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13 June 2022, 11:31:42 UTC
Revision b5b1404d0815894de0690de8a1ab58269e56eae6 authored by Linus Torvalds on 12 August 2018, 19:19:42 UTC, committed by Linus Torvalds on 12 August 2018, 19:19:42 UTC 
init: rename and re-order boot_cpu_state_init()
 
This is purely a preparatory patch for upcoming changes during the 4.19
merge window.

We have a function called "boot_cpu_state_init()" that isn't really
about the bootup cpu state: that is done much earlier by the similarly
named "boot_cpu_init()" (note lack of "state" in name).

This function initializes some hotplug CPU state, and needs to run after
the percpu data has been properly initialized.  It even has a comment to
that effect.

Except it _doesn't_ actually run after the percpu data has been properly
initialized.  On x86 it happens to do that, but on at least arm and
arm64, the percpu base pointers are initialized by the arch-specific
'smp_prepare_boot_cpu()' hook, which ran _after_ boot_cpu_state_init().

This had some unexpected results, and in particular we have a patch
pending for the merge window that did the obvious cleanup of using
'this_cpu_write()' in the cpu hotplug init code:

  -       per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE;
  +       this_cpu_write(cpuhp_state.state, CPUHP_ONLINE);

which is obviously the right thing to do.  Except because of the
ordering issue, it actually failed miserably and unexpectedly on arm64.

So this just fixes the ordering, and changes the name of the function to
be 'boot_cpu_hotplug_init()' to make it obvious that it's about cpu
hotplug state, because the core CPU state was supposed to have already
been done earlier.

Marked for stable, since the (not yet merged) patch that will show this
problem is marked for stable.

Reported-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent d6dd643
Raw File
Tip revision: b5b1404d0815894de0690de8a1ab58269e56eae6 authored by Linus Torvalds on 12 August 2018, 19:19:42 UTC
init: rename and re-order boot_cpu_state_init()
Tip revision: b5b1404
Kbuild 
# SPDX-License-Identifier: GPL-2.0
#
# Kbuild for top-level directory of the kernel
# This file takes care of the following:
# 1) Generate bounds.h
# 2) Generate timeconst.h
# 3) Generate asm-offsets.h (may need bounds.h and timeconst.h)
# 4) Check for missing system calls
# 5) Generate constants.py (may need bounds.h)

#####
# 1) Generate bounds.h

bounds-file := include/generated/bounds.h

always  := $(bounds-file)
targets := kernel/bounds.s

# We use internal kbuild rules to avoid the "is up to date" message from make
kernel/bounds.s: kernel/bounds.c FORCE
	$(call if_changed_dep,cc_s_c)

$(obj)/$(bounds-file): kernel/bounds.s FORCE
	$(call filechk,offsets,__LINUX_BOUNDS_H__)

#####
# 2) Generate timeconst.h

timeconst-file := include/generated/timeconst.h

targets += $(timeconst-file)

quiet_cmd_gentimeconst = GEN     $@
define cmd_gentimeconst
	(echo $(CONFIG_HZ) | bc -q $< ) > $@
endef
define filechk_gentimeconst
	(echo $(CONFIG_HZ) | bc -q $< )
endef

$(obj)/$(timeconst-file): kernel/time/timeconst.bc FORCE
	$(call filechk,gentimeconst)

#####
# 3) Generate asm-offsets.h
#

offsets-file := include/generated/asm-offsets.h

always  += $(offsets-file)
targets += arch/$(SRCARCH)/kernel/asm-offsets.s

# We use internal kbuild rules to avoid the "is up to date" message from make
arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
                                      $(obj)/$(timeconst-file) $(obj)/$(bounds-file) FORCE
	$(call if_changed_dep,cc_s_c)

$(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE
	$(call filechk,offsets,__ASM_OFFSETS_H__)

#####
# 4) Check for missing system calls
#

always += missing-syscalls
targets += missing-syscalls

quiet_cmd_syscalls = CALL    $<
      cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags) $(missing_syscalls_flags)

missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE
	$(call cmd,syscalls)

#####
# 5) Generate constants for Python GDB integration
#

extra-$(CONFIG_GDB_SCRIPTS) += build_constants_py

build_constants_py: $(obj)/$(timeconst-file) $(obj)/$(bounds-file)
	@$(MAKE) $(build)=scripts/gdb/linux $@

# Keep these three files during make clean
no-clean-files := $(bounds-file) $(offsets-file) $(timeconst-file)
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