20 files changed, 125 insertions, 141 deletions

diff --git a/arch/arc/kernel/kgdb.c b/arch/arc/kernel/kgdb.c
index 9a3c34af2ae8..96bca9963c63 100644
--- a/arch/arc/kernel/kgdb.c
+++ b/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},
diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c
index caa0dbe3dc61..6a95b9296640 100644
--- a/arch/arm/kernel/kgdb.c
+++ b/arch/arm/kernel/kgdb.c
@@ -170,18 +170,6 @@ static struct undef_hook kgdb_compiled_brkpt_hook = {
         .fn                     = kgdb_compiled_brk_fn
 };
 
-static void kgdb_call_nmi_hook(void *ignored)
-{
-       kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
-}
-
-void kgdb_roundup_cpus(unsigned long flags)
-{
-       local_irq_enable();
-       smp_call_function(kgdb_call_nmi_hook, NULL, 0);
-       local_irq_disable();
-}
-
 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 {
         struct pt_regs *regs = args->regs;
@@ -274,7 +262,7 @@ int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
  * and we handle the normal undef case within the do_undefinstr
  * handler.
  */
-struct kgdb_arch arch_kgdb_ops = {
+const struct kgdb_arch arch_kgdb_ops = {
 #ifndef __ARMEB__
         .gdb_bpt_instr          = {0xfe, 0xde, 0xff, 0xe7}
 #else /* ! __ARMEB__ */
diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c
index a20de58061a8..ce46c4cdf368 100644
--- a/arch/arm64/kernel/kgdb.c
+++ b/arch/arm64/kernel/kgdb.c
@@ -284,18 +284,6 @@ static struct step_hook kgdb_step_hook = {
         .fn             = kgdb_step_brk_fn
 };
 
-static void kgdb_call_nmi_hook(void *ignored)
-{
-        kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
-}
-
-void kgdb_roundup_cpus(unsigned long flags)
-{
-        local_irq_enable();
-        smp_call_function(kgdb_call_nmi_hook, NULL, 0);
-        local_irq_disable();
-}
-
 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 {
         struct pt_regs *regs = args->regs;
@@ -357,7 +345,7 @@ void kgdb_arch_exit(void)
         unregister_die_notifier(&kgdb_notifier);
 }
 
-struct kgdb_arch arch_kgdb_ops;
+const struct kgdb_arch arch_kgdb_ops;
 
 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 {
diff --git a/arch/h8300/kernel/kgdb.c b/arch/h8300/kernel/kgdb.c
index 1a1d30cb0609..602e478afbd5 100644
--- a/arch/h8300/kernel/kgdb.c
+++ b/arch/h8300/kernel/kgdb.c
@@ -129,7 +129,7 @@ void kgdb_arch_exit(void)
         /* Nothing to do */
 }
 
-struct kgdb_arch arch_kgdb_ops = {
+const struct kgdb_arch arch_kgdb_ops = {
         /* Breakpoint instruction: trapa #2 */
         .gdb_bpt_instr = { 0x57, 0x20 },
 };
diff --git a/arch/hexagon/kernel/kgdb.c b/arch/hexagon/kernel/kgdb.c
index 16c24b22d0b2..3fabd3ff3bbd 100644
--- a/arch/hexagon/kernel/kgdb.c
+++ b/arch/hexagon/kernel/kgdb.c
@@ -83,7 +83,7 @@ struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
         { "syscall_nr", GDB_SIZEOF_REG, offsetof(struct pt_regs, syscall_nr)},
 };
 
-struct kgdb_arch arch_kgdb_ops = {
+const struct kgdb_arch arch_kgdb_ops = {
         /* trap0(#0xDB) 0x0cdb0054 */
         .gdb_bpt_instr = {0x54, 0x00, 0xdb, 0x0c},
 };
@@ -115,38 +115,6 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
         instruction_pointer(regs) = pc;
 }
 
-#ifdef CONFIG_SMP
-
-/**
- * kgdb_roundup_cpus - Get other CPUs into a holding pattern
- * @flags: Current IRQ state
- *
- * On SMP systems, we need to get the attention of the other CPUs
- * and get them be in a known state.  This should do what is needed
- * to get the other CPUs to call kgdb_wait(). Note that on some arches,
- * the NMI approach is not used for rounding up all the CPUs. For example,
- * in case of MIPS, smp_call_function() is used to roundup CPUs. In
- * this case, we have to make sure that interrupts are enabled before
- * calling smp_call_function(). The argument to this function is
- * the flags that will be used when restoring the interrupts. There is
- * local_irq_save() call before kgdb_roundup_cpus().
- *
- * On non-SMP systems, this is not called.
- */
-
-static void hexagon_kgdb_nmi_hook(void *ignored)
-{
-        kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
-}
-
-void kgdb_roundup_cpus(unsigned long flags)
-{
-        local_irq_enable();
-        smp_call_function(hexagon_kgdb_nmi_hook, NULL, 0);
-        local_irq_disable();
-}
-#endif
-
 
 /*  Not yet working  */
 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs,
diff --git a/arch/microblaze/kernel/kgdb.c b/arch/microblaze/kernel/kgdb.c
index 6366f69d118e..130cd0f064ce 100644
--- a/arch/microblaze/kernel/kgdb.c
+++ b/arch/microblaze/kernel/kgdb.c
@@ -143,7 +143,7 @@ void kgdb_arch_exit(void)
 /*
  * Global data
  */
-struct kgdb_arch arch_kgdb_ops = {
+const struct kgdb_arch arch_kgdb_ops = {
 #ifdef __MICROBLAZEEL__
         .gdb_bpt_instr = {0x18, 0x00, 0x0c, 0xba}, /* brki r16, 0x18 */
 #else
diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c
index eb6c0d582626..149100e1bc7c 100644
--- a/arch/mips/kernel/kgdb.c
+++ b/arch/mips/kernel/kgdb.c
@@ -207,7 +207,7 @@ void arch_kgdb_breakpoint(void)
                 ".set\treorder");
 }
 
-static void kgdb_call_nmi_hook(void *ignored)
+void kgdb_call_nmi_hook(void *ignored)
 {
         mm_segment_t old_fs;
 
@@ -219,13 +219,6 @@ static void kgdb_call_nmi_hook(void *ignored)
         set_fs(old_fs);
 }
 
-void kgdb_roundup_cpus(unsigned long flags)
-{
-        local_irq_enable();
-        smp_call_function(kgdb_call_nmi_hook, NULL, 0);
-        local_irq_disable();
-}
-
 static int compute_signal(int tt)
 {
         struct hard_trap_info *ht;
@@ -394,18 +387,16 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code,
         return -1;
 }
 
-struct kgdb_arch arch_kgdb_ops;
+const struct kgdb_arch arch_kgdb_ops = {
+#ifdef CONFIG_CPU_BIG_ENDIAN
+        .gdb_bpt_instr = { spec_op << 2, 0x00, 0x00, break_op },
+#else
+        .gdb_bpt_instr = { break_op, 0x00, 0x00, spec_op << 2 },
+#endif
+};
 
 int kgdb_arch_init(void)
 {
-        union mips_instruction insn = {
-                .r_format = {
-                        .opcode = spec_op,
-                        .func   = break_op,
-                }
-        };
-        memcpy(arch_kgdb_ops.gdb_bpt_instr, insn.byte, BREAK_INSTR_SIZE);
-
         register_die_notifier(&kgdb_notifier);
 
         return 0;
diff --git a/arch/nios2/kernel/kgdb.c b/arch/nios2/kernel/kgdb.c
index 117859122d1c..37b25f844a2d 100644
--- a/arch/nios2/kernel/kgdb.c
+++ b/arch/nios2/kernel/kgdb.c
@@ -165,7 +165,7 @@ void kgdb_arch_exit(void)
         /* Nothing to do */
 }
 
-struct kgdb_arch arch_kgdb_ops = {
+const struct kgdb_arch arch_kgdb_ops = {
         /* Breakpoint instruction: trap 30 */
         .gdb_bpt_instr = { 0xba, 0x6f, 0x3b, 0x00 },
 };
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
index 59c578f865aa..e1865565f0ae 100644
--- a/arch/powerpc/kernel/kgdb.c
+++ b/arch/powerpc/kernel/kgdb.c
@@ -117,14 +117,14 @@ int kgdb_skipexception(int exception, struct pt_regs *regs)
         return kgdb_isremovedbreak(regs->nip);
 }
 
-static int kgdb_call_nmi_hook(struct pt_regs *regs)
+static int kgdb_debugger_ipi(struct pt_regs *regs)
 {
         kgdb_nmicallback(raw_smp_processor_id(), regs);
         return 0;
 }
 
 #ifdef CONFIG_SMP
-void kgdb_roundup_cpus(unsigned long flags)
+void kgdb_roundup_cpus(void)
 {
         smp_send_debugger_break();
 }
@@ -477,7 +477,7 @@ int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 /*
  * Global data
  */
-struct kgdb_arch arch_kgdb_ops;
+const struct kgdb_arch arch_kgdb_ops;
 
 static int kgdb_not_implemented(struct pt_regs *regs)
 {
@@ -502,7 +502,7 @@ int kgdb_arch_init(void)
         old__debugger_break_match = __debugger_break_match;
         old__debugger_fault_handler = __debugger_fault_handler;
 
-        __debugger_ipi = kgdb_call_nmi_hook;
+        __debugger_ipi = kgdb_debugger_ipi;
         __debugger = kgdb_debugger;
         __debugger_bpt = kgdb_handle_breakpoint;
         __debugger_sstep = kgdb_singlestep;
diff --git a/arch/sh/kernel/kgdb.c b/arch/sh/kernel/kgdb.c
index d24bd2d2ffad..6d61f8cf4c13 100644
--- a/arch/sh/kernel/kgdb.c
+++ b/arch/sh/kernel/kgdb.c
@@ -311,18 +311,6 @@ BUILD_TRAP_HANDLER(singlestep)
         local_irq_restore(flags);
 }
 
-static void kgdb_call_nmi_hook(void *ignored)
-{
-        kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
-}
-
-void kgdb_roundup_cpus(unsigned long flags)
-{
-        local_irq_enable();
-        smp_call_function(kgdb_call_nmi_hook, NULL, 0);
-        local_irq_disable();
-}
-
 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 {
         int ret;
@@ -379,7 +367,7 @@ void kgdb_arch_exit(void)
         unregister_die_notifier(&kgdb_notifier);
 }
 
-struct kgdb_arch arch_kgdb_ops = {
+const struct kgdb_arch arch_kgdb_ops = {
         /* Breakpoint instruction: trapa #0x3c */
 #ifdef CONFIG_CPU_LITTLE_ENDIAN
         .gdb_bpt_instr          = { 0x3c, 0xc3 },
diff --git a/arch/sparc/kernel/kgdb_32.c b/arch/sparc/kernel/kgdb_32.c
index 639c8e54530a..7580775a14b9 100644
--- a/arch/sparc/kernel/kgdb_32.c
+++ b/arch/sparc/kernel/kgdb_32.c
@@ -166,7 +166,7 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
         regs->npc = regs->pc + 4;
 }
 
-struct kgdb_arch arch_kgdb_ops = {
+const struct kgdb_arch arch_kgdb_ops = {
         /* Breakpoint instruction: ta 0x7d */
         .gdb_bpt_instr          = { 0x91, 0xd0, 0x20, 0x7d },
 };
diff --git a/arch/sparc/kernel/kgdb_64.c b/arch/sparc/kernel/kgdb_64.c
index a68bbddbdba4..5d6c2d287e85 100644
--- a/arch/sparc/kernel/kgdb_64.c
+++ b/arch/sparc/kernel/kgdb_64.c
@@ -195,7 +195,7 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
         regs->tnpc = regs->tpc + 4;
 }
 
-struct kgdb_arch arch_kgdb_ops = {
+const struct kgdb_arch arch_kgdb_ops = {
         /* Breakpoint instruction: ta 0x72 */
         .gdb_bpt_instr          = { 0x91, 0xd0, 0x20, 0x72 },
 };
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index 4792e08ad36b..f45d876983f1 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -1014,7 +1014,7 @@ void flush_dcache_page_all(struct mm_struct *mm, struct page *page)
 }
 
 #ifdef CONFIG_KGDB
-void kgdb_roundup_cpus(unsigned long flags)
+void kgdb_roundup_cpus(void)
 {
         smp_cross_call(&xcall_kgdb_capture, 0, 0, 0);
 }
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 8e36f249646e..5db08425063e 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -422,21 +422,16 @@ static void kgdb_disable_hw_debug(struct pt_regs *regs)
 #ifdef CONFIG_SMP
 /**
  *      kgdb_roundup_cpus - Get other CPUs into a holding pattern
- *      @flags: Current IRQ state
  *
  *      On SMP systems, we need to get the attention of the other CPUs
  *      and get them be in a known state.  This should do what is needed
  *      to get the other CPUs to call kgdb_wait(). Note that on some arches,
  *      the NMI approach is not used for rounding up all the CPUs. For example,
- *      in case of MIPS, smp_call_function() is used to roundup CPUs. In
- *      this case, we have to make sure that interrupts are enabled before
- *      calling smp_call_function(). The argument to this function is
- *      the flags that will be used when restoring the interrupts. There is
- *      local_irq_save() call before kgdb_roundup_cpus().
+ *      in case of MIPS, smp_call_function() is used to roundup CPUs.
  *
  *      On non-SMP systems, this is not called.
  */
-void kgdb_roundup_cpus(unsigned long flags)
+void kgdb_roundup_cpus(void)
 {
         apic->send_IPI_allbutself(APIC_DM_NMI);
 }
@@ -804,7 +799,7 @@ knl_write:
                                   (char *)bpt->saved_instr, BREAK_INSTR_SIZE);
 }
 
-struct kgdb_arch arch_kgdb_ops = {
+const struct kgdb_arch arch_kgdb_ops = {
         /* Breakpoint instruction: */
         .gdb_bpt_instr          = { 0xcc },
         .flags                  = KGDB_HW_BREAKPOINT,
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index e465bb15912d..fbf144aaa749 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -177,22 +177,28 @@ kgdb_arch_handle_exception(int vector, int signo, int err_code,
                            struct pt_regs *regs);
 
 /**
+ *      kgdb_call_nmi_hook - Call kgdb_nmicallback() on the current CPU
+ *      @ignored: This parameter is only here to match the prototype.
+ *
+ *      If you're using the default implementation of kgdb_roundup_cpus()
+ *      this function will be called per CPU.  If you don't implement
+ *      kgdb_call_nmi_hook() a default will be used.
+ */
+
+extern void kgdb_call_nmi_hook(void *ignored);
+
+/**
  *      kgdb_roundup_cpus - Get other CPUs into a holding pattern
- *      @flags: Current IRQ state
  *
  *      On SMP systems, we need to get the attention of the other CPUs
  *      and get them into a known state.  This should do what is needed
  *      to get the other CPUs to call kgdb_wait(). Note that on some arches,
- *      the NMI approach is not used for rounding up all the CPUs. For example,
- *      in case of MIPS, smp_call_function() is used to roundup CPUs. In
- *      this case, we have to make sure that interrupts are enabled before
- *      calling smp_call_function(). The argument to this function is
- *      the flags that will be used when restoring the interrupts. There is
- *      local_irq_save() call before kgdb_roundup_cpus().
+ *      the NMI approach is not used for rounding up all the CPUs.  Normally
+ *      those architectures can just not implement this and get the default.
  *
  *      On non-SMP systems, this is not called.
  */
-extern void kgdb_roundup_cpus(unsigned long flags);
+extern void kgdb_roundup_cpus(void);
 
 /**
  *      kgdb_arch_set_pc - Generic call back to the program counter
@@ -281,7 +287,7 @@ struct kgdb_io {
         int                     is_console;
 };
 
-extern struct kgdb_arch         arch_kgdb_ops;
+extern const struct kgdb_arch           arch_kgdb_ops;
 
 extern unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs);
 
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 65c0f1363788..5cc608de6883 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -55,6 +55,7 @@
 #include <linux/mm.h>
 #include <linux/vmacache.h>
 #include <linux/rcupdate.h>
+#include <linux/irq.h>
 
 #include <asm/cacheflush.h>
 #include <asm/byteorder.h>
@@ -220,6 +221,62 @@ int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
         return 0;
 }
 
+#ifdef CONFIG_SMP
+
+/*
+ * Default (weak) implementation for kgdb_roundup_cpus
+ */
+
+static DEFINE_PER_CPU(call_single_data_t, kgdb_roundup_csd);
+
+void __weak kgdb_call_nmi_hook(void *ignored)
+{
+        /*
+         * NOTE: get_irq_regs() is supposed to get the registers from
+         * before the IPI interrupt happened and so is supposed to
+         * show where the processor was.  In some situations it's
+         * possible we might be called without an IPI, so it might be
+         * safer to figure out how to make kgdb_breakpoint() work
+         * properly here.
+         */
+        kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
+}
+
+void __weak kgdb_roundup_cpus(void)
+{
+        call_single_data_t *csd;
+        int this_cpu = raw_smp_processor_id();
+        int cpu;
+        int ret;
+
+        for_each_online_cpu(cpu) {
+                /* No need to roundup ourselves */
+                if (cpu == this_cpu)
+                        continue;
+
+                csd = &per_cpu(kgdb_roundup_csd, cpu);
+
+                /*
+                 * If it didn't round up last time, don't try again
+                 * since smp_call_function_single_async() will block.
+                 *
+                 * If rounding_up is false then we know that the
+                 * previous call must have at least started and that
+                 * means smp_call_function_single_async() won't block.
+                 */
+                if (kgdb_info[cpu].rounding_up)
+                        continue;
+                kgdb_info[cpu].rounding_up = true;
+
+                csd->func = kgdb_call_nmi_hook;
+                ret = smp_call_function_single_async(cpu, csd);
+                if (ret)
+                        kgdb_info[cpu].rounding_up = false;
+        }
+}
+
+#endif
+
 /*
  * Some architectures need cache flushes when we set/clear a
  * breakpoint:
@@ -535,6 +592,8 @@ return_normal:
                                 arch_kgdb_ops.correct_hw_break();
                         if (trace_on)
                                 tracing_on();
+                        kgdb_info[cpu].debuggerinfo = NULL;
+                        kgdb_info[cpu].task = NULL;
                         kgdb_info[cpu].exception_state &=
                                 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
                         kgdb_info[cpu].enter_kgdb--;
@@ -593,7 +652,7 @@ return_normal:
 
         /* Signal the other CPUs to enter kgdb_wait() */
         else if ((!kgdb_single_step) && kgdb_do_roundup)
-                kgdb_roundup_cpus(flags);
+                kgdb_roundup_cpus();
 #endif
 
         /*
@@ -667,6 +726,8 @@ kgdb_restore:
         if (trace_on)
                 tracing_on();
 
+        kgdb_info[cpu].debuggerinfo = NULL;
+        kgdb_info[cpu].task = NULL;
         kgdb_info[cpu].exception_state &=
                 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
         kgdb_info[cpu].enter_kgdb--;
@@ -747,6 +808,8 @@ int kgdb_nmicallback(int cpu, void *regs)
         struct kgdb_state kgdb_var;
         struct kgdb_state *ks = &kgdb_var;
 
+        kgdb_info[cpu].rounding_up = false;
+
         memset(ks, 0, sizeof(struct kgdb_state));
         ks->cpu                 = cpu;
         ks->linux_regs          = regs;
diff --git a/kernel/debug/debug_core.h b/kernel/debug/debug_core.h
index 127d9bc49fb4..b4a7c326d546 100644
--- a/kernel/debug/debug_core.h
+++ b/kernel/debug/debug_core.h
@@ -42,6 +42,7 @@ struct debuggerinfo_struct {
         int                     ret_state;
         int                     irq_depth;
         int                     enter_kgdb;
+        bool                    rounding_up;
 };
 
 extern struct debuggerinfo_struct kgdb_info[];
diff --git a/kernel/debug/kdb/kdb_bt.c b/kernel/debug/kdb/kdb_bt.c
index 7921ae4fca8d..7e2379aa0a1e 100644
--- a/kernel/debug/kdb/kdb_bt.c
+++ b/kernel/debug/kdb/kdb_bt.c
@@ -186,7 +186,16 @@ kdb_bt(int argc, const char **argv)
                 kdb_printf("btc: cpu status: ");
                 kdb_parse("cpu\n");
                 for_each_online_cpu(cpu) {
-                        sprintf(buf, "btt 0x%px\n", KDB_TSK(cpu));
+                        void *kdb_tsk = KDB_TSK(cpu);
+
+                        /* If a CPU failed to round up we could be here */
+                        if (!kdb_tsk) {
+                                kdb_printf("WARNING: no task for cpu %ld\n",
+                                           cpu);
+                                continue;
+                        }
+
+                        sprintf(buf, "btt 0x%px\n", kdb_tsk);
                         kdb_parse(buf);
                         touch_nmi_watchdog();
                 }
diff --git a/kernel/debug/kdb/kdb_debugger.c b/kernel/debug/kdb/kdb_debugger.c
index 15e1a7af5dd0..53a0df6e4d92 100644
--- a/kernel/debug/kdb/kdb_debugger.c
+++ b/kernel/debug/kdb/kdb_debugger.c
@@ -118,13 +118,6 @@ int kdb_stub(struct kgdb_state *ks)
         kdb_bp_remove();
         KDB_STATE_CLEAR(DOING_SS);
         KDB_STATE_SET(PAGER);
-        /* zero out any offline cpu data */
-        for_each_present_cpu(i) {
-                if (!cpu_online(i)) {
-                        kgdb_info[i].debuggerinfo = NULL;
-                        kgdb_info[i].task = NULL;
-                }
-        }
         if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) {
                 ks->pass_exception = 1;
                 KDB_FLAG_SET(CATASTROPHIC);
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index d72b32c66f7d..82a3b32a7cfc 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -658,7 +658,7 @@ static void kdb_cmderror(int diag)
  */
 struct defcmd_set {
         int count;
-        int usable;
+        bool usable;
         char *name;
         char *usage;
         char *help;
@@ -666,7 +666,7 @@ struct defcmd_set {
 };
 static struct defcmd_set *defcmd_set;
 static int defcmd_set_count;
-static int defcmd_in_progress;
+static bool defcmd_in_progress;
 
 /* Forward references */
 static int kdb_exec_defcmd(int argc, const char **argv);
@@ -676,9 +676,9 @@ static int kdb_defcmd2(const char *cmdstr, const char *argv0)
         struct defcmd_set *s = defcmd_set + defcmd_set_count - 1;
         char **save_command = s->command;
         if (strcmp(argv0, "endefcmd") == 0) {
-                defcmd_in_progress = 0;
+                defcmd_in_progress = false;
                 if (!s->count)
-                        s->usable = 0;
+                        s->usable = false;
                 if (s->usable)
                         /* macros are always safe because when executed each
                          * internal command re-enters kdb_parse() and is
@@ -695,7 +695,7 @@ static int kdb_defcmd2(const char *cmdstr, const char *argv0)
         if (!s->command) {
                 kdb_printf("Could not allocate new kdb_defcmd table for %s\n",
                            cmdstr);
-                s->usable = 0;
+                s->usable = false;
                 return KDB_NOTIMP;
         }
         memcpy(s->command, save_command, s->count * sizeof(*(s->command)));
@@ -737,7 +737,7 @@ static int kdb_defcmd(int argc, const char **argv)
                defcmd_set_count * sizeof(*defcmd_set));
         s = defcmd_set + defcmd_set_count;
         memset(s, 0, sizeof(*s));
-        s->usable = 1;
+        s->usable = true;
         s->name = kdb_strdup(argv[1], GFP_KDB);
         if (!s->name)
                 goto fail_name;
@@ -756,7 +756,7 @@ static int kdb_defcmd(int argc, const char **argv)
                 s->help[strlen(s->help)-1] = '\0';
         }
         ++defcmd_set_count;
-        defcmd_in_progress = 1;
+        defcmd_in_progress = true;
         kfree(save_defcmd_set);
         return 0;
 fail_help: