Merge tag 'kgdb-4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux

Pull kgdb updates from Daniel Thompson:
 "Mostly clean ups although while Doug's was chasing down a odd lockdep
  warning he also did some work to improved debugger resilience when
  some CPUs fail to respond to the round up request.

  The main changes are:

   - Fixing a lockdep warning on architectures that cannot use an NMI
     for the round up plus related changes to make CPU round up and all
     CPU backtrace more resilient.

   - Constify the arch ops tables

   - A couple of other small clean ups

  Two of the three patchsets here include changes that spill over into
  arch/. Changes in the arch space are relatively narrow in scope (and
  directly related to kgdb). Didn't get comprehensive acks but all
  impacted maintainers were Cc:ed in good time"

* tag 'kgdb-4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux:
  kgdb/treewide: constify struct kgdb_arch arch_kgdb_ops
  mips/kgdb: prepare arch_kgdb_ops for constness
  kdb: use bool for binary state indicators
  kdb: Don't back trace on a cpu that didn't round up
  kgdb: Don't round up a CPU that failed rounding up before
  kgdb: Fix kgdb_roundup_cpus() for arches who used smp_call_function()
  kgdb: Remove irq flags from roundup

arch/arc/kernel/kgdb.c

@@ -192,19 +192,13 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
 	instruction_pointer(regs) = ip;
 }
 
-static void kgdb_call_nmi_hook(void *ignored)
+void kgdb_call_nmi_hook(void *ignored)
 {
+	/* Default implementation passes get_irq_regs() but we don't */
 	kgdb_nmicallback(raw_smp_processor_id(), NULL);
 }
 
-void kgdb_roundup_cpus(unsigned long flags)
-{
-	local_irq_enable();
-	smp_call_function(kgdb_call_nmi_hook, NULL, 0);
-	local_irq_disable();
-}
-
-struct kgdb_arch arch_kgdb_ops = {
+const struct kgdb_arch arch_kgdb_ops = {
 	/* breakpoint instruction: TRAP_S 0x3 */
 #ifdef CONFIG_CPU_BIG_ENDIAN
 	.gdb_bpt_instr		= {0x78, 0x7e},