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 --- usr/include/.gitignore | 2 + usr/include/Makefile | 188 +++++++++++++++++++++++++++++++++++++++++++ usr/include/headers_check.pl | 96 ++++++++++++++++++++++ 3 files changed, 286 insertions(+) create mode 100644 usr/include/.gitignore create mode 100644 usr/include/Makefile create mode 100755 usr/include/headers_check.pl (limited to 'usr/include') diff --git a/usr/include/.gitignore b/usr/include/.gitignore new file mode 100644 index 000000000..17b0ba1bd --- /dev/null +++ b/usr/include/.gitignore @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +/*/ diff --git a/usr/include/Makefile b/usr/include/Makefile new file mode 100644 index 000000000..ee69dd9d9 --- /dev/null +++ b/usr/include/Makefile @@ -0,0 +1,188 @@ +# SPDX-License-Identifier: GPL-2.0-only + +# Unlike the kernel space, exported headers are written in standard C. +# - Forbid C++ style comments +# - Use '__inline__', '__asm__' instead of 'inline', 'asm' +# +# -std=c90 (equivalent to -ansi) catches the violation of those. +# We cannot go as far as adding -Wpedantic since it emits too many warnings. +UAPI_CFLAGS := -std=c90 -Werror=implicit-function-declaration +UAPI_ARCH := $(or $(HEADER_ARCH),$(SRCARCH)) + +override c_flags = $(KBUILD_USERCFLAGS) $(UAPI_CFLAGS) -Wp,-MMD,$(depfile) +cxx_flags = $(filter-out -Wmissing-prototypes -Wstrict-prototypes -std=%, $(KBUILD_USERCFLAGS)) -std=c++98 + +# The following are excluded for now because they fail to build. +# +# Do not add a new header to the blacklist without legitimate reason. +# Please consider to fix the header first. +# +# Sorted alphabetically. +no-header-test += asm/ucontext.h +no-header-test += drm/vmwgfx_drm.h +no-header-test += linux/am437x-vpfe.h +no-header-test += linux/coda.h +no-header-test += linux/cyclades.h +no-header-test += linux/errqueue.h +no-header-test += linux/hdlc/ioctl.h +no-header-test += linux/ivtv.h +no-header-test += linux/matroxfb.h +no-header-test += linux/omap3isp.h +no-header-test += linux/omapfb.h +no-header-test += linux/patchkey.h +no-header-test += linux/phonet.h +no-header-test += linux/sctp.h +no-header-test += linux/sysctl.h +no-header-test += linux/usb/audio.h +no-header-test += linux/v4l2-mediabus.h +no-header-test += linux/v4l2-subdev.h +no-header-test += linux/videodev2.h +no-header-test += linux/vm_sockets.h +no-header-test += sound/asequencer.h +no-header-test += sound/asoc.h +no-header-test += sound/asound.h +no-header-test += sound/compress_offload.h +no-header-test += sound/emu10k1.h +no-header-test += sound/sfnt_info.h +no-header-test += xen/evtchn.h +no-header-test += xen/gntdev.h +no-header-test += xen/privcmd.h + +# More headers are broken in some architectures + +ifneq ($(filter arc openrisc xtensa nios2, $(UAPI_ARCH)),) +no-header-test += linux/bpf_perf_event.h +endif + +ifeq ($(UAPI_ARCH),sparc) +no-header-test += asm/uctx.h +no-header-test += asm/fbio.h +endif + +# asm-generic/*.h is used by asm/*.h, and should not be included directly +no-header-test += asm-generic/% + +# The following are not compatible with C++. +# +# Do not add a new header to the list without legitimate reason. +# Please consider to fix the header first. +# +# Sorted alphabetically. +no-header-test-cxx += linux/auto_dev-ioctl.h +no-header-test-cxx += linux/map_to_14segment.h +no-header-test-cxx += linux/map_to_7segment.h +no-header-test-cxx += linux/netfilter/xt_sctp.h +no-header-test-cxx += linux/target_core_user.h +no-header-test-cxx += linux/vhost.h +no-header-test-cxx += linux/vhost_types.h +no-header-test-cxx += linux/virtio_net.h +no-header-test-cxx += linux/virtio_ring.h +no-header-test-cxx += scsi/fc/fc_els.h + +ifeq ($(UAPI_ARCH),x86) +no-header-test-cxx += asm/elf.h +endif + +# The following are using libc header and types. +# +# Do not add a new header to the list without legitimate reason. +# Please consider to fix the header first. +# +# Sorted alphabetically. +uses-libc += linux/a.out.h +uses-libc += linux/atmbr2684.h +uses-libc += linux/auto_dev-ioctl.h +uses-libc += linux/auto_fs.h +uses-libc += linux/auto_fs4.h +uses-libc += linux/btrfs_tree.h +uses-libc += linux/cec-funcs.h +uses-libc += linux/cec.h +uses-libc += linux/dvb/dmx.h +uses-libc += linux/dvb/video.h +uses-libc += linux/ethtool.h +uses-libc += linux/ethtool_netlink.h +uses-libc += linux/fuse.h +uses-libc += linux/gsmmux.h +uses-libc += linux/icmp.h +uses-libc += linux/idxd.h +uses-libc += linux/if.h +uses-libc += linux/if_arp.h +uses-libc += linux/if_bonding.h +uses-libc += linux/if_pppox.h +uses-libc += linux/if_tunnel.h +uses-libc += linux/input.h +uses-libc += linux/ip6_tunnel.h +uses-libc += linux/joystick.h +uses-libc += linux/llc.h +uses-libc += linux/mctp.h +uses-libc += linux/mdio.h +uses-libc += linux/mii.h +uses-libc += linux/mptcp.h +uses-libc += linux/netdevice.h +uses-libc += linux/netfilter/xt_RATEEST.h +uses-libc += linux/netfilter/xt_hashlimit.h +uses-libc += linux/netfilter/xt_physdev.h +uses-libc += linux/netfilter/xt_rateest.h +uses-libc += linux/netfilter_arp/arp_tables.h +uses-libc += linux/netfilter_arp/arpt_mangle.h +uses-libc += linux/netfilter_bridge.h +uses-libc += linux/netfilter_bridge/ebtables.h +uses-libc += linux/netfilter_ipv4.h +uses-libc += linux/netfilter_ipv4/ip_tables.h +uses-libc += linux/netfilter_ipv6.h +uses-libc += linux/netfilter_ipv6/ip6_tables.h +uses-libc += linux/route.h +uses-libc += linux/shm.h +uses-libc += linux/soundcard.h +uses-libc += linux/string.h +uses-libc += linux/tipc_config.h +uses-libc += linux/uhid.h +uses-libc += linux/uinput.h +uses-libc += linux/vhost.h +uses-libc += linux/vhost_types.h +uses-libc += linux/virtio_ring.h +uses-libc += linux/wireless.h +uses-libc += regulator/regulator.h +uses-libc += scsi/fc/fc_els.h + +ifeq ($(UAPI_ARCH),hexagon) +uses-libc += asm/sigcontext.h +endif + +ifeq ($(UAPI_ARCH),nios2) +uses-libc += asm/ptrace.h +endif + +ifeq ($(UAPI_ARCH),s390) +uses-libc += asm/chpid.h +uses-libc += asm/chsc.h +endif + +always-y := $(patsubst $(obj)/%.h,%.hdrtest, $(shell find $(obj) -name '*.h' 2>/dev/null)) + +# $(cc-option) forces '-x c' which breaks '-x c++' detection. +cc-can-compile-cxx := $(call try-run,$(CC) $(CLANG_FLAGS) -c -x c++ /dev/null -o "$$TMP", 1) + +target-libc = $(filter $(uses-libc), $*.h) +target-can-compile = $(filter-out $(no-header-test), $*.h) +target-can-compile-cxx = $(and $(cc-can-compile-cxx), $(target-can-compile), $(filter-out $(no-header-test-cxx), $*.h)) + +hdrtest-flags = -fsyntax-only -Werror \ + -nostdinc -I $(obj) $(if $(target-libc), -I $(srctree)/usr/dummy-include) + +# Include the header twice to detect missing include guard. +quiet_cmd_hdrtest = HDRTEST $< + cmd_hdrtest = \ + $(CC) $(c_flags) $(hdrtest-flags) -x c /dev/null \ + $(if $(target-can-compile), -include $< -include $<); \ + $(if $(target-can-compile-cxx), \ + $(CC) $(cxx_flags) $(hdrtest-flags) -x c++ /dev/null -include $<;) \ + $(PERL) $(src)/headers_check.pl $(obj) $<; \ + touch $@ + +$(obj)/%.hdrtest: $(obj)/%.h $(src)/headers_check.pl FORCE + $(call if_changed_dep,hdrtest) + +# Since GNU Make 4.3, $(patsubst $(obj)/%/,%,$(wildcard $(obj)/*/)) works. +# To support older Make versions, use a somewhat tedious way. +clean-files += $(filter-out Makefile headers_check.pl, $(notdir $(wildcard $(obj)/*))) diff --git a/usr/include/headers_check.pl b/usr/include/headers_check.pl new file mode 100755 index 000000000..6cd6eb652 --- /dev/null +++ b/usr/include/headers_check.pl @@ -0,0 +1,96 @@ +#!/usr/bin/env perl +# SPDX-License-Identifier: GPL-2.0 +# +# headers_check.pl execute a number of trivial consistency checks +# +# Usage: headers_check.pl dir [files...] +# dir: dir to look for included files +# files: list of files to check +# +# The script reads the supplied files line by line and: +# +# 1) for each include statement it checks if the +# included file actually exists. +# Only include files located in asm* and linux* are checked. +# The rest are assumed to be system include files. +# +# 2) It is checked that prototypes does not use "extern" +# +# 3) Check for leaked CONFIG_ symbols + +use warnings; +use strict; +use File::Basename; + +my ($dir, @files) = @ARGV; + +my $ret = 0; +my $line; +my $lineno = 0; +my $filename; + +foreach my $file (@files) { + $filename = $file; + + open(my $fh, '<', $filename) + or die "$filename: $!\n"; + $lineno = 0; + while ($line = <$fh>) { + $lineno++; + &check_include(); + &check_asm_types(); + &check_declarations(); + } + close $fh; +} +exit $ret; + +sub check_include +{ + if ($line =~ m/^\s*#\s*include\s+<((asm|linux).*)>/) { + my $inc = $1; + my $found; + $found = stat($dir . "/" . $inc); + if (!$found) { + printf STDERR "$filename:$lineno: included file '$inc' is not exported\n"; + $ret = 1; + } + } +} + +sub check_declarations +{ + # soundcard.h is what it is + if ($line =~ m/^void seqbuf_dump\(void\);/) { + return; + } + # drm headers are being C++ friendly + if ($line =~ m/^extern "C"/) { + return; + } + if ($line =~ m/^(\s*extern|unsigned|char|short|int|long|void)\b/) { + printf STDERR "$filename:$lineno: " . + "userspace cannot reference function or " . + "variable defined in the kernel\n"; + $ret = 1; + } +} + +my $linux_asm_types; +sub check_asm_types +{ + if ($filename =~ /types.h|int-l64.h|int-ll64.h/o) { + return; + } + if ($lineno == 1) { + $linux_asm_types = 0; + } elsif ($linux_asm_types >= 1) { + return; + } + if ($line =~ m/^\s*#\s*include\s+/) { + $linux_asm_types = 1; + printf STDERR "$filename:$lineno: " . + "include of is preferred over \n"; + $ret = 1; + } +} -- cgit v1.3.1