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xianfeng |
#include <linux/kdebug.h>
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#include <linux/kprobes.h>
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#include <linux/module.h>
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#include <linux/notifier.h>
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#include <linux/rcupdate.h>
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#include <linux/vmalloc.h>
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/*
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* Notifier list for kernel code which wants to be called
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* at shutdown. This is used to stop any idling DMA operations
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* and the like.
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*/
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BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);
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/*
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* Notifier chain core routines. The exported routines below
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* are layered on top of these, with appropriate locking added.
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*/
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static int notifier_chain_register(struct notifier_block **nl,
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struct notifier_block *n)
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{
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while ((*nl) != NULL) {
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if (n->priority > (*nl)->priority)
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break;
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nl = &((*nl)->next);
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}
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n->next = *nl;
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rcu_assign_pointer(*nl, n);
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return 0;
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}
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static int notifier_chain_unregister(struct notifier_block **nl,
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struct notifier_block *n)
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{
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while ((*nl) != NULL) {
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if ((*nl) == n) {
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rcu_assign_pointer(*nl, n->next);
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return 0;
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}
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nl = &((*nl)->next);
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}
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return -ENOENT;
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}
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/**
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* notifier_call_chain - Informs the registered notifiers about an event.
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* @nl: Pointer to head of the blocking notifier chain
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* @val: Value passed unmodified to notifier function
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* @v: Pointer passed unmodified to notifier function
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* @nr_to_call: Number of notifier functions to be called. Don't care
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* value of this parameter is -1.
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* @nr_calls: Records the number of notifications sent. Don't care
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* value of this field is NULL.
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* @returns: notifier_call_chain returns the value returned by the
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* last notifier function called.
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*/
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static int __kprobes notifier_call_chain(struct notifier_block **nl,
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unsigned long val, void *v,
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int nr_to_call, int *nr_calls)
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{
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int ret = NOTIFY_DONE;
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struct notifier_block *nb, *next_nb;
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nb = rcu_dereference(*nl);
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while (nb && nr_to_call) {
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next_nb = rcu_dereference(nb->next);
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ret = nb->notifier_call(nb, val, v);
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if (nr_calls)
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(*nr_calls)++;
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if ((ret & NOTIFY_STOP_MASK) == NOTIFY_STOP_MASK)
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break;
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nb = next_nb;
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nr_to_call--;
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}
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return ret;
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}
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/*
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* Atomic notifier chain routines. Registration and unregistration
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* use a spinlock, and call_chain is synchronized by RCU (no locks).
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*/
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/**
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* atomic_notifier_chain_register - Add notifier to an atomic notifier chain
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* @nh: Pointer to head of the atomic notifier chain
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* @n: New entry in notifier chain
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*
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* Adds a notifier to an atomic notifier chain.
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*
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* Currently always returns zero.
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*/
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int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
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struct notifier_block *n)
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{
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unsigned long flags;
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int ret;
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spin_lock_irqsave(&nh->lock, flags);
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ret = notifier_chain_register(&nh->head, n);
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spin_unlock_irqrestore(&nh->lock, flags);
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return ret;
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}
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EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);
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/**
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* atomic_notifier_chain_unregister - Remove notifier from an atomic notifier chain
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* @nh: Pointer to head of the atomic notifier chain
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* @n: Entry to remove from notifier chain
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*
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* Removes a notifier from an atomic notifier chain.
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*
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* Returns zero on success or %-ENOENT on failure.
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*/
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int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
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struct notifier_block *n)
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{
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unsigned long flags;
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int ret;
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spin_lock_irqsave(&nh->lock, flags);
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ret = notifier_chain_unregister(&nh->head, n);
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spin_unlock_irqrestore(&nh->lock, flags);
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synchronize_rcu();
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return ret;
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}
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EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);
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/**
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* __atomic_notifier_call_chain - Call functions in an atomic notifier chain
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* @nh: Pointer to head of the atomic notifier chain
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* @val: Value passed unmodified to notifier function
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* @v: Pointer passed unmodified to notifier function
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* @nr_to_call: See the comment for notifier_call_chain.
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* @nr_calls: See the comment for notifier_call_chain.
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*
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140 |
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* Calls each function in a notifier chain in turn. The functions
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* run in an atomic context, so they must not block.
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* This routine uses RCU to synchronize with changes to the chain.
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*
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* If the return value of the notifier can be and'ed
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* with %NOTIFY_STOP_MASK then atomic_notifier_call_chain()
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* will return immediately, with the return value of
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* the notifier function which halted execution.
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* Otherwise the return value is the return value
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149 |
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* of the last notifier function called.
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*/
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151 |
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int __kprobes __atomic_notifier_call_chain(struct atomic_notifier_head *nh,
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152 |
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unsigned long val, void *v,
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int nr_to_call, int *nr_calls)
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154 |
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{
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155 |
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int ret;
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156 |
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rcu_read_lock();
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158 |
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ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
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rcu_read_unlock();
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return ret;
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}
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EXPORT_SYMBOL_GPL(__atomic_notifier_call_chain);
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int __kprobes atomic_notifier_call_chain(struct atomic_notifier_head *nh,
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unsigned long val, void *v)
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{
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return __atomic_notifier_call_chain(nh, val, v, -1, NULL);
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}
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EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);
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/*
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* Blocking notifier chain routines. All access to the chain is
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* synchronized by an rwsem.
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*/
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/**
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* blocking_notifier_chain_register - Add notifier to a blocking notifier chain
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* @nh: Pointer to head of the blocking notifier chain
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* @n: New entry in notifier chain
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*
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* Adds a notifier to a blocking notifier chain.
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* Must be called in process context.
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*
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* Currently always returns zero.
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*/
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int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
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struct notifier_block *n)
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{
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int ret;
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190 |
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/*
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192 |
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* This code gets used during boot-up, when task switching is
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* not yet working and interrupts must remain disabled. At
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194 |
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* such times we must not call down_write().
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195 |
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*/
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196 |
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if (unlikely(system_state == SYSTEM_BOOTING))
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return notifier_chain_register(&nh->head, n);
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199 |
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down_write(&nh->rwsem);
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ret = notifier_chain_register(&nh->head, n);
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up_write(&nh->rwsem);
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return ret;
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}
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204 |
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EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);
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205 |
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206 |
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/**
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207 |
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* blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain
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208 |
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* @nh: Pointer to head of the blocking notifier chain
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209 |
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* @n: Entry to remove from notifier chain
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210 |
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*
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211 |
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* Removes a notifier from a blocking notifier chain.
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212 |
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* Must be called from process context.
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213 |
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*
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214 |
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* Returns zero on success or %-ENOENT on failure.
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215 |
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*/
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216 |
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int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
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217 |
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struct notifier_block *n)
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218 |
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{
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219 |
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int ret;
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220 |
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221 |
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/*
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222 |
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* This code gets used during boot-up, when task switching is
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223 |
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* not yet working and interrupts must remain disabled. At
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224 |
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* such times we must not call down_write().
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225 |
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*/
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226 |
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if (unlikely(system_state == SYSTEM_BOOTING))
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227 |
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return notifier_chain_unregister(&nh->head, n);
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228 |
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229 |
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down_write(&nh->rwsem);
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230 |
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ret = notifier_chain_unregister(&nh->head, n);
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231 |
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up_write(&nh->rwsem);
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232 |
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return ret;
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233 |
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}
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234 |
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EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);
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235 |
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236 |
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/**
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237 |
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* __blocking_notifier_call_chain - Call functions in a blocking notifier chain
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238 |
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* @nh: Pointer to head of the blocking notifier chain
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239 |
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* @val: Value passed unmodified to notifier function
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240 |
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* @v: Pointer passed unmodified to notifier function
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241 |
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* @nr_to_call: See comment for notifier_call_chain.
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242 |
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* @nr_calls: See comment for notifier_call_chain.
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243 |
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*
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244 |
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* Calls each function in a notifier chain in turn. The functions
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245 |
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* run in a process context, so they are allowed to block.
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246 |
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*
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247 |
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* If the return value of the notifier can be and'ed
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248 |
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* with %NOTIFY_STOP_MASK then blocking_notifier_call_chain()
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249 |
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* will return immediately, with the return value of
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250 |
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* the notifier function which halted execution.
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251 |
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* Otherwise the return value is the return value
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252 |
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* of the last notifier function called.
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253 |
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*/
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254 |
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int __blocking_notifier_call_chain(struct blocking_notifier_head *nh,
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255 |
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unsigned long val, void *v,
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256 |
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int nr_to_call, int *nr_calls)
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257 |
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{
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258 |
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int ret = NOTIFY_DONE;
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259 |
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|
260 |
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/*
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261 |
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* We check the head outside the lock, but if this access is
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262 |
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* racy then it does not matter what the result of the test
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263 |
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* is, we re-check the list after having taken the lock anyway:
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264 |
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*/
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265 |
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if (rcu_dereference(nh->head)) {
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266 |
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down_read(&nh->rwsem);
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267 |
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ret = notifier_call_chain(&nh->head, val, v, nr_to_call,
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268 |
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nr_calls);
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269 |
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up_read(&nh->rwsem);
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270 |
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}
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271 |
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return ret;
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272 |
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}
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273 |
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EXPORT_SYMBOL_GPL(__blocking_notifier_call_chain);
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274 |
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|
275 |
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int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
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276 |
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unsigned long val, void *v)
|
277 |
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{
|
278 |
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return __blocking_notifier_call_chain(nh, val, v, -1, NULL);
|
279 |
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}
|
280 |
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EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);
|
281 |
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|
282 |
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/*
|
283 |
|
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* Raw notifier chain routines. There is no protection;
|
284 |
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* the caller must provide it. Use at your own risk!
|
285 |
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*/
|
286 |
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|
287 |
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/**
|
288 |
|
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* raw_notifier_chain_register - Add notifier to a raw notifier chain
|
289 |
|
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* @nh: Pointer to head of the raw notifier chain
|
290 |
|
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* @n: New entry in notifier chain
|
291 |
|
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*
|
292 |
|
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* Adds a notifier to a raw notifier chain.
|
293 |
|
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* All locking must be provided by the caller.
|
294 |
|
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*
|
295 |
|
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* Currently always returns zero.
|
296 |
|
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*/
|
297 |
|
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int raw_notifier_chain_register(struct raw_notifier_head *nh,
|
298 |
|
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struct notifier_block *n)
|
299 |
|
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{
|
300 |
|
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return notifier_chain_register(&nh->head, n);
|
301 |
|
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}
|
302 |
|
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EXPORT_SYMBOL_GPL(raw_notifier_chain_register);
|
303 |
|
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|
304 |
|
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/**
|
305 |
|
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* raw_notifier_chain_unregister - Remove notifier from a raw notifier chain
|
306 |
|
|
* @nh: Pointer to head of the raw notifier chain
|
307 |
|
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* @n: Entry to remove from notifier chain
|
308 |
|
|
*
|
309 |
|
|
* Removes a notifier from a raw notifier chain.
|
310 |
|
|
* All locking must be provided by the caller.
|
311 |
|
|
*
|
312 |
|
|
* Returns zero on success or %-ENOENT on failure.
|
313 |
|
|
*/
|
314 |
|
|
int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
|
315 |
|
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struct notifier_block *n)
|
316 |
|
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{
|
317 |
|
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return notifier_chain_unregister(&nh->head, n);
|
318 |
|
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}
|
319 |
|
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EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);
|
320 |
|
|
|
321 |
|
|
/**
|
322 |
|
|
* __raw_notifier_call_chain - Call functions in a raw notifier chain
|
323 |
|
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* @nh: Pointer to head of the raw notifier chain
|
324 |
|
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* @val: Value passed unmodified to notifier function
|
325 |
|
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* @v: Pointer passed unmodified to notifier function
|
326 |
|
|
* @nr_to_call: See comment for notifier_call_chain.
|
327 |
|
|
* @nr_calls: See comment for notifier_call_chain
|
328 |
|
|
*
|
329 |
|
|
* Calls each function in a notifier chain in turn. The functions
|
330 |
|
|
* run in an undefined context.
|
331 |
|
|
* All locking must be provided by the caller.
|
332 |
|
|
*
|
333 |
|
|
* If the return value of the notifier can be and'ed
|
334 |
|
|
* with %NOTIFY_STOP_MASK then raw_notifier_call_chain()
|
335 |
|
|
* will return immediately, with the return value of
|
336 |
|
|
* the notifier function which halted execution.
|
337 |
|
|
* Otherwise the return value is the return value
|
338 |
|
|
* of the last notifier function called.
|
339 |
|
|
*/
|
340 |
|
|
int __raw_notifier_call_chain(struct raw_notifier_head *nh,
|
341 |
|
|
unsigned long val, void *v,
|
342 |
|
|
int nr_to_call, int *nr_calls)
|
343 |
|
|
{
|
344 |
|
|
return notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
|
345 |
|
|
}
|
346 |
|
|
EXPORT_SYMBOL_GPL(__raw_notifier_call_chain);
|
347 |
|
|
|
348 |
|
|
int raw_notifier_call_chain(struct raw_notifier_head *nh,
|
349 |
|
|
unsigned long val, void *v)
|
350 |
|
|
{
|
351 |
|
|
return __raw_notifier_call_chain(nh, val, v, -1, NULL);
|
352 |
|
|
}
|
353 |
|
|
EXPORT_SYMBOL_GPL(raw_notifier_call_chain);
|
354 |
|
|
|
355 |
|
|
/*
|
356 |
|
|
* SRCU notifier chain routines. Registration and unregistration
|
357 |
|
|
* use a mutex, and call_chain is synchronized by SRCU (no locks).
|
358 |
|
|
*/
|
359 |
|
|
|
360 |
|
|
/**
|
361 |
|
|
* srcu_notifier_chain_register - Add notifier to an SRCU notifier chain
|
362 |
|
|
* @nh: Pointer to head of the SRCU notifier chain
|
363 |
|
|
* @n: New entry in notifier chain
|
364 |
|
|
*
|
365 |
|
|
* Adds a notifier to an SRCU notifier chain.
|
366 |
|
|
* Must be called in process context.
|
367 |
|
|
*
|
368 |
|
|
* Currently always returns zero.
|
369 |
|
|
*/
|
370 |
|
|
int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
|
371 |
|
|
struct notifier_block *n)
|
372 |
|
|
{
|
373 |
|
|
int ret;
|
374 |
|
|
|
375 |
|
|
/*
|
376 |
|
|
* This code gets used during boot-up, when task switching is
|
377 |
|
|
* not yet working and interrupts must remain disabled. At
|
378 |
|
|
* such times we must not call mutex_lock().
|
379 |
|
|
*/
|
380 |
|
|
if (unlikely(system_state == SYSTEM_BOOTING))
|
381 |
|
|
return notifier_chain_register(&nh->head, n);
|
382 |
|
|
|
383 |
|
|
mutex_lock(&nh->mutex);
|
384 |
|
|
ret = notifier_chain_register(&nh->head, n);
|
385 |
|
|
mutex_unlock(&nh->mutex);
|
386 |
|
|
return ret;
|
387 |
|
|
}
|
388 |
|
|
EXPORT_SYMBOL_GPL(srcu_notifier_chain_register);
|
389 |
|
|
|
390 |
|
|
/**
|
391 |
|
|
* srcu_notifier_chain_unregister - Remove notifier from an SRCU notifier chain
|
392 |
|
|
* @nh: Pointer to head of the SRCU notifier chain
|
393 |
|
|
* @n: Entry to remove from notifier chain
|
394 |
|
|
*
|
395 |
|
|
* Removes a notifier from an SRCU notifier chain.
|
396 |
|
|
* Must be called from process context.
|
397 |
|
|
*
|
398 |
|
|
* Returns zero on success or %-ENOENT on failure.
|
399 |
|
|
*/
|
400 |
|
|
int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
|
401 |
|
|
struct notifier_block *n)
|
402 |
|
|
{
|
403 |
|
|
int ret;
|
404 |
|
|
|
405 |
|
|
/*
|
406 |
|
|
* This code gets used during boot-up, when task switching is
|
407 |
|
|
* not yet working and interrupts must remain disabled. At
|
408 |
|
|
* such times we must not call mutex_lock().
|
409 |
|
|
*/
|
410 |
|
|
if (unlikely(system_state == SYSTEM_BOOTING))
|
411 |
|
|
return notifier_chain_unregister(&nh->head, n);
|
412 |
|
|
|
413 |
|
|
mutex_lock(&nh->mutex);
|
414 |
|
|
ret = notifier_chain_unregister(&nh->head, n);
|
415 |
|
|
mutex_unlock(&nh->mutex);
|
416 |
|
|
synchronize_srcu(&nh->srcu);
|
417 |
|
|
return ret;
|
418 |
|
|
}
|
419 |
|
|
EXPORT_SYMBOL_GPL(srcu_notifier_chain_unregister);
|
420 |
|
|
|
421 |
|
|
/**
|
422 |
|
|
* __srcu_notifier_call_chain - Call functions in an SRCU notifier chain
|
423 |
|
|
* @nh: Pointer to head of the SRCU notifier chain
|
424 |
|
|
* @val: Value passed unmodified to notifier function
|
425 |
|
|
* @v: Pointer passed unmodified to notifier function
|
426 |
|
|
* @nr_to_call: See comment for notifier_call_chain.
|
427 |
|
|
* @nr_calls: See comment for notifier_call_chain
|
428 |
|
|
*
|
429 |
|
|
* Calls each function in a notifier chain in turn. The functions
|
430 |
|
|
* run in a process context, so they are allowed to block.
|
431 |
|
|
*
|
432 |
|
|
* If the return value of the notifier can be and'ed
|
433 |
|
|
* with %NOTIFY_STOP_MASK then srcu_notifier_call_chain()
|
434 |
|
|
* will return immediately, with the return value of
|
435 |
|
|
* the notifier function which halted execution.
|
436 |
|
|
* Otherwise the return value is the return value
|
437 |
|
|
* of the last notifier function called.
|
438 |
|
|
*/
|
439 |
|
|
int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
|
440 |
|
|
unsigned long val, void *v,
|
441 |
|
|
int nr_to_call, int *nr_calls)
|
442 |
|
|
{
|
443 |
|
|
int ret;
|
444 |
|
|
int idx;
|
445 |
|
|
|
446 |
|
|
idx = srcu_read_lock(&nh->srcu);
|
447 |
|
|
ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
|
448 |
|
|
srcu_read_unlock(&nh->srcu, idx);
|
449 |
|
|
return ret;
|
450 |
|
|
}
|
451 |
|
|
EXPORT_SYMBOL_GPL(__srcu_notifier_call_chain);
|
452 |
|
|
|
453 |
|
|
int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
|
454 |
|
|
unsigned long val, void *v)
|
455 |
|
|
{
|
456 |
|
|
return __srcu_notifier_call_chain(nh, val, v, -1, NULL);
|
457 |
|
|
}
|
458 |
|
|
EXPORT_SYMBOL_GPL(srcu_notifier_call_chain);
|
459 |
|
|
|
460 |
|
|
/**
|
461 |
|
|
* srcu_init_notifier_head - Initialize an SRCU notifier head
|
462 |
|
|
* @nh: Pointer to head of the srcu notifier chain
|
463 |
|
|
*
|
464 |
|
|
* Unlike other sorts of notifier heads, SRCU notifier heads require
|
465 |
|
|
* dynamic initialization. Be sure to call this routine before
|
466 |
|
|
* calling any of the other SRCU notifier routines for this head.
|
467 |
|
|
*
|
468 |
|
|
* If an SRCU notifier head is deallocated, it must first be cleaned
|
469 |
|
|
* up by calling srcu_cleanup_notifier_head(). Otherwise the head's
|
470 |
|
|
* per-cpu data (used by the SRCU mechanism) will leak.
|
471 |
|
|
*/
|
472 |
|
|
void srcu_init_notifier_head(struct srcu_notifier_head *nh)
|
473 |
|
|
{
|
474 |
|
|
mutex_init(&nh->mutex);
|
475 |
|
|
if (init_srcu_struct(&nh->srcu) < 0)
|
476 |
|
|
BUG();
|
477 |
|
|
nh->head = NULL;
|
478 |
|
|
}
|
479 |
|
|
EXPORT_SYMBOL_GPL(srcu_init_notifier_head);
|
480 |
|
|
|
481 |
|
|
/**
|
482 |
|
|
* register_reboot_notifier - Register function to be called at reboot time
|
483 |
|
|
* @nb: Info about notifier function to be called
|
484 |
|
|
*
|
485 |
|
|
* Registers a function with the list of functions
|
486 |
|
|
* to be called at reboot time.
|
487 |
|
|
*
|
488 |
|
|
* Currently always returns zero, as blocking_notifier_chain_register()
|
489 |
|
|
* always returns zero.
|
490 |
|
|
*/
|
491 |
|
|
int register_reboot_notifier(struct notifier_block *nb)
|
492 |
|
|
{
|
493 |
|
|
return blocking_notifier_chain_register(&reboot_notifier_list, nb);
|
494 |
|
|
}
|
495 |
|
|
EXPORT_SYMBOL(register_reboot_notifier);
|
496 |
|
|
|
497 |
|
|
/**
|
498 |
|
|
* unregister_reboot_notifier - Unregister previously registered reboot notifier
|
499 |
|
|
* @nb: Hook to be unregistered
|
500 |
|
|
*
|
501 |
|
|
* Unregisters a previously registered reboot
|
502 |
|
|
* notifier function.
|
503 |
|
|
*
|
504 |
|
|
* Returns zero on success, or %-ENOENT on failure.
|
505 |
|
|
*/
|
506 |
|
|
int unregister_reboot_notifier(struct notifier_block *nb)
|
507 |
|
|
{
|
508 |
|
|
return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
|
509 |
|
|
}
|
510 |
|
|
EXPORT_SYMBOL(unregister_reboot_notifier);
|
511 |
|
|
|
512 |
|
|
static ATOMIC_NOTIFIER_HEAD(die_chain);
|
513 |
|
|
|
514 |
|
|
int notify_die(enum die_val val, const char *str,
|
515 |
|
|
struct pt_regs *regs, long err, int trap, int sig)
|
516 |
|
|
{
|
517 |
|
|
struct die_args args = {
|
518 |
|
|
.regs = regs,
|
519 |
|
|
.str = str,
|
520 |
|
|
.err = err,
|
521 |
|
|
.trapnr = trap,
|
522 |
|
|
.signr = sig,
|
523 |
|
|
|
524 |
|
|
};
|
525 |
|
|
return atomic_notifier_call_chain(&die_chain, val, &args);
|
526 |
|
|
}
|
527 |
|
|
|
528 |
|
|
int register_die_notifier(struct notifier_block *nb)
|
529 |
|
|
{
|
530 |
|
|
vmalloc_sync_all();
|
531 |
|
|
return atomic_notifier_chain_register(&die_chain, nb);
|
532 |
|
|
}
|
533 |
|
|
EXPORT_SYMBOL_GPL(register_die_notifier);
|
534 |
|
|
|
535 |
|
|
int unregister_die_notifier(struct notifier_block *nb)
|
536 |
|
|
{
|
537 |
|
|
return atomic_notifier_chain_unregister(&die_chain, nb);
|
538 |
|
|
}
|
539 |
|
|
EXPORT_SYMBOL_GPL(unregister_die_notifier);
|