[PATCH 1/2] add tunable_notifier function ,take4
Takenori Nagano
t-nagano at ah.jp.nec.com
Wed Apr 23 07:11:34 EDT 2008
This patch adds new notifier function tunable_notifier_chain. Its base is
atomic_notifier_chain.
Thanks,
---
Signed-off-by: Takenori Nagano <t-nagano at ah.jp.nec.com>
---
diff -uprN linux-2.6.25.orig/Documentation/ABI/testing/sysfs-notifiers linux-2.6.25/Documentation/ABI/testing/sysfs-notifiers
--- linux-2.6.25.orig/Documentation/ABI/testing/sysfs-notifiers 1970-01-01 09:00:00.000000000 +0900
+++ linux-2.6.25/Documentation/ABI/testing/sysfs-notifiers 2008-04-22 17:55:39.142310091 +0900
@@ -0,0 +1,15 @@
+What: /sys/kernel/notifiers/<notifier>/<notifier_block>/priority
+Date: April 2008
+Contact: Takenori Nagano <t-nagano at ah.jp.nec.com>
+Description:
+ The /sys/kernel/notifiers/<notifier>/<notifier_block>/priority
+ file controls notifier_block order on notifier. Writing to this
+ file will insert the notifier_block to appropriate place that is
+ pointed by new priority.
+
+What: /sys/kernel/notifiers/<notifier>/<notifier_block>/description
+Date: April 2008
+Contact: Takenori Nagano <t-nagano at ah.jp.nec.com>
+Description:
+ This file shows the description of the notifier_block that
+ belongs to. It helps to decide the priority value.
diff -uprN linux-2.6.25.orig/include/linux/kernel.h linux-2.6.25/include/linux/kernel.h
--- linux-2.6.25.orig/include/linux/kernel.h 2008-04-22 20:35:01.239466758 +0900
+++ linux-2.6.25/include/linux/kernel.h 2008-04-21 17:15:59.072648972 +0900
@@ -129,7 +129,7 @@ extern int _cond_resched(void);
(__x < 0) ? -__x : __x; \
})
-extern struct atomic_notifier_head panic_notifier_list;
+extern struct tunable_atomic_notifier_head panic_notifier_list;
extern long (*panic_blink)(long time);
NORET_TYPE void panic(const char * fmt, ...)
__attribute__ ((NORET_AND format (printf, 1, 2))) __cold;
diff -uprN linux-2.6.25.orig/include/linux/notifier.h linux-2.6.25/include/linux/notifier.h
--- linux-2.6.25.orig/include/linux/notifier.h 2008-04-22 20:35:01.543464904 +0900
+++ linux-2.6.25/include/linux/notifier.h 2008-04-21 17:15:59.112641471 +0900
@@ -13,6 +13,7 @@
#include <linux/mutex.h>
#include <linux/rwsem.h>
#include <linux/srcu.h>
+#include <linux/kobject.h>
/*
* Notifier chains are of four types:
@@ -53,6 +54,13 @@ struct notifier_block {
int priority;
};
+struct tunable_atomic_notifier_block {
+ struct notifier_block *nb;
+ struct tunable_atomic_notifier_head *head;
+ struct kobject kobj;
+ char *desc;
+};
+
struct atomic_notifier_head {
spinlock_t lock;
struct notifier_block *head;
@@ -63,6 +71,13 @@ struct blocking_notifier_head {
struct notifier_block *head;
};
+struct tunable_atomic_notifier_head {
+ spinlock_t lock;
+ struct notifier_block *head;
+ char *name;
+ struct kset *notifier_sub_kset;
+};
+
struct raw_notifier_head {
struct notifier_block *head;
};
@@ -73,6 +88,13 @@ struct srcu_notifier_head {
struct notifier_block *head;
};
+struct control_file_info {
+ struct tunable_atomic_notifier_head *nh;
+ struct tunable_atomic_notifier_block *n;
+ char *name;
+ struct control_file_info *next;
+};
+
#define ATOMIC_INIT_NOTIFIER_HEAD(name) do { \
spin_lock_init(&(name)->lock); \
(name)->head = NULL; \
@@ -81,6 +103,12 @@ struct srcu_notifier_head {
init_rwsem(&(name)->rwsem); \
(name)->head = NULL; \
} while (0)
+#define TUNABLE_ATOMIC_INIT_NOTIFIER(val1, val2) do { \
+ spin_lock_init(&(val1)->lock); \
+ (val1)->head = NULL; \
+ (val1)->name = val2; \
+ (val1)->notifier_sub_kset = NULL; \
+ } while (0)
#define RAW_INIT_NOTIFIER_HEAD(name) do { \
(name)->head = NULL; \
} while (0)
@@ -96,6 +124,11 @@ extern void srcu_init_notifier_head(stru
#define BLOCKING_NOTIFIER_INIT(name) { \
.rwsem = __RWSEM_INITIALIZER((name).rwsem), \
.head = NULL }
+#define TUNABLE_ATOMIC_NOTIFIER_INIT(val1, val2) { \
+ .lock =__SPIN_LOCK_UNLOCKED(val1.lock), \
+ .head = NULL, \
+ .name = val2, \
+ .notifier_sub_kset = NULL }
#define RAW_NOTIFIER_INIT(name) { \
.head = NULL }
/* srcu_notifier_heads cannot be initialized statically */
@@ -106,6 +139,9 @@ extern void srcu_init_notifier_head(stru
#define BLOCKING_NOTIFIER_HEAD(name) \
struct blocking_notifier_head name = \
BLOCKING_NOTIFIER_INIT(name)
+#define TUNABLE_ATOMIC_NOTIFIER_HEAD(name, val) \
+ struct tunable_atomic_notifier_head name = \
+ TUNABLE_ATOMIC_NOTIFIER_INIT(name, val)
#define RAW_NOTIFIER_HEAD(name) \
struct raw_notifier_head name = \
RAW_NOTIFIER_INIT(name)
@@ -116,6 +152,10 @@ extern int atomic_notifier_chain_registe
struct notifier_block *nb);
extern int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
struct notifier_block *nb);
+extern int tunable_atomic_notifier_chain_register(
+ struct tunable_atomic_notifier_head *nh,
+ struct tunable_atomic_notifier_block *nb,
+ char *name, char *desc);
extern int raw_notifier_chain_register(struct raw_notifier_head *nh,
struct notifier_block *nb);
extern int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
@@ -129,6 +169,9 @@ extern int atomic_notifier_chain_unregis
struct notifier_block *nb);
extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
struct notifier_block *nb);
+extern int tunable_atomic_notifier_chain_unregister(
+ struct tunable_atomic_notifier_head *nh,
+ struct tunable_atomic_notifier_block *nb);
extern int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
struct notifier_block *nb);
extern int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
@@ -142,6 +185,14 @@ extern int blocking_notifier_call_chain(
unsigned long val, void *v);
extern int __blocking_notifier_call_chain(struct blocking_notifier_head *nh,
unsigned long val, void *v, int nr_to_call, int *nr_calls);
+extern int tunable_atomic_notifier_call_chain(
+ struct tunable_atomic_notifier_head *nh,
+ unsigned long val, void *v);
+extern int __tunable_atomic_notifier_call_chain(
+ struct tunable_atomic_notifier_head *nh,
+ unsigned long val, void *v,
+ int nr_to_call, int *nr_calls);
+extern int tunable_atomic_notifier_init(void);
extern int raw_notifier_call_chain(struct raw_notifier_head *nh,
unsigned long val, void *v);
extern int __raw_notifier_call_chain(struct raw_notifier_head *nh,
diff -uprN linux-2.6.25.orig/kernel/ksysfs.c linux-2.6.25/kernel/ksysfs.c
--- linux-2.6.25.orig/kernel/ksysfs.c 2008-04-17 11:49:44.000000000 +0900
+++ linux-2.6.25/kernel/ksysfs.c 2008-04-21 17:15:59.136648497 +0900
@@ -15,6 +15,7 @@
#include <linux/init.h>
#include <linux/kexec.h>
#include <linux/sched.h>
+#include <linux/notifier.h>
#define KERNEL_ATTR_RO(_name) \
static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
@@ -146,7 +147,10 @@ static int __init ksysfs_init(void)
if (error)
goto notes_exit;
- return 0;
+ /* create the /sys/kernel/notifiers directory */
+ error = tunable_atomic_notifier_init();
+
+ return error;
notes_exit:
if (notes_size > 0)
diff -uprN linux-2.6.25.orig/kernel/notifier.c linux-2.6.25/kernel/notifier.c
--- linux-2.6.25.orig/kernel/notifier.c 2008-04-22 20:35:03.131455216 +0900
+++ linux-2.6.25/kernel/notifier.c 2008-04-21 17:15:59.172648342 +0900
@@ -319,6 +319,261 @@ int blocking_notifier_call_chain(struct
EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);
/*
+ * Tunable atomic notifier chain routines. Registration and unregistration
+ * use a spinlock, and call_chain is synchronized by RCU (no locks).
+ * User can change the list order to use /sys/kernel/notifiers/list-name/.
+ */
+
+static ssize_t priority_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct tunable_atomic_notifier_block *n = container_of(kobj,
+ struct tunable_atomic_notifier_block, kobj);
+
+ return sprintf(buf, "%d\n", n->nb->priority);
+}
+
+static ssize_t priority_store(struct kobject *kobj,
+ struct kobj_attribute *attr, const char *buf, size_t size)
+{
+ struct tunable_atomic_notifier_block *n = container_of(kobj,
+ struct tunable_atomic_notifier_block, kobj);
+ struct tunable_atomic_notifier_head *nh = n->head;
+ unsigned long flags;
+ int priority, ret;
+
+ sscanf(buf, "%d", &priority);
+ n->nb->priority = priority;
+
+ spin_lock_irqsave(&nh->lock, flags);
+ ret = notifier_chain_unregister(&nh->head, n->nb);
+ if (ret)
+ goto out_unlock;
+ ret = notifier_chain_register(&nh->head, n->nb);
+
+out_unlock:
+ spin_unlock_irqrestore(&nh->lock, flags);
+
+ return (ret ? ret : size);
+
+}
+
+static ssize_t description_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct tunable_atomic_notifier_block *n = container_of(kobj,
+ struct tunable_atomic_notifier_block, kobj);
+
+ if (n->desc)
+ return sprintf(buf, "%s\n", n->desc);
+
+ return sprintf(buf, "Description is not available\n");
+}
+
+static struct kobj_attribute priority_attr =
+ __ATTR(priority, 0644, priority_show, priority_store);
+static struct kobj_attribute description_attr =
+ __ATTR_RO(description);
+
+static struct attribute *notifiers_attributes[] = {
+ &priority_attr.attr, &description_attr.attr, NULL
+};
+
+static struct kobj_type notifiers_ktype = {
+ .sysfs_ops = &kobj_sysfs_ops,
+ .default_attrs = notifiers_attributes,
+};
+
+static struct kobject *notifiers_kobj;
+struct control_file_info *base;
+
+int notifiers_kobject_create(struct tunable_atomic_notifier_head *nh,
+ struct tunable_atomic_notifier_block *n, char *name)
+{
+ int error = -ENOMEM;
+ struct kobject *kobj = &n->kobj;
+
+ if (!nh->notifier_sub_kset) {
+ nh->notifier_sub_kset = kset_create_and_add(nh->name, NULL,
+ notifiers_kobj);
+ if (!nh->notifier_sub_kset)
+ goto out;
+ }
+
+ memset(kobj, 0, sizeof(struct kobject));
+ kobj->kset = nh->notifier_sub_kset;
+ error = kobject_init_and_add(kobj, ¬ifiers_ktype, NULL, "%s", name);
+ if (error)
+ kobject_put(kobj);
+
+out:
+ return error;
+}
+
+/**
+ * tunable_atomic_notifier_chain_register - Add notifier to an tunable notifier chain
+ * @nh: Pointer to head of the tunable notifier chain
+ * @n: New entry in notifier chain
+ * @name: Pointer to the name of the new notifier entry
+ * @desc: Pointer to the description of new entry
+ *
+ * Adds a notifier to an tunable notifier chain and makes control dir.
+ * This function must be called after kmem_cache_init().
+ *
+ * Returns zero on success or %-ENODEV on failure.
+ */
+
+int tunable_atomic_notifier_chain_register(
+ struct tunable_atomic_notifier_head *nh,
+ struct tunable_atomic_notifier_block *n, char *name, char *desc)
+{
+ unsigned long flags;
+ int ret;
+
+ if (!name)
+ return -EINVAL;
+ if (desc)
+ n->desc = desc;
+
+ if (!notifiers_kobj) {
+ struct control_file_info *temp, *new;
+
+ temp = kmalloc(sizeof(struct control_file_info), GFP_ATOMIC);
+ if (!temp)
+ return -ENOMEM;
+ temp->nh = nh;
+ temp->n = n;
+ temp->name = name;
+ temp->next = NULL;
+ if (!base)
+ base = temp;
+ else {
+ new = base;
+ while (new->next) {
+ new = new->next;
+ }
+ new->next = temp;
+ }
+ goto regist;
+ }
+
+ ret = notifiers_kobject_create(nh, n, name);
+ if (ret)
+ return ret;
+
+regist:
+ spin_lock_irqsave(&nh->lock, flags);
+ ret = notifier_chain_register(&nh->head, n->nb);
+ spin_unlock_irqrestore(&nh->lock, flags);
+ n->head = nh;
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(tunable_atomic_notifier_chain_register);
+
+/**
+ * tunable_atomic_notifier_chain_unregister - Remove notifier from a tunable notifier chain
+ * @nh: Pointer to head of the tunable notifier chain
+ * @n: Entry to remove from notifier chain
+ *
+ * Removes a notifier from a tunable notifier chain.
+ *
+ * Retunrns zero on success or %-ENOENT on failure.
+ */
+
+int tunable_atomic_notifier_chain_unregister(
+ struct tunable_atomic_notifier_head *nh,
+ struct tunable_atomic_notifier_block *n)
+{
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&nh->lock, flags);
+ ret = notifier_chain_unregister(&nh->head, n->nb);
+ spin_unlock_irqrestore(&nh->lock, flags);
+ synchronize_rcu();
+
+ if (ret)
+ return ret;
+
+ kobject_del(&n->kobj);
+ kobject_put(&n->kobj);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tunable_atomic_notifier_chain_unregister);
+
+/**
+ * __tunable_atomic_notifier_call_chain - Call functions in a tunable notifier chain
+ * @nh: Pointer to head of the tunable notifier chain
+ * @val: Value passed unmodified to notifier function
+ * @v: Pointer passed unmodified to notifier function
+ * @nr_to_call: See the comment for notifier_call_chain
+ * @nr_calls: See the comment for notifier_call_chain
+ *
+ * Calls each function in a notifier chain in turn. The functions
+ * run in an atomic context, so they must not block.
+ * This routine uses RCU to synchronize with changes to the chain.
+ *
+ * If the return value of the notifier can be and'ed
+ * with %NOTIFY_STOP_MASK then tunable_atomic_notifier_call_chain()
+ * will return immediately, with the return value of
+ * the notifier function which halted execution.
+ * Otherwise the return value is the return value
+ * of the last notifier function called.
+ */
+
+int __kprobes __tunable_atomic_notifier_call_chain(
+ struct tunable_atomic_notifier_head *nh,
+ unsigned long val, void *v,
+ int nr_to_call, int *nr_calls)
+{
+ int ret;
+
+ rcu_read_lock();
+ ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
+ rcu_read_unlock();
+ return ret;
+}
+EXPORT_SYMBOL_GPL(__tunable_atomic_notifier_call_chain);
+
+int __kprobes tunable_atomic_notifier_call_chain(
+ struct tunable_atomic_notifier_head *nh,
+ unsigned long val, void *v)
+{
+ return __tunable_atomic_notifier_call_chain(nh, val, v, -1, NULL);
+}
+EXPORT_SYMBOL_GPL(tunable_atomic_notifier_call_chain);
+
+int __init tunable_atomic_notifier_init(void) {
+ struct control_file_info *prev, *temp = base;
+ struct tunable_atomic_notifier_head *nh;
+ struct tunable_atomic_notifier_block *n;
+ char *name;
+ int error;
+
+ notifiers_kobj = kobject_create_and_add("notifiers", kernel_kobj);
+
+ if (!notifiers_kobj)
+ return -ENOMEM;
+
+ while (temp) {
+ nh = temp->nh;
+ n = temp->n;
+ name = temp->name;
+
+ error = notifiers_kobject_create(nh, n, name);
+ if (error)
+ printk("%s: %s is failed to create. err = %d\n",
+ nh->name, name, error);
+ prev = temp;
+ temp = temp->next;
+ kfree(prev);
+ }
+ return 0;
+}
+
+/*
* Raw notifier chain routines. There is no protection;
* the caller must provide it. Use at your own risk!
*/
diff -uprN linux-2.6.25.orig/kernel/panic.c linux-2.6.25/kernel/panic.c
--- linux-2.6.25.orig/kernel/panic.c 2008-04-22 20:35:03.147454771 +0900
+++ linux-2.6.25/kernel/panic.c 2008-04-21 17:15:59.208648222 +0900
@@ -30,7 +30,7 @@ static DEFINE_SPINLOCK(pause_on_oops_loc
int panic_timeout;
-ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
+TUNABLE_ATOMIC_NOTIFIER_HEAD(panic_notifier_list, "panic_notifier_list");
EXPORT_SYMBOL(panic_notifier_list);
@@ -101,7 +101,7 @@ NORET_TYPE void panic(const char * fmt,
smp_send_stop();
#endif
- atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
+ tunable_atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
if (!panic_blink)
panic_blink = no_blink;
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