[Devel] [PATCH] Add kernel/notifier.c
Alexey Dobriyan
adobriyan at sw.ru
Thu Jul 19 09:46:11 PDT 2007
There is separate notifier header, but no separate notifier .c file.
Extract notifier code out of kernel/sys.c which will remain for
misc syscalls I hope. Merge kernel/die_notifier.c into kernel/notifier.c.
Signed-off-by: Alexey Dobriyan <adobriyan at sw.ru>
---
include/linux/notifier.h | 2
kernel/Makefile | 4
kernel/die_notifier.c | 38 ---
kernel/notifier.c | 569 +++++++++++++++++++++++++++++++++++++++++++++++
kernel/sys.c | 531 -------------------------------------------
5 files changed, 573 insertions(+), 571 deletions(-)
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -212,5 +212,7 @@ extern int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
#define CPU_DEAD_FROZEN (CPU_DEAD | CPU_TASKS_FROZEN)
#define CPU_DYING_FROZEN (CPU_DYING | CPU_TASKS_FROZEN)
+extern struct blocking_notifier_head reboot_notifier_list;
+
#endif /* __KERNEL__ */
#endif /* _LINUX_NOTIFIER_H */
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -8,8 +8,8 @@ obj-y = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
signal.o sys.o kmod.o workqueue.o pid.o \
rcupdate.o extable.o params.o posix-timers.o \
kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
- hrtimer.o rwsem.o latency.o nsproxy.o srcu.o die_notifier.o \
- utsname.o
+ hrtimer.o rwsem.o latency.o nsproxy.o srcu.o \
+ utsname.o notifier.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-y += time/
deleted file mode 100644
--- a/kernel/die_notifier.c
+++ /dev/null
@@ -1,38 +0,0 @@
-
-#include <linux/module.h>
-#include <linux/notifier.h>
-#include <linux/vmalloc.h>
-#include <linux/kdebug.h>
-
-
-static ATOMIC_NOTIFIER_HEAD(die_chain);
-
-int 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,
-
- };
-
- return atomic_notifier_call_chain(&die_chain, val, &args);
-}
-
-int register_die_notifier(struct notifier_block *nb)
-{
- vmalloc_sync_all();
- 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);
-
-
--- /dev/null
+++ b/kernel/notifier.c
@@ -0,0 +1,569 @@
+#include <linux/kdebug.h>
+#include <linux/kprobes.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/rcupdate.h>
+#include <linux/vmalloc.h>
+
+/*
+ * Notifier list for kernel code which wants to be called
+ * at shutdown. This is used to stop any idling DMA operations
+ * and the like.
+ */
+
+BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);
+
+/*
+ * Notifier chain core routines. The exported routines below
+ * are layered on top of these, with appropriate locking added.
+ */
+
+static int notifier_chain_register(struct notifier_block **nl,
+ struct notifier_block *n)
+{
+ while ((*nl) != NULL) {
+ if (n->priority > (*nl)->priority)
+ break;
+ nl = &((*nl)->next);
+ }
+ n->next = *nl;
+ rcu_assign_pointer(*nl, n);
+ return 0;
+}
+
+static int notifier_chain_unregister(struct notifier_block **nl,
+ struct notifier_block *n)
+{
+ while ((*nl) != NULL) {
+ if ((*nl) == n) {
+ rcu_assign_pointer(*nl, n->next);
+ return 0;
+ }
+ nl = &((*nl)->next);
+ }
+ return -ENOENT;
+}
+
+/**
+ * notifier_call_chain - Informs the registered notifiers about an event.
+ * @nl: Pointer to head of the blocking notifier chain
+ * @val: Value passed unmodified to notifier function
+ * @v: Pointer passed unmodified to notifier function
+ * @nr_to_call: Number of notifier functions to be called. Don't care
+ * value of this parameter is -1.
+ * @nr_calls: Records the number of notifications sent. Don't care
+ * value of this field is NULL.
+ * @returns: notifier_call_chain returns the value returned by the
+ * last notifier function called.
+ */
+
+static int __kprobes notifier_call_chain(struct notifier_block **nl,
+ unsigned long val, void *v,
+ int nr_to_call, int *nr_calls)
+{
+ int ret = NOTIFY_DONE;
+ struct notifier_block *nb, *next_nb;
+
+ nb = rcu_dereference(*nl);
+
+ while (nb && nr_to_call) {
+ next_nb = rcu_dereference(nb->next);
+ ret = nb->notifier_call(nb, val, v);
+
+ if (nr_calls)
+ (*nr_calls)++;
+
+ if ((ret & NOTIFY_STOP_MASK) == NOTIFY_STOP_MASK)
+ break;
+ nb = next_nb;
+ nr_to_call--;
+ }
+ return ret;
+}
+
+/*
+ * Atomic notifier chain routines. Registration and unregistration
+ * use a spinlock, and call_chain is synchronized by RCU (no locks).
+ */
+
+/**
+ * atomic_notifier_chain_register - Add notifier to an atomic notifier chain
+ * @nh: Pointer to head of the atomic notifier chain
+ * @n: New entry in notifier chain
+ *
+ * Adds a notifier to an atomic notifier chain.
+ *
+ * Currently always returns zero.
+ */
+
+int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
+ struct notifier_block *n)
+{
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&nh->lock, flags);
+ ret = notifier_chain_register(&nh->head, n);
+ spin_unlock_irqrestore(&nh->lock, flags);
+ return ret;
+}
+
+EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);
+
+/**
+ * atomic_notifier_chain_unregister - Remove notifier from an atomic notifier chain
+ * @nh: Pointer to head of the atomic notifier chain
+ * @n: Entry to remove from notifier chain
+ *
+ * Removes a notifier from an atomic notifier chain.
+ *
+ * Returns zero on success or %-ENOENT on failure.
+ */
+int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
+ struct notifier_block *n)
+{
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&nh->lock, flags);
+ ret = notifier_chain_unregister(&nh->head, n);
+ spin_unlock_irqrestore(&nh->lock, flags);
+ synchronize_rcu();
+ return ret;
+}
+
+EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);
+
+/**
+ * __atomic_notifier_call_chain - Call functions in an atomic notifier chain
+ * @nh: Pointer to head of the atomic 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 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 __atomic_notifier_call_chain(struct 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(__atomic_notifier_call_chain);
+
+int __kprobes atomic_notifier_call_chain(struct atomic_notifier_head *nh,
+ unsigned long val, void *v)
+{
+ return __atomic_notifier_call_chain(nh, val, v, -1, NULL);
+}
+
+EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);
+/*
+ * Blocking notifier chain routines. All access to the chain is
+ * synchronized by an rwsem.
+ */
+
+/**
+ * blocking_notifier_chain_register - Add notifier to a blocking notifier chain
+ * @nh: Pointer to head of the blocking notifier chain
+ * @n: New entry in notifier chain
+ *
+ * Adds a notifier to a blocking notifier chain.
+ * Must be called in process context.
+ *
+ * Currently always returns zero.
+ */
+
+int blocking_notifier_chain_register(struct blocking_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 down_write().
+ */
+ if (unlikely(system_state == SYSTEM_BOOTING))
+ return notifier_chain_register(&nh->head, n);
+
+ down_write(&nh->rwsem);
+ ret = notifier_chain_register(&nh->head, n);
+ up_write(&nh->rwsem);
+ return ret;
+}
+
+EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);
+
+/**
+ * blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain
+ * @nh: Pointer to head of the blocking notifier chain
+ * @n: Entry to remove from notifier chain
+ *
+ * Removes a notifier from a blocking notifier chain.
+ * Must be called from process context.
+ *
+ * Returns zero on success or %-ENOENT on failure.
+ */
+int blocking_notifier_chain_unregister(struct blocking_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 down_write().
+ */
+ if (unlikely(system_state == SYSTEM_BOOTING))
+ return notifier_chain_unregister(&nh->head, n);
+
+ down_write(&nh->rwsem);
+ ret = notifier_chain_unregister(&nh->head, n);
+ up_write(&nh->rwsem);
+ return ret;
+}
+
+EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);
+
+/**
+ * __blocking_notifier_call_chain - Call functions in a blocking notifier chain
+ * @nh: Pointer to head of the blocking 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 blocking_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 __blocking_notifier_call_chain(struct blocking_notifier_head *nh,
+ unsigned long val, void *v,
+ int nr_to_call, int *nr_calls)
+{
+ int ret = NOTIFY_DONE;
+
+ /*
+ * We check the head outside the lock, but if this access is
+ * racy then it does not matter what the result of the test
+ * is, we re-check the list after having taken the lock anyway:
+ */
+ if (rcu_dereference(nh->head)) {
+ down_read(&nh->rwsem);
+ ret = notifier_call_chain(&nh->head, val, v, nr_to_call,
+ nr_calls);
+ up_read(&nh->rwsem);
+ }
+ return ret;
+}
+EXPORT_SYMBOL_GPL(__blocking_notifier_call_chain);
+
+int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
+ unsigned long val, void *v)
+{
+ return __blocking_notifier_call_chain(nh, val, v, -1, NULL);
+}
+EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);
+
+/*
+ * Raw notifier chain routines. There is no protection;
+ * the caller must provide it. Use at your own risk!
+ */
+
+/**
+ * raw_notifier_chain_register - Add notifier to a raw notifier chain
+ * @nh: Pointer to head of the raw notifier chain
+ * @n: New entry in notifier chain
+ *
+ * Adds a notifier to a raw notifier chain.
+ * All locking must be provided by the caller.
+ *
+ * Currently always returns zero.
+ */
+
+int raw_notifier_chain_register(struct raw_notifier_head *nh,
+ struct notifier_block *n)
+{
+ return notifier_chain_register(&nh->head, n);
+}
+
+EXPORT_SYMBOL_GPL(raw_notifier_chain_register);
+
+/**
+ * raw_notifier_chain_unregister - Remove notifier from a raw notifier chain
+ * @nh: Pointer to head of the raw notifier chain
+ * @n: Entry to remove from notifier chain
+ *
+ * Removes a notifier from a raw notifier chain.
+ * All locking must be provided by the caller.
+ *
+ * Returns zero on success or %-ENOENT on failure.
+ */
+int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
+ struct notifier_block *n)
+{
+ return notifier_chain_unregister(&nh->head, n);
+}
+
+EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);
+
+/**
+ * __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);
+
+/*
+ * 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);
+
+/**
+ * register_reboot_notifier - Register function to be called at reboot time
+ * @nb: Info about notifier function to be called
+ *
+ * Registers a function with the list of functions
+ * to be called at reboot time.
+ *
+ * Currently always returns zero, as blocking_notifier_chain_register()
+ * always returns zero.
+ */
+
+int register_reboot_notifier(struct notifier_block * nb)
+{
+ return blocking_notifier_chain_register(&reboot_notifier_list, nb);
+}
+
+EXPORT_SYMBOL(register_reboot_notifier);
+
+/**
+ * unregister_reboot_notifier - Unregister previously registered reboot notifier
+ * @nb: Hook to be unregistered
+ *
+ * Unregisters a previously registered reboot
+ * notifier function.
+ *
+ * Returns zero on success, or %-ENOENT on failure.
+ */
+
+int unregister_reboot_notifier(struct notifier_block * nb)
+{
+ return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
+}
+
+EXPORT_SYMBOL(unregister_reboot_notifier);
+
+
+
+static ATOMIC_NOTIFIER_HEAD(die_chain);
+
+int 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,
+
+ };
+
+ return atomic_notifier_call_chain(&die_chain, val, &args);
+}
+
+int register_die_notifier(struct notifier_block *nb)
+{
+ vmalloc_sync_all();
+ 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);
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -99,537 +99,6 @@ int C_A_D = 1;
struct pid *cad_pid;
EXPORT_SYMBOL(cad_pid);
-/*
- * Notifier list for kernel code which wants to be called
- * at shutdown. This is used to stop any idling DMA operations
- * and the like.
- */
-
-static BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);
-
-/*
- * Notifier chain core routines. The exported routines below
- * are layered on top of these, with appropriate locking added.
- */
-
-static int notifier_chain_register(struct notifier_block **nl,
- struct notifier_block *n)
-{
- while ((*nl) != NULL) {
- if (n->priority > (*nl)->priority)
- break;
- nl = &((*nl)->next);
- }
- n->next = *nl;
- rcu_assign_pointer(*nl, n);
- return 0;
-}
-
-static int notifier_chain_unregister(struct notifier_block **nl,
- struct notifier_block *n)
-{
- while ((*nl) != NULL) {
- if ((*nl) == n) {
- rcu_assign_pointer(*nl, n->next);
- return 0;
- }
- nl = &((*nl)->next);
- }
- return -ENOENT;
-}
-
-/**
- * notifier_call_chain - Informs the registered notifiers about an event.
- * @nl: Pointer to head of the blocking notifier chain
- * @val: Value passed unmodified to notifier function
- * @v: Pointer passed unmodified to notifier function
- * @nr_to_call: Number of notifier functions to be called. Don't care
- * value of this parameter is -1.
- * @nr_calls: Records the number of notifications sent. Don't care
- * value of this field is NULL.
- * @returns: notifier_call_chain returns the value returned by the
- * last notifier function called.
- */
-
-static int __kprobes notifier_call_chain(struct notifier_block **nl,
- unsigned long val, void *v,
- int nr_to_call, int *nr_calls)
-{
- int ret = NOTIFY_DONE;
- struct notifier_block *nb, *next_nb;
-
- nb = rcu_dereference(*nl);
-
- while (nb && nr_to_call) {
- next_nb = rcu_dereference(nb->next);
- ret = nb->notifier_call(nb, val, v);
-
- if (nr_calls)
- (*nr_calls)++;
-
- if ((ret & NOTIFY_STOP_MASK) == NOTIFY_STOP_MASK)
- break;
- nb = next_nb;
- nr_to_call--;
- }
- return ret;
-}
-
-/*
- * Atomic notifier chain routines. Registration and unregistration
- * use a spinlock, and call_chain is synchronized by RCU (no locks).
- */
-
-/**
- * atomic_notifier_chain_register - Add notifier to an atomic notifier chain
- * @nh: Pointer to head of the atomic notifier chain
- * @n: New entry in notifier chain
- *
- * Adds a notifier to an atomic notifier chain.
- *
- * Currently always returns zero.
- */
-
-int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
- struct notifier_block *n)
-{
- unsigned long flags;
- int ret;
-
- spin_lock_irqsave(&nh->lock, flags);
- ret = notifier_chain_register(&nh->head, n);
- spin_unlock_irqrestore(&nh->lock, flags);
- return ret;
-}
-
-EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);
-
-/**
- * atomic_notifier_chain_unregister - Remove notifier from an atomic notifier chain
- * @nh: Pointer to head of the atomic notifier chain
- * @n: Entry to remove from notifier chain
- *
- * Removes a notifier from an atomic notifier chain.
- *
- * Returns zero on success or %-ENOENT on failure.
- */
-int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
- struct notifier_block *n)
-{
- unsigned long flags;
- int ret;
-
- spin_lock_irqsave(&nh->lock, flags);
- ret = notifier_chain_unregister(&nh->head, n);
- spin_unlock_irqrestore(&nh->lock, flags);
- synchronize_rcu();
- return ret;
-}
-
-EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);
-
-/**
- * __atomic_notifier_call_chain - Call functions in an atomic notifier chain
- * @nh: Pointer to head of the atomic 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 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 __atomic_notifier_call_chain(struct 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(__atomic_notifier_call_chain);
-
-int __kprobes atomic_notifier_call_chain(struct atomic_notifier_head *nh,
- unsigned long val, void *v)
-{
- return __atomic_notifier_call_chain(nh, val, v, -1, NULL);
-}
-
-EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);
-/*
- * Blocking notifier chain routines. All access to the chain is
- * synchronized by an rwsem.
- */
-
-/**
- * blocking_notifier_chain_register - Add notifier to a blocking notifier chain
- * @nh: Pointer to head of the blocking notifier chain
- * @n: New entry in notifier chain
- *
- * Adds a notifier to a blocking notifier chain.
- * Must be called in process context.
- *
- * Currently always returns zero.
- */
-
-int blocking_notifier_chain_register(struct blocking_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 down_write().
- */
- if (unlikely(system_state == SYSTEM_BOOTING))
- return notifier_chain_register(&nh->head, n);
-
- down_write(&nh->rwsem);
- ret = notifier_chain_register(&nh->head, n);
- up_write(&nh->rwsem);
- return ret;
-}
-
-EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);
-
-/**
- * blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain
- * @nh: Pointer to head of the blocking notifier chain
- * @n: Entry to remove from notifier chain
- *
- * Removes a notifier from a blocking notifier chain.
- * Must be called from process context.
- *
- * Returns zero on success or %-ENOENT on failure.
- */
-int blocking_notifier_chain_unregister(struct blocking_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 down_write().
- */
- if (unlikely(system_state == SYSTEM_BOOTING))
- return notifier_chain_unregister(&nh->head, n);
-
- down_write(&nh->rwsem);
- ret = notifier_chain_unregister(&nh->head, n);
- up_write(&nh->rwsem);
- return ret;
-}
-
-EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);
-
-/**
- * __blocking_notifier_call_chain - Call functions in a blocking notifier chain
- * @nh: Pointer to head of the blocking 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 blocking_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 __blocking_notifier_call_chain(struct blocking_notifier_head *nh,
- unsigned long val, void *v,
- int nr_to_call, int *nr_calls)
-{
- int ret = NOTIFY_DONE;
-
- /*
- * We check the head outside the lock, but if this access is
- * racy then it does not matter what the result of the test
- * is, we re-check the list after having taken the lock anyway:
- */
- if (rcu_dereference(nh->head)) {
- down_read(&nh->rwsem);
- ret = notifier_call_chain(&nh->head, val, v, nr_to_call,
- nr_calls);
- up_read(&nh->rwsem);
- }
- return ret;
-}
-EXPORT_SYMBOL_GPL(__blocking_notifier_call_chain);
-
-int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
- unsigned long val, void *v)
-{
- return __blocking_notifier_call_chain(nh, val, v, -1, NULL);
-}
-EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);
-
-/*
- * Raw notifier chain routines. There is no protection;
- * the caller must provide it. Use at your own risk!
- */
-
-/**
- * raw_notifier_chain_register - Add notifier to a raw notifier chain
- * @nh: Pointer to head of the raw notifier chain
- * @n: New entry in notifier chain
- *
- * Adds a notifier to a raw notifier chain.
- * All locking must be provided by the caller.
- *
- * Currently always returns zero.
- */
-
-int raw_notifier_chain_register(struct raw_notifier_head *nh,
- struct notifier_block *n)
-{
- return notifier_chain_register(&nh->head, n);
-}
-
-EXPORT_SYMBOL_GPL(raw_notifier_chain_register);
-
-/**
- * raw_notifier_chain_unregister - Remove notifier from a raw notifier chain
- * @nh: Pointer to head of the raw notifier chain
- * @n: Entry to remove from notifier chain
- *
- * Removes a notifier from a raw notifier chain.
- * All locking must be provided by the caller.
- *
- * Returns zero on success or %-ENOENT on failure.
- */
-int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
- struct notifier_block *n)
-{
- return notifier_chain_unregister(&nh->head, n);
-}
-
-EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);
-
-/**
- * __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);
-
-/*
- * 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);
-
-/**
- * register_reboot_notifier - Register function to be called at reboot time
- * @nb: Info about notifier function to be called
- *
- * Registers a function with the list of functions
- * to be called at reboot time.
- *
- * Currently always returns zero, as blocking_notifier_chain_register()
- * always returns zero.
- */
-
-int register_reboot_notifier(struct notifier_block * nb)
-{
- return blocking_notifier_chain_register(&reboot_notifier_list, nb);
-}
-
-EXPORT_SYMBOL(register_reboot_notifier);
-
-/**
- * unregister_reboot_notifier - Unregister previously registered reboot notifier
- * @nb: Hook to be unregistered
- *
- * Unregisters a previously registered reboot
- * notifier function.
- *
- * Returns zero on success, or %-ENOENT on failure.
- */
-
-int unregister_reboot_notifier(struct notifier_block * nb)
-{
- return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
-}
-
-EXPORT_SYMBOL(unregister_reboot_notifier);
-
static int set_one_prio(struct task_struct *p, int niceval, int error)
{
int no_nice;
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