kernel/linux.git/include/linux/cpuhplock.h, branch v7.2-rc1

cpu: Add lockdep_is_cpus_held()/lockdep_is_cpus_write_held() stubs for !CONFIG_HOTPLUG_CPU

2026-06-04T08:55:27+00:00

lockdep_is_cpus_held() and lockdep_is_cpus_write_held() are undefined when !CONFIG_HOTPLUG_CPU. This is ok because their few callers protect the calls with a "if (IS_ENABLED(CONFIG_HOTPLUG_CPU) ..." check. It is error prone to require callers to protect lockdep_is_cpus_held() and lockdep_is_cpus_write_held() with an IS_ENABLED(CONFIG_HOTPLUG_CPU) check while the custom for equivalent functions, for example the more prevalent lockdep_is_held(), is to not require similar protection. It is also inconsistent with CPU hotplug lockdep code self since related call lockdep_assert_cpus_held() does not require protection. Create stubs for lockdep_is_cpus_held() and lockdep_is_cpus_write_held() that returns 1 (LOCK_STATE_UNKNOWN/LOCK_STATE_HELD) when !CONFIG_HOTPLUG_CPU. This makes the CPU hotplug lockdep checks consistent while following existing lockdep custom. Drop the "extern" from the function declaration as part of the move to match kernel coding style. Keep the IS_ENABLED(CONFIG_HOTPLUG_CPU) checks in existing users since removing them would change the logic of these expressions. Reported-by: Sashiko Signed-off-by: Reinette Chatre Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/7484f0b58fd86153d445819cc4e172adba16cff9.1780543665.git.reinette.chatre@intel.com Closes: https://sashiko.dev/#/patchset/cover.1780456704.git.reinette.chatre%40intel.com?part=1

cpu: Provide lockdep check for CPU hotplug lock write-held

2026-02-03T14:23:33+00:00

cpuset modifies partitions, including isolated, while holding the cpu hotplug lock read-held. This means that write-holding the CPU hotplug lock is safe to synchronize against housekeeping cpumask changes. Provide a lockdep check to validate that. Signed-off-by: Frederic Weisbecker Cc: Marco Crivellari Cc: Michal Hocko Cc: Peter Zijlstra Cc: Tejun Heo Cc: Thomas Gleixner Cc: Waiman Long Cc: linux-kernel@vger.kernel.org

cpu/hotplug: Add support for declaring CPU offlining not supported

2024-06-17T15:45:31+00:00

The ACPI MADT mailbox wakeup method doesn't allow to offline a CPU after it has been woken up. Currently, offlining is prevented based on the confidential computing attribute which is set for Intel TDX. But TDX is not the only possible user of the wake up method. The MADT wakeup can be implemented outside of a confidential computing environment. Offline support is a property of the wakeup method, not the CoCo implementation. Introduce cpu_hotplug_disable_offlining() that can be called to indicate that CPU offlining should be disabled. This function is going to replace CC_ATTR_HOTPLUG_DISABLED for ACPI MADT wakeup method. Signed-off-by: Kirill A. Shutemov Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Thomas Gleixner Tested-by: Tao Liu Link: https://lore.kernel.org/r/20240614095904.1345461-4-kirill.shutemov@linux.intel.com

cpu: Drop "extern" from function declarations in cpuhplock.h

2024-06-10T06:50:05+00:00

This file was created with a direct cut and paste from cpu.h so kept the legacy declaration style. But the Linux coding standard for function declarations in header files is to avoid use of "extern". Drop "extern" from all function declarations. Signed-off-by: Tony Luck Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20240610003927.341707-3-tony.luck@intel.com

cpu: Move CPU hotplug function declarations into their own header

2024-06-10T06:50:01+00:00

Avoid upcoming #include hell when wants to use lockdep_assert_cpus_held() and creates a #include loop that would break the build for arch/riscv. [ bp: s/cpu/CPU/g ] Signed-off-by: Tony Luck Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20240610003927.341707-2-tony.luck@intel.com