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Subject[patch -mm] call cpu_chain with CPU_DOWN_FAILED if CPU_DOWN_PREPARE failed
From: Heiko Carstens <heiko.carstens@de.ibm.com>

This makes cpu hotplug symmetrical: if CPU_UP_PREPARE fails we get
CPU_UP_CANCELED, so we can undo what ever happened on PREPARE.
The same should happen for CPU_DOWN_PREPARE.

Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Gautham Shenoy <ego@in.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
---
kernel/cpu.c | 17 +++++++++--------
1 files changed, 9 insertions(+), 8 deletions(-)

Index: linux-2.6.20-rc3-mm1/kernel/cpu.c
===================================================================
--- linux-2.6.20-rc3-mm1.orig/kernel/cpu.c
+++ linux-2.6.20-rc3-mm1/kernel/cpu.c
@@ -122,9 +122,10 @@ static int take_cpu_down(void *unused)
/* Requires cpu_add_remove_lock to be held */
static int _cpu_down(unsigned int cpu)
{
- int err;
+ int err, nr_calls = 0;
struct task_struct *p;
cpumask_t old_allowed, tmp;
+ void *hcpu = (void *)(long)cpu;

if (num_online_cpus() == 1)
return -EBUSY;
@@ -132,11 +133,12 @@ static int _cpu_down(unsigned int cpu)
if (!cpu_online(cpu))
return -EINVAL;

- raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE,
- (void *)(long)cpu);
- err = raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
- (void *)(long)cpu);
+ raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
+ err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
+ hcpu, -1, &nr_calls);
if (err == NOTIFY_BAD) {
+ __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED, hcpu,
+ nr_calls, NULL);
printk("%s: attempt to take down CPU %u failed\n",
__FUNCTION__, cpu);
err = -EINVAL;
@@ -156,7 +158,7 @@ static int _cpu_down(unsigned int cpu)
if (IS_ERR(p) || cpu_online(cpu)) {
/* CPU didn't die: tell everyone. Can't complain. */
if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
- (void *)(long)cpu) == NOTIFY_BAD)
+ hcpu) == NOTIFY_BAD)
BUG();

if (IS_ERR(p)) {
@@ -178,8 +180,7 @@ static int _cpu_down(unsigned int cpu)
put_cpu();

/* CPU is completely dead: tell everyone. Too late to complain. */
- if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD,
- (void *)(long)cpu) == NOTIFY_BAD)
+ if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD, hcpu) == NOTIFY_BAD)
BUG();

check_for_tasks(cpu);
-
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