Merge tag 'driver-core-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here are the set of driver core and kernfs changes for 6.8-rc1.
  Nothing major in here this release cycle, just lots of small cleanups
  and some tweaks on kernfs that in the very end, got reverted and will
  come back in a safer way next release cycle.

  Included in here are:

   - more driver core 'const' cleanups and fixes

   - fw_devlink=rpm is now the default behavior

   - kernfs tiny changes to remove some string functions

   - cpu handling in the driver core is updated to work better on many
     systems that add topologies and cpus after booting

   - other minor changes and cleanups

  All of the cpu handling patches have been acked by the respective
  maintainers and are coming in here in one series. Everything has been
  in linux-next for a while with no reported issues"

* tag 'driver-core-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (51 commits)
  Revert "kernfs: convert kernfs_idr_lock to an irq safe raw spinlock"
  kernfs: convert kernfs_idr_lock to an irq safe raw spinlock
  class: fix use-after-free in class_register()
  PM: clk: make pm_clk_add_notifier() take a const pointer
  EDAC: constantify the struct bus_type usage
  kernfs: fix reference to renamed function
  driver core: device.h: fix Excess kernel-doc description warning
  driver core: class: fix Excess kernel-doc description warning
  driver core: mark remaining local bus_type variables as const
  driver core: container: make container_subsys const
  driver core: bus: constantify subsys_register() calls
  driver core: bus: make bus_sort_breadthfirst() take a const pointer
  kernfs: d_obtain_alias(NULL) will do the right thing...
  driver core: Better advertise dev_err_probe()
  kernfs: Convert kernfs_path_from_node_locked() from strlcpy() to strscpy()
  kernfs: Convert kernfs_name_locked() from strlcpy() to strscpy()
  kernfs: Convert kernfs_walk_ns() from strlcpy() to strscpy()
  initramfs: Expose retained initrd as sysfs file
  fs/kernfs/dir: obey S_ISGID
  kernel/cgroup: use kernfs_create_dir_ns()
  ...

1 files changed, 31 insertions, 8 deletions

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 548491de818e..47de0f140ba6 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -525,19 +525,42 @@ bool cpu_is_hotpluggable(unsigned int cpu)
 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
 
 #ifdef CONFIG_GENERIC_CPU_DEVICES
-static DEFINE_PER_CPU(struct cpu, cpu_devices);
-#endif
+DEFINE_PER_CPU(struct cpu, cpu_devices);
+
+bool __weak arch_cpu_is_hotpluggable(int cpu)
+{
+	return false;
+}
+
+int __weak arch_register_cpu(int cpu)
+{
+	struct cpu *c = &per_cpu(cpu_devices, cpu);
+
+	c->hotpluggable = arch_cpu_is_hotpluggable(cpu);
+
+	return register_cpu(c, cpu);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+void __weak arch_unregister_cpu(int num)
+{
+	unregister_cpu(&per_cpu(cpu_devices, num));
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+#endif /* CONFIG_GENERIC_CPU_DEVICES */
 
 static void __init cpu_dev_register_generic(void)
 {
-#ifdef CONFIG_GENERIC_CPU_DEVICES
-	int i;
+	int i, ret;
 
-	for_each_possible_cpu(i) {
-		if (register_cpu(&per_cpu(cpu_devices, i), i))
-			panic("Failed to register CPU device");
+	if (!IS_ENABLED(CONFIG_GENERIC_CPU_DEVICES))
+		return;
+
+	for_each_present_cpu(i) {
+		ret = arch_register_cpu(i);
+		if (ret)
+			pr_warn("register_cpu %d failed (%d)\n", i, ret);
 	}
-#endif
 }
 
 #ifdef CONFIG_GENERIC_CPU_VULNERABILITIES