cpu hotplug: intel_cacheinfo: fix cpu hotplug error handling

- Fix resource leakage in error case within detect_cache_attributes()

- Don't register hotcpu notifier when cache_add_dev() returns error

- 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.)

[nix.or.die@googlemail.com: fix a section mismatch warning]
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Andi Kleen <ak@suse.de>
Cc: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Gabriel Craciunescu <nix.or.die@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
index 1826395..297a241 100644 (file)
--- a/arch/x86/kernel/cpu/intel_cacheinfo.c
+++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
@@ -499,6 +499,11 @@ static void __cpuinit cache_remove_shared_cpu_map(unsigned int cpu, int index) {
 
 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;
 }
@@ -506,8 +511,8 @@ static void free_cache_attributes(unsigned int cpu)
 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)
@@ -524,19 +529,26 @@ static int __cpuinit detect_cache_attributes(unsigned int cpu)
                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;
 }
 
@@ -669,7 +681,7 @@ static struct kobj_type ktype_percpu_entry = {
        .sysfs_ops      = &sysfs_ops,
 };
 
-static void cpuid4_cache_sysfs_exit(unsigned int cpu)
+static void __cpuinit cpuid4_cache_sysfs_exit(unsigned int cpu)
 {
        kfree(cache_kobject[cpu]);
        kfree(index_kobject[cpu]);
@@ -680,13 +692,14 @@ static void cpuid4_cache_sysfs_exit(unsigned int cpu)
 
 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);
@@ -705,13 +718,15 @@ 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))
@@ -721,6 +736,10 @@ static int __cpuinit cache_add_dev(struct sys_device * sys_dev)
        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);
@@ -740,6 +759,9 @@ static int __cpuinit cache_add_dev(struct sys_device * sys_dev)
                        break;
                }
        }
+       if (!retval)
+               cpu_set(cpu, cache_dev_map);
+
        return retval;
 }
 
@@ -750,13 +772,14 @@ static void __cpuinit cache_remove_dev(struct sys_device * sys_dev)
 
        if (cpuid4_info[cpu] == NULL)
                return;
-       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,
@@ -781,7 +804,7 @@ static int __cpuinit cacheinfo_cpu_callback(struct notifier_block *nfb,
 
 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)
@@ -791,14 +814,15 @@ static int __cpuinit cache_sysfs_init(void)
        if (num_cache_leaves == 0)
                return 0;
 
-       register_hotcpu_notifier(&cacheinfo_cpu_notifier);
-
        for_each_online_cpu(i) {
-               struct sys_device *sys_dev = get_cpu_sysdev((unsigned int)i);
+               int err;
+               struct sys_device *sys_dev = get_cpu_sysdev(i);
 
-               cache_add_dev(sys_dev);
+               err = cache_add_dev(sys_dev);
+               if (err)
+                       return err;
        }
-
+       register_hotcpu_notifier(&cacheinfo_cpu_notifier);
        return 0;
 }