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Subject[PATCH 10/10] intel_cacheinfo: fix cpu hotplug error handling
- Fix resource leakage in error case within detect_cache_attributes()

- Introduce cache_dev_map cpumask to track whether cache interface for
CPU is successfully added by cache_add_dev() or not.

cache_add_dev() may fail with out of memory error. In order to
avoid cache_remove_dev() with that uninitialized cache interface when
CPU_DEAD event is delivered we need to have the cache_dev_map cpumask.

(We cannot change cache_add_dev() from CPU_ONLINE event handler
to CPU_UP_PREPARE event handler. Because cache_add_dev() needs
to do cpuid and store the results with its CPU online.)

Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

---
arch/i386/kernel/cpu/intel_cacheinfo.c | 57 +++++++++++++++++++++++----------
1 file changed, 40 insertions(+), 17 deletions(-)
Index: 2.6-mm/arch/i386/kernel/cpu/intel_cacheinfo.c
===================================================================
--- 2.6-mm.orig/arch/i386/kernel/cpu/intel_cacheinfo.c
+++ 2.6-mm/arch/i386/kernel/cpu/intel_cacheinfo.c
@@ -502,6 +502,11 @@ static void __init cache_remove_shared_c

static void free_cache_attributes(unsigned int cpu)
{
+ int i;
+
+ for (i = 0; i < num_cache_leaves; i++)
+ cache_remove_shared_cpu_map(cpu, i);
+
kfree(cpuid4_info[cpu]);
cpuid4_info[cpu] = NULL;
}
@@ -509,8 +514,8 @@ static void free_cache_attributes(unsign
static int __cpuinit detect_cache_attributes(unsigned int cpu)
{
struct _cpuid4_info *this_leaf;
- unsigned long j;
- int retval;
+ unsigned long j;
+ int retval;
cpumask_t oldmask;

if (num_cache_leaves == 0)
@@ -527,19 +532,26 @@ static int __cpuinit detect_cache_attrib
goto out;

/* Do cpuid and store the results */
- retval = 0;
for (j = 0; j < num_cache_leaves; j++) {
this_leaf = CPUID4_INFO_IDX(cpu, j);
retval = cpuid4_cache_lookup(j, this_leaf);
- if (unlikely(retval < 0))
+ if (unlikely(retval < 0)) {
+ int i;
+
+ for (i = 0; i < j; i++)
+ cache_remove_shared_cpu_map(cpu, i);
break;
+ }
cache_shared_cpu_map_setup(cpu, j);
}
set_cpus_allowed(current, oldmask);

out:
- if (retval)
- free_cache_attributes(cpu);
+ if (retval) {
+ kfree(cpuid4_info[cpu]);
+ cpuid4_info[cpu] = NULL;
+ }
+
return retval;
}

@@ -683,13 +695,14 @@ static void cpuid4_cache_sysfs_exit(unsi

static int __cpuinit cpuid4_cache_sysfs_init(unsigned int cpu)
{
+ int err;

if (num_cache_leaves == 0)
return -ENOENT;

- detect_cache_attributes(cpu);
- if (cpuid4_info[cpu] == NULL)
- return -ENOENT;
+ err = detect_cache_attributes(cpu);
+ if (err)
+ return err;

/* Allocate all required memory */
cache_kobject[cpu] = kzalloc(sizeof(struct kobject), GFP_KERNEL);
@@ -708,13 +721,15 @@ err_out:
return -ENOMEM;
}

+static cpumask_t cache_dev_map = CPU_MASK_NONE;
+
/* Add/Remove cache interface for CPU device */
static int __cpuinit cache_add_dev(struct sys_device * sys_dev)
{
unsigned int cpu = sys_dev->id;
unsigned long i, j;
struct _index_kobject *this_object;
- int retval = 0;
+ int retval;

retval = cpuid4_cache_sysfs_init(cpu);
if (unlikely(retval < 0))
@@ -724,6 +739,10 @@ static int __cpuinit cache_add_dev(struc
kobject_set_name(cache_kobject[cpu], "%s", "cache");
cache_kobject[cpu]->ktype = &ktype_percpu_entry;
retval = kobject_register(cache_kobject[cpu]);
+ if (retval < 0) {
+ cpuid4_cache_sysfs_exit(cpu);
+ return retval;
+ }

for (i = 0; i < num_cache_leaves; i++) {
this_object = INDEX_KOBJECT_PTR(cpu,i);
@@ -743,6 +762,9 @@ static int __cpuinit cache_add_dev(struc
break;
}
}
+ if (!retval)
+ cpu_set(cpu, cache_dev_map);
+
return retval;
}

@@ -751,13 +773,14 @@ static void __cpuinit cache_remove_dev(s
unsigned int cpu = sys_dev->id;
unsigned long i;

- for (i = 0; i < num_cache_leaves; i++) {
- cache_remove_shared_cpu_map(cpu, i);
+ if (!cpu_isset(cpu, cache_dev_map))
+ return;
+ cpu_clear(cpu, cache_dev_map);
+
+ for (i = 0; i < num_cache_leaves; i++)
kobject_unregister(&(INDEX_KOBJECT_PTR(cpu,i)->kobj));
- }
kobject_unregister(cache_kobject[cpu]);
cpuid4_cache_sysfs_exit(cpu);
- return;
}

static int __cpuinit cacheinfo_cpu_callback(struct notifier_block *nfb,
@@ -782,7 +805,7 @@ static int __cpuinit cacheinfo_cpu_callb

static struct notifier_block __cpuinitdata cacheinfo_cpu_notifier =
{
- .notifier_call = cacheinfo_cpu_callback,
+ .notifier_call = cacheinfo_cpu_callback,
};

static int __cpuinit cache_sysfs_init(void)
@@ -795,8 +818,8 @@ static int __cpuinit cache_sysfs_init(vo
register_hotcpu_notifier(&cacheinfo_cpu_notifier);

for_each_online_cpu(i) {
- cacheinfo_cpu_callback(&cacheinfo_cpu_notifier, CPU_ONLINE,
- (void *)(long)i);
+ struct sys_device *sys_dev = get_cpu_sysdev(i);
+ cache_add_dev(sys_dev);
}

return 0;
-
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