: + show_symbols = True + + if "no-files" in self.options: + show_file = False + else: + show_file = True + + tab_width = self.options.get('tab-width', + self.state.document.settings.tab_width) + + old_f = None + n = 0 + n_sym = 0 + for msg, f, ln in kernel_abi.doc(show_file=show_file, + show_symbols=show_symbols, + filter_path=abi_type): + n_sym += 1 + msg_list = statemachine.string2lines(msg, tab_width, + convert_whitespace=True) + if "debug" in self.options: + lines = [ + "", "", ".. code-block:: rst", + " :linenos:", "" + ] + for m in msg_list: + lines.append(" " + m) + else: + lines = msg_list + + for line in lines: + # sphinx counts lines from 0 + content.append(line, f, ln - 1) + n += 1 + + if f != old_f: + # Add the file to Sphinx build dependencies if the file exists + fname = os.path.join(srctree, f) + if os.path.isfile(fname): + env.note_dependency(fname) + + old_f = f + + # Sphinx doesn't like to parse big messages. So, let's + # add content symbol by symbol + if content: + self.do_parse(content, node) + content = ViewList() + + if show_symbols and not show_file: + logger.verbose("%s ABI: %i symbols (%i ReST lines)" % (abi_type, n_sym, n)) + elif not show_symbols and show_file: + logger.verbose("%s ABI: %i files (%i ReST lines)" % (abi_type, n_sym, n)) + else: + logger.verbose("%s ABI: %i data (%i ReST lines)" % (abi_type, n_sym, n)) + + return node.children + + def do_parse(self, content, node): + with switch_source_input(self.state, content): + self.state.nested_parse(content, 0, node, match_titles=1) -- cgit v1.3.1