Quelle notifier.c Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/kdebug.h>
#include <linux/kprobes.h>
#include <linux/export.h>
#include <linux/notifier.h>
#include <linux/rcupdate.h>
#include <linux/vmalloc.h>

#define CREATE_TRACE_POINTS
#include <trace/events/notifier.h>

/*
* 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,
       bool unique_priority)
{
while ((*nl) != NULL) {
  if (unlikely((*nl) == n)) {
   WARN(1, "notifier callback %ps already registered",
        n->notifier_call);
   return -EEXIST;
  }
  if (n->priority > (*nl)->priority)
   break;
  if (n->priority == (*nl)->priority && unique_priority)
   return -EBUSY;
  nl = &((*nl)->next);
}
n->next = *nl;
rcu_assign_pointer(*nl, n);
trace_notifier_register((void *)n->notifier_call);
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);
   trace_notifier_unregister((void *)n->notifier_call);
   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.
* Return: notifier_call_chain returns the value returned by the
* last notifier function called.
*/
static int 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_raw(*nl);

while (nb && nr_to_call) {
  next_nb = rcu_dereference_raw(nb->next);

#ifdef CONFIG_DEBUG_NOTIFIERS
  if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) {
   WARN(1, "Invalid notifier called!");
   nb = next_nb;
   continue;
  }
#endif
  trace_notifier_run((void *)nb->notifier_call);
  ret = nb->notifier_call(nb, val, v);

  if (nr_calls)
   (*nr_calls)++;

  if (ret & NOTIFY_STOP_MASK)
   break;
  nb = next_nb;
  nr_to_call--;
}
return ret;
}
NOKPROBE_SYMBOL(notifier_call_chain);

/**
* notifier_call_chain_robust - Inform the registered notifiers about an event
*                              and rollback on error.
* @nl: Pointer to head of the blocking notifier chain
* @val_up: Value passed unmodified to the notifier function
* @val_down: Value passed unmodified to the notifier function when recovering
*              from an error on @val_up
* @v: Pointer passed unmodified to the notifier function
*
* NOTE: It is important the @nl chain doesn't change between the two
* invocations of notifier_call_chain() such that we visit the
* exact same notifier callbacks; this rules out any RCU usage.
*
* Return: the return value of the @val_up call.
*/
static int notifier_call_chain_robust(struct notifier_block **nl,
         unsigned long val_up, unsigned long val_down,
         void *v)
{
int ret, nr = 0;

ret = notifier_call_chain(nl, val_up, v, -1, &nr);
if (ret & NOTIFY_STOP_MASK)
  notifier_call_chain(nl, val_down, v, nr-1, NULL);

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.
*
* Returns 0 on success, %-EEXIST on error.
*/
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, false);
spin_unlock_irqrestore(&nh->lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);

/**
* atomic_notifier_chain_register_unique_prio - 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 if there is no other
* notifier registered using the same priority.
*
* Returns 0 on success, %-EEXIST or %-EBUSY on error.
*/
int atomic_notifier_chain_register_unique_prio(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, true);
spin_unlock_irqrestore(&nh->lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(atomic_notifier_chain_register_unique_prio);

/**
* 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
*
* 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 atomic_notifier_call_chain(struct atomic_notifier_head *nh,
          unsigned long val, void *v)
{
int ret;

rcu_read_lock();
ret = notifier_call_chain(&nh->head, val, v, -1, NULL);
rcu_read_unlock();

return ret;
}
EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);
NOKPROBE_SYMBOL(atomic_notifier_call_chain);

/**
* atomic_notifier_call_chain_is_empty - Check whether notifier chain is empty
* @nh: Pointer to head of the atomic notifier chain
*
* Checks whether notifier chain is empty.
*
* Returns true is notifier chain is empty, false otherwise.
*/
bool atomic_notifier_call_chain_is_empty(struct atomic_notifier_head *nh)
{
return !rcu_access_pointer(nh->head);
}

/*
* Blocking notifier chain routines.  All access to the chain is
* synchronized by an rwsem.
*/

static int __blocking_notifier_chain_register(struct blocking_notifier_head *nh,
           struct notifier_block *n,
           bool unique_priority)
{
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, unique_priority);

down_write(&nh->rwsem);
ret = notifier_chain_register(&nh->head, n, unique_priority);
up_write(&nh->rwsem);
return ret;
}

/**
* 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.
*
* Returns 0 on success, %-EEXIST on error.
*/
int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
  struct notifier_block *n)
{
return __blocking_notifier_chain_register(nh, n, false);
}
EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);

/**
* blocking_notifier_chain_register_unique_prio - 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 an blocking notifier chain if there is no other
* notifier registered using the same priority.
*
* Returns 0 on success, %-EEXIST or %-EBUSY on error.
*/
int blocking_notifier_chain_register_unique_prio(struct blocking_notifier_head *nh,
       struct notifier_block *n)
{
return __blocking_notifier_chain_register(nh, n, true);
}
EXPORT_SYMBOL_GPL(blocking_notifier_chain_register_unique_prio);

/**
* 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);

int blocking_notifier_call_chain_robust(struct blocking_notifier_head *nh,
  unsigned long val_up, unsigned long val_down, void *v)
{
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_access_pointer(nh->head)) {
  down_read(&nh->rwsem);
  ret = notifier_call_chain_robust(&nh->head, val_up, val_down, v);
  up_read(&nh->rwsem);
}
return ret;
}
EXPORT_SYMBOL_GPL(blocking_notifier_call_chain_robust);

/**
* 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
*
* 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 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_access_pointer(nh->head)) {
  down_read(&nh->rwsem);
  ret = notifier_call_chain(&nh->head, val, v, -1, NULL);
  up_read(&nh->rwsem);
}
return ret;
}
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.
*
* Returns 0 on success, %-EEXIST on error.
*/
int raw_notifier_chain_register(struct raw_notifier_head *nh,
  struct notifier_block *n)
{
return notifier_chain_register(&nh->head, n, false);
}
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);

int raw_notifier_call_chain_robust(struct raw_notifier_head *nh,
  unsigned long val_up, unsigned long val_down, void *v)
{
return notifier_call_chain_robust(&nh->head, val_up, val_down, v);
}
EXPORT_SYMBOL_GPL(raw_notifier_call_chain_robust);

/**
* 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
*
* 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)
{
return notifier_call_chain(&nh->head, 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.
*
* Returns 0 on success, %-EEXIST on error.
*/
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, false);

mutex_lock(&nh->mutex);
ret = notifier_chain_register(&nh->head, n, false);
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
*
* 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 ret;
int idx;

idx = srcu_read_lock(&nh->srcu);
ret = notifier_call_chain(&nh->head, val, v, -1, NULL);
srcu_read_unlock(&nh->srcu, idx);
return ret;
}
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);

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)
{
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);

quality97%

¤ Dauer der Verarbeitung: 0.4 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.