[PATCH 7/7] ia64, kdump: Short path to freeze CPUs

Hidetoshi Seto
2009-06-18T06:53:23Z

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
---
arch/ia64/kernel/crash.c | 15 ++++++---------
arch/ia64/kernel/mca.c | 15 +++++++++++++--
2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/arch/ia64/kernel/crash.c b/arch/ia64/kernel/crash.c
index f43eccf..cf833af 100644
--- a/arch/ia64/kernel/crash.c
+++ b/arch/ia64/kernel/crash.c
@@ -129,14 +129,13 @@ 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 */
@@ -189,6 +188,7 @@ 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;
@@ -219,7 +219,6 @@ 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:
@@ -230,10 +229,8 @@ 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 8f33a88..7a34c6c 100644
--- 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);