[IA64] kdump: Short path to freeze CPUs

Setting monarch_cpu = -1 to let slaves frozen might not work, because
there might be slaves being late, not entered the rendezvous yet.
Such slaves might be caught in while (monarch_cpu == -1) loop.

Use kdump_in_progress instead of monarch_cpus to break INIT rendezvous
and let all slaves enter DIE_INIT_SLAVE_LEAVE smoothly.

And monarch no longer need to manage rendezvous if once kdump_in_progress
is set, catch the monarch in DIE_INIT_MONARCH_ENTER then.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Haren Myneni <hbabu@us.ibm.com>
Cc: kexec@lists.infradead.org
Acked-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

diff --git a/arch/ia64/kernel/crash.c b/arch/ia64/kernel/crash.c
index 0995fdc..6631a9d 100644 (file)
--- a/arch/ia64/kernel/crash.c
+++ b/arch/ia64/kernel/crash.c
@@ -127,14 +127,13 @@ machine_crash_shutdown(struct pt_regs *pt)
         * If an INIT is asserted here:
         * - All receivers might be slaves, since some of cpus could already
         *   be frozen and INIT might be masked on monarch.  In this case,
-        *   all slaves will park in while (monarch_cpu == -1) loop before
-        *   DIE_INIT_SLAVE_ENTER that for waiting monarch enters.
-        *      => TBD: freeze all slaves
+        *   all slaves will be frozen soon since kdump_in_progress will let
+        *   them into DIE_INIT_SLAVE_LEAVE.
         * - One might be a monarch, but INIT rendezvous will fail since
         *   at least this cpu already have INIT masked so it never join
         *   to the rendezvous.  In this case, all slaves and monarch will
-        *   be frozen after timeout of the INIT rendezvous.
-        *      => TBD: freeze them without waiting timeout
+        *   be frozen soon with no wait since the INIT rendezvous is skipped
+        *   by kdump_in_progress.
         */
        kdump_smp_send_stop();
        /* not all cpu response to IPI, send INIT to freeze them */
@@ -187,6 +186,7 @@ kdump_init_notifier(struct notifier_block *self, unsigned long val, void *data)
                                break;
                        /* fall through */
                case DIE_INIT_SLAVE_LEAVE:
+               case DIE_INIT_MONARCH_ENTER:
                case DIE_MCA_RENDZVOUS_LEAVE:
                        unw_init_running(kdump_cpu_freeze, NULL);
                        break;
@@ -217,7 +217,6 @@ kdump_init_notifier(struct notifier_block *self, unsigned long val, void *data)
                if (kdump_on_init && (nd->sos->rv_rc != 1)) {
                        if (atomic_inc_return(&kdump_in_progress) != 1)
                                kdump_freeze_monarch = 1;
-                       *(nd->monarch_cpu) = -1;
                }
                break;
        case DIE_INIT_MONARCH_LEAVE:
@@ -228,10 +227,8 @@ kdump_init_notifier(struct notifier_block *self, unsigned long val, void *data)
        case DIE_MCA_MONARCH_LEAVE:
                /* *(nd->data) indicate if MCA is recoverable */
                if (kdump_on_fatal_mca && !(*(nd->data))) {
-                       if (atomic_inc_return(&kdump_in_progress) == 1) {
-                               *(nd->monarch_cpu) = -1;
+                       if (atomic_inc_return(&kdump_in_progress) == 1)
                                machine_kdump_on_init();
-                       }
                        /* We got fatal MCA while kdump!? No way!! */
                }
                break;

diff --git a/arch/ia64/kernel/mca.c b/arch/ia64/kernel/mca.c
index 7b30d21..d2877a7 100644 (file)
--- a/arch/ia64/kernel/mca.c
+++ b/arch/ia64/kernel/mca.c
@@ -1682,14 +1682,25 @@ ia64_init_handler(struct pt_regs *regs, struct switch_stack *sw,
 
        if (!sos->monarch) {
                ia64_mc_info.imi_rendez_checkin[cpu] = IA64_MCA_RENDEZ_CHECKIN_INIT;
+
+#ifdef CONFIG_KEXEC
+               while (monarch_cpu == -1 && !atomic_read(&kdump_in_progress))
+                       udelay(1000);
+#else
                while (monarch_cpu == -1)
-                      cpu_relax();     /* spin until monarch enters */
+                       cpu_relax();    /* spin until monarch enters */
+#endif
 
                NOTIFY_INIT(DIE_INIT_SLAVE_ENTER, regs, (long)&nd, 1);
                NOTIFY_INIT(DIE_INIT_SLAVE_PROCESS, regs, (long)&nd, 1);
 
+#ifdef CONFIG_KEXEC
+               while (monarch_cpu != -1 && !atomic_read(&kdump_in_progress))
+                       udelay(1000);
+#else
                while (monarch_cpu != -1)
-                      cpu_relax();     /* spin until monarch leaves */
+                       cpu_relax();    /* spin until monarch leaves */
+#endif
 
                NOTIFY_INIT(DIE_INIT_SLAVE_LEAVE, regs, (long)&nd, 1);