567 lines
16 KiB
C
567 lines
16 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/kdebug.h>
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#include <linux/kprobes.h>
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#include <linux/export.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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#include <linux/reboot.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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WARN_ONCE(((*nl) == n), "double register detected");
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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_cond_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 ((*nl) == n)
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return 0;
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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 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_raw(*nl);
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while (nb && nr_to_call) {
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next_nb = rcu_dereference_raw(nb->next);
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#ifdef CONFIG_DEBUG_NOTIFIERS
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if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) {
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WARN(1, "Invalid notifier called!");
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nb = next_nb;
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continue;
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}
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#endif
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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)
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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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NOKPROBE_SYMBOL(notifier_call_chain);
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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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* 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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* of the last notifier function called.
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*/
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int __atomic_notifier_call_chain(struct atomic_notifier_head *nh,
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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;
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rcu_read_lock();
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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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NOKPROBE_SYMBOL(__atomic_notifier_call_chain);
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int 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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NOKPROBE_SYMBOL(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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/*
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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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* such times we must not call down_write().
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*/
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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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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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EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);
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/**
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* blocking_notifier_chain_cond_register - Cond 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, only if not already
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* present in the 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_cond_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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down_write(&nh->rwsem);
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ret = notifier_chain_cond_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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EXPORT_SYMBOL_GPL(blocking_notifier_chain_cond_register);
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/**
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* blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain
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* @nh: Pointer to head of the blocking 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 a blocking notifier chain.
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* Must be called from process context.
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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 blocking_notifier_chain_unregister(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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/*
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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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* such times we must not call down_write().
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*/
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if (unlikely(system_state == SYSTEM_BOOTING))
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return notifier_chain_unregister(&nh->head, n);
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down_write(&nh->rwsem);
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ret = notifier_chain_unregister(&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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EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);
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/**
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* __blocking_notifier_call_chain - Call functions in a blocking notifier chain
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* @nh: 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: See comment for notifier_call_chain.
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* @nr_calls: See comment for notifier_call_chain.
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*
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* Calls each function in a notifier chain in turn. The functions
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* run in a process context, so they are allowed to block.
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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 blocking_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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* of the last notifier function called.
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*/
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int __blocking_notifier_call_chain(struct blocking_notifier_head *nh,
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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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/*
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* We check the head outside the lock, but if this access is
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* racy then it does not matter what the result of the test
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* is, we re-check the list after having taken the lock anyway:
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*/
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if (rcu_access_pointer(nh->head)) {
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down_read(&nh->rwsem);
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ret = notifier_call_chain(&nh->head, val, v, nr_to_call,
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nr_calls);
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up_read(&nh->rwsem);
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(__blocking_notifier_call_chain);
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int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
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unsigned long val, void *v)
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{
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return __blocking_notifier_call_chain(nh, val, v, -1, NULL);
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}
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EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);
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/*
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* Raw notifier chain routines. There is no protection;
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* the caller must provide it. Use at your own risk!
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*/
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/**
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* raw_notifier_chain_register - Add notifier to a raw notifier chain
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* @nh: Pointer to head of the raw 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 raw notifier chain.
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* All locking must be provided by the caller.
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*
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* Currently always returns zero.
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*/
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int raw_notifier_chain_register(struct raw_notifier_head *nh,
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struct notifier_block *n)
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{
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return notifier_chain_register(&nh->head, n);
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}
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EXPORT_SYMBOL_GPL(raw_notifier_chain_register);
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/**
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* raw_notifier_chain_unregister - Remove notifier from a raw notifier chain
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* @nh: Pointer to head of the raw 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 a raw notifier chain.
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* All locking must be provided by the caller.
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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 raw_notifier_chain_unregister(struct raw_notifier_head *nh,
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struct notifier_block *n)
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{
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return notifier_chain_unregister(&nh->head, n);
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}
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EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);
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/**
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* __raw_notifier_call_chain - Call functions in a raw notifier chain
|
||
|
|
* @nh: Pointer to head of the raw notifier chain
|
||
|
|
* @val: Value passed unmodified to notifier function
|
||
|
|
* @v: Pointer passed unmodified to notifier function
|
||
|
|
* @nr_to_call: See comment for notifier_call_chain.
|
||
|
|
* @nr_calls: See comment for notifier_call_chain
|
||
|
|
*
|
||
|
|
* Calls each function in a notifier chain in turn. The functions
|
||
|
|
* run in an undefined context.
|
||
|
|
* All locking must be provided by the caller.
|
||
|
|
*
|
||
|
|
* If the return value of the notifier can be and'ed
|
||
|
|
* with %NOTIFY_STOP_MASK then raw_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 __raw_notifier_call_chain(struct raw_notifier_head *nh,
|
||
|
|
unsigned long val, void *v,
|
||
|
|
int nr_to_call, int *nr_calls)
|
||
|
|
{
|
||
|
|
return notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(__raw_notifier_call_chain);
|
||
|
|
|
||
|
|
int raw_notifier_call_chain(struct raw_notifier_head *nh,
|
||
|
|
unsigned long val, void *v)
|
||
|
|
{
|
||
|
|
return __raw_notifier_call_chain(nh, val, v, -1, NULL);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(raw_notifier_call_chain);
|
||
|
|
|
||
|
|
#ifdef CONFIG_SRCU
|
||
|
|
/*
|
||
|
|
* SRCU notifier chain routines. Registration and unregistration
|
||
|
|
* use a mutex, and call_chain is synchronized by SRCU (no locks).
|
||
|
|
*/
|
||
|
|
|
||
|
|
/**
|
||
|
|
* srcu_notifier_chain_register - Add notifier to an SRCU notifier chain
|
||
|
|
* @nh: Pointer to head of the SRCU notifier chain
|
||
|
|
* @n: New entry in notifier chain
|
||
|
|
*
|
||
|
|
* Adds a notifier to an SRCU notifier chain.
|
||
|
|
* Must be called in process context.
|
||
|
|
*
|
||
|
|
* Currently always returns zero.
|
||
|
|
*/
|
||
|
|
int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
|
||
|
|
struct notifier_block *n)
|
||
|
|
{
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
/*
|
||
|
|
* This code gets used during boot-up, when task switching is
|
||
|
|
* not yet working and interrupts must remain disabled. At
|
||
|
|
* such times we must not call mutex_lock().
|
||
|
|
*/
|
||
|
|
if (unlikely(system_state == SYSTEM_BOOTING))
|
||
|
|
return notifier_chain_register(&nh->head, n);
|
||
|
|
|
||
|
|
mutex_lock(&nh->mutex);
|
||
|
|
ret = notifier_chain_register(&nh->head, n);
|
||
|
|
mutex_unlock(&nh->mutex);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(srcu_notifier_chain_register);
|
||
|
|
|
||
|
|
/**
|
||
|
|
* srcu_notifier_chain_unregister - Remove notifier from an SRCU notifier chain
|
||
|
|
* @nh: Pointer to head of the SRCU notifier chain
|
||
|
|
* @n: Entry to remove from notifier chain
|
||
|
|
*
|
||
|
|
* Removes a notifier from an SRCU notifier chain.
|
||
|
|
* Must be called from process context.
|
||
|
|
*
|
||
|
|
* Returns zero on success or %-ENOENT on failure.
|
||
|
|
*/
|
||
|
|
int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
|
||
|
|
struct notifier_block *n)
|
||
|
|
{
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
/*
|
||
|
|
* This code gets used during boot-up, when task switching is
|
||
|
|
* not yet working and interrupts must remain disabled. At
|
||
|
|
* such times we must not call mutex_lock().
|
||
|
|
*/
|
||
|
|
if (unlikely(system_state == SYSTEM_BOOTING))
|
||
|
|
return notifier_chain_unregister(&nh->head, n);
|
||
|
|
|
||
|
|
mutex_lock(&nh->mutex);
|
||
|
|
ret = notifier_chain_unregister(&nh->head, n);
|
||
|
|
mutex_unlock(&nh->mutex);
|
||
|
|
synchronize_srcu(&nh->srcu);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(srcu_notifier_chain_unregister);
|
||
|
|
|
||
|
|
/**
|
||
|
|
* __srcu_notifier_call_chain - Call functions in an SRCU notifier chain
|
||
|
|
* @nh: Pointer to head of the SRCU notifier chain
|
||
|
|
* @val: Value passed unmodified to notifier function
|
||
|
|
* @v: Pointer passed unmodified to notifier function
|
||
|
|
* @nr_to_call: See comment for notifier_call_chain.
|
||
|
|
* @nr_calls: See comment for notifier_call_chain
|
||
|
|
*
|
||
|
|
* Calls each function in a notifier chain in turn. The functions
|
||
|
|
* run in a process context, so they are allowed to block.
|
||
|
|
*
|
||
|
|
* If the return value of the notifier can be and'ed
|
||
|
|
* with %NOTIFY_STOP_MASK then srcu_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 __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
|
||
|
|
unsigned long val, void *v,
|
||
|
|
int nr_to_call, int *nr_calls)
|
||
|
|
{
|
||
|
|
int ret;
|
||
|
|
int idx;
|
||
|
|
|
||
|
|
idx = srcu_read_lock(&nh->srcu);
|
||
|
|
ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
|
||
|
|
srcu_read_unlock(&nh->srcu, idx);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(__srcu_notifier_call_chain);
|
||
|
|
|
||
|
|
int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
|
||
|
|
unsigned long val, void *v)
|
||
|
|
{
|
||
|
|
return __srcu_notifier_call_chain(nh, val, v, -1, NULL);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(srcu_notifier_call_chain);
|
||
|
|
|
||
|
|
/**
|
||
|
|
* srcu_init_notifier_head - Initialize an SRCU notifier head
|
||
|
|
* @nh: Pointer to head of the srcu notifier chain
|
||
|
|
*
|
||
|
|
* Unlike other sorts of notifier heads, SRCU notifier heads require
|
||
|
|
* dynamic initialization. Be sure to call this routine before
|
||
|
|
* calling any of the other SRCU notifier routines for this head.
|
||
|
|
*
|
||
|
|
* If an SRCU notifier head is deallocated, it must first be cleaned
|
||
|
|
* up by calling srcu_cleanup_notifier_head(). Otherwise the head's
|
||
|
|
* per-cpu data (used by the SRCU mechanism) will leak.
|
||
|
|
*/
|
||
|
|
void srcu_init_notifier_head(struct srcu_notifier_head *nh)
|
||
|
|
{
|
||
|
|
mutex_init(&nh->mutex);
|
||
|
|
if (init_srcu_struct(&nh->srcu) < 0)
|
||
|
|
BUG();
|
||
|
|
nh->head = NULL;
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(srcu_init_notifier_head);
|
||
|
|
|
||
|
|
#endif /* CONFIG_SRCU */
|
||
|
|
|
||
|
|
static ATOMIC_NOTIFIER_HEAD(die_chain);
|
||
|
|
|
||
|
|
int notrace notify_die(enum die_val val, const char *str,
|
||
|
|
struct pt_regs *regs, long err, int trap, int sig)
|
||
|
|
{
|
||
|
|
struct die_args args = {
|
||
|
|
.regs = regs,
|
||
|
|
.str = str,
|
||
|
|
.err = err,
|
||
|
|
.trapnr = trap,
|
||
|
|
.signr = sig,
|
||
|
|
|
||
|
|
};
|
||
|
|
RCU_LOCKDEP_WARN(!rcu_is_watching(),
|
||
|
|
"notify_die called but RCU thinks we're quiescent");
|
||
|
|
return atomic_notifier_call_chain(&die_chain, val, &args);
|
||
|
|
}
|
||
|
|
NOKPROBE_SYMBOL(notify_die);
|
||
|
|
|
||
|
|
int register_die_notifier(struct notifier_block *nb)
|
||
|
|
{
|
||
|
|
vmalloc_sync_mappings();
|
||
|
|
return atomic_notifier_chain_register(&die_chain, nb);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(register_die_notifier);
|
||
|
|
|
||
|
|
int unregister_die_notifier(struct notifier_block *nb)
|
||
|
|
{
|
||
|
|
return atomic_notifier_chain_unregister(&die_chain, nb);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(unregister_die_notifier);
|