From: Sebastian Andrzej Siewior <bige...@linutronix.de>

arch_hw_breakpoint_init() holds get_online_cpus() while registerring the
hotplug callbacks.

cpuhp_setup_state() invokes get_online_cpus() as well. This is correct, but
prevents the conversion of the hotplug locking to a percpu rwsem.

Use cpuhp_setup_state_locked() to avoid the nested call.

Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Cc: Will Deacon <will.dea...@arm.com>
Cc: Mark Rutland <mark.rutl...@arm.com>
Cc: Russell King <li...@armlinux.org.uk>
Cc: linux-arm-ker...@lists.infradead.org

---
 arch/arm/kernel/hw_breakpoint.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -1098,8 +1098,9 @@ static int __init arch_hw_breakpoint_ini
         * assume that a halting debugger will leave the world in a nice state
         * for us.
         */
-       ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "arm/hw_breakpoint:online",
-                               dbg_reset_online, NULL);
+       ret = cpuhp_setup_state_locked(CPUHP_AP_ONLINE_DYN,
+                                      "arm/hw_breakpoint:online",
+                                      dbg_reset_online, NULL);
        unregister_undef_hook(&debug_reg_hook);
        if (WARN_ON(ret < 0) || !cpumask_empty(&debug_err_mask)) {
                core_num_brps = 0;


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