[RFC PATCH 2/6] notifiers: Convert notifier chain to circular doublylinked-list
From: Srivatsa S. Bhat
Date: Wed Jul 25 2012 - 07:54:09 EST
In order to support invoking the notifiers in the reverse order, we need to
be able to traverse the callback chain in both directions. So convert the
notifier list into a circular doubly linked list.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
---
arch/mips/powertv/powertv_setup.c | 2
arch/um/drivers/mconsole_kern.c | 2
arch/um/kernel/um_arch.c | 2
drivers/acpi/sleep.c | 2
drivers/char/ipmi/ipmi_msghandler.c | 2
drivers/char/ipmi/ipmi_watchdog.c | 4 -
drivers/firmware/dcdbas.c | 2
drivers/md/md.c | 2
drivers/net/ethernet/intel/igb/igb_main.c | 2
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 2
drivers/net/ethernet/myricom/myri10ge/myri10ge.c | 2
drivers/staging/vt6655/device_main.c | 2
include/linux/notifier.h | 23 +++--
kernel/debug/debug_core.c | 2
kernel/notifier.c | 99 +++++++++++-----------
kernel/trace/trace.c | 2
mm/page-writeback.c | 2
mm/vmstat.c | 4 -
18 files changed, 81 insertions(+), 77 deletions(-)
diff --git a/arch/mips/powertv/powertv_setup.c b/arch/mips/powertv/powertv_setup.c
index 3933c37..bade798 100644
--- a/arch/mips/powertv/powertv_setup.c
+++ b/arch/mips/powertv/powertv_setup.c
@@ -87,7 +87,7 @@ static void register_panic_notifier()
{
static struct notifier_block panic_notifier = {
.notifier_call = panic_handler,
- .next = NULL,
+ .list = LIST_HEAD_INIT(panic_notifier.list),
.priority = INT_MAX
};
atomic_notifier_chain_register(&panic_notifier_list, &panic_notifier);
diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index 88e466b..dea89210 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -898,7 +898,7 @@ static int notify_panic(struct notifier_block *self, unsigned long unused1,
static struct notifier_block panic_exit_notifier = {
.notifier_call = notify_panic,
- .next = NULL,
+ .list = LIST_HEAD_INIT(panic_exit_notifier.list),
.priority = 1
};
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 4db8770..fdd2b78 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -243,7 +243,7 @@ static int panic_exit(struct notifier_block *self, unsigned long unused1,
static struct notifier_block panic_exit_notifier = {
.notifier_call = panic_exit,
- .next = NULL,
+ .list = LIST_HEAD_INIT(panic_exit_notifier.list),
.priority = 0
};
diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 8856102..2fa6147 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -85,7 +85,7 @@ static int tts_notify_reboot(struct notifier_block *this,
static struct notifier_block tts_notifier = {
.notifier_call = tts_notify_reboot,
- .next = NULL,
+ .list = LIST_HEAD_INIT(tts_notifier.list),
.priority = 0,
};
diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 2c29942..5a49739 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -4473,7 +4473,7 @@ static int panic_event(struct notifier_block *this,
static struct notifier_block panic_block = {
.notifier_call = panic_event,
- .next = NULL,
+ .list = LIST_HEAD_INIT(panic_block.list),
.priority = 200 /* priority: INT_MAX >= x >= 0 */
};
diff --git a/drivers/char/ipmi/ipmi_watchdog.c b/drivers/char/ipmi/ipmi_watchdog.c
index 7ed356e..e340cc2 100644
--- a/drivers/char/ipmi/ipmi_watchdog.c
+++ b/drivers/char/ipmi/ipmi_watchdog.c
@@ -1183,7 +1183,7 @@ static int wdog_reboot_handler(struct notifier_block *this,
static struct notifier_block wdog_reboot_notifier = {
.notifier_call = wdog_reboot_handler,
- .next = NULL,
+ .list = LIST_HEAD_INIT(wdog_reboot_notifier.list),
.priority = 0
};
@@ -1212,7 +1212,7 @@ static int wdog_panic_handler(struct notifier_block *this,
static struct notifier_block wdog_panic_notifier = {
.notifier_call = wdog_panic_handler,
- .next = NULL,
+ .list = LIST_HEAD_INIT(wdog_panic_notifier.list),
.priority = 150 /* priority: INT_MAX >= x >= 0 */
};
diff --git a/drivers/firmware/dcdbas.c b/drivers/firmware/dcdbas.c
index ea5ac2d..fcd2334 100644
--- a/drivers/firmware/dcdbas.c
+++ b/drivers/firmware/dcdbas.c
@@ -505,7 +505,7 @@ static int dcdbas_reboot_notify(struct notifier_block *nb, unsigned long code,
static struct notifier_block dcdbas_reboot_nb = {
.notifier_call = dcdbas_reboot_notify,
- .next = NULL,
+ .list = LIST_HEAD_INIT(dcdbas_reboot_nb.list),
.priority = INT_MIN
};
diff --git a/drivers/md/md.c b/drivers/md/md.c
index a4c219e..166c917 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8437,7 +8437,7 @@ static int md_notify_reboot(struct notifier_block *this,
static struct notifier_block md_notifier = {
.notifier_call = md_notify_reboot,
- .next = NULL,
+ .list = LIST_HEAD_INIT(md_notifier.list),
.priority = INT_MAX, /* before any real devices */
};
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index dd3bfe8..8bd87bb 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -197,7 +197,7 @@ static void igb_shutdown(struct pci_dev *);
static int igb_notify_dca(struct notifier_block *, unsigned long, void *);
static struct notifier_block dca_notifier = {
.notifier_call = igb_notify_dca,
- .next = NULL,
+ .list = LIST_HEAD_INIT(dca_notifier.list),
.priority = 0
};
#endif
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 18ca3bc..2f460ff 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -124,7 +124,7 @@ static int ixgbe_notify_dca(struct notifier_block *, unsigned long event,
void *p);
static struct notifier_block dca_notifier = {
.notifier_call = ixgbe_notify_dca,
- .next = NULL,
+ .list = LIST_HEAD_INIT(dca_notifier.list),
.priority = 0
};
#endif
diff --git a/drivers/net/ethernet/myricom/myri10ge/myri10ge.c b/drivers/net/ethernet/myricom/myri10ge/myri10ge.c
index 90153fc..9514d81 100644
--- a/drivers/net/ethernet/myricom/myri10ge/myri10ge.c
+++ b/drivers/net/ethernet/myricom/myri10ge/myri10ge.c
@@ -4197,7 +4197,7 @@ myri10ge_notify_dca(struct notifier_block *nb, unsigned long event, void *p)
static struct notifier_block myri10ge_dca_notifier = {
.notifier_call = myri10ge_notify_dca,
- .next = NULL,
+ .list = LIST_HEAD_INIT(myri10ge_dca_notifier.list),
.priority = 0,
};
#endif /* CONFIG_MYRI10GE_DCA */
diff --git a/drivers/staging/vt6655/device_main.c b/drivers/staging/vt6655/device_main.c
index 3e8283c..c71c2a5 100644
--- a/drivers/staging/vt6655/device_main.c
+++ b/drivers/staging/vt6655/device_main.c
@@ -313,7 +313,7 @@ static int viawget_suspend(struct pci_dev *pcid, pm_message_t state);
static int viawget_resume(struct pci_dev *pcid);
struct notifier_block device_notifier = {
.notifier_call = device_notify_reboot,
- .next = NULL,
+ .list = LIST_HEAD_INIT(device_notifier.list),
.priority = 0,
};
#endif
diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index d65746e..67f9a3a 100644
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -49,40 +49,40 @@
struct notifier_block {
int (*notifier_call)(struct notifier_block *, unsigned long, void *);
- struct notifier_block __rcu *next;
+ struct list_head list;
int priority;
};
struct atomic_notifier_head {
spinlock_t lock;
- struct notifier_block __rcu *head;
+ struct list_head list;
};
struct blocking_notifier_head {
struct rw_semaphore rwsem;
- struct notifier_block __rcu *head;
+ struct list_head list;
};
struct raw_notifier_head {
- struct notifier_block __rcu *head;
+ struct list_head list;
};
struct srcu_notifier_head {
struct mutex mutex;
struct srcu_struct srcu;
- struct notifier_block __rcu *head;
+ struct list_head list;
};
#define ATOMIC_INIT_NOTIFIER_HEAD(name) do { \
spin_lock_init(&(name)->lock); \
- (name)->head = NULL; \
+ INIT_LIST_HEAD(&(name)->list); \
} while (0)
#define BLOCKING_INIT_NOTIFIER_HEAD(name) do { \
init_rwsem(&(name)->rwsem); \
- (name)->head = NULL; \
+ INIT_LIST_HEAD(&(name)->list); \
} while (0)
#define RAW_INIT_NOTIFIER_HEAD(name) do { \
- (name)->head = NULL; \
+ INIT_LIST_HEAD(&(name)->list); \
} while (0)
/* srcu_notifier_heads must be initialized and cleaned up dynamically */
@@ -92,12 +92,13 @@ extern void srcu_init_notifier_head(struct srcu_notifier_head *nh);
#define ATOMIC_NOTIFIER_INIT(name) { \
.lock = __SPIN_LOCK_UNLOCKED(name.lock), \
- .head = NULL }
+ .list = LIST_HEAD_INIT(name.list) }
#define BLOCKING_NOTIFIER_INIT(name) { \
.rwsem = __RWSEM_INITIALIZER((name).rwsem), \
- .head = NULL }
+ .list = LIST_HEAD_INIT(name.list) }
#define RAW_NOTIFIER_INIT(name) { \
- .head = NULL }
+ .list = LIST_HEAD_INIT(name.list) }
+
/* srcu_notifier_heads cannot be initialized statically */
#define ATOMIC_NOTIFIER_HEAD(name) \
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 0557f24..9ac45ba 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -805,7 +805,7 @@ done:
static struct notifier_block dbg_reboot_notifier = {
.notifier_call = dbg_notify_reboot,
- .next = NULL,
+ .list = LIST_HEAD_INIT(dbg_reboot_notifier.list),
.priority = INT_MAX,
};
diff --git a/kernel/notifier.c b/kernel/notifier.c
index 2d5cc4c..ad6feab 100644
--- a/kernel/notifier.c
+++ b/kernel/notifier.c
@@ -18,44 +18,48 @@ BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);
* are layered on top of these, with appropriate locking added.
*/
-static int notifier_chain_register(struct notifier_block **nl,
+static int notifier_chain_register(struct list_head *nl,
struct notifier_block *n)
{
- while ((*nl) != NULL) {
- if (n->priority > (*nl)->priority)
+ struct notifier_block *cur;
+
+ list_for_each_entry(cur, nl, list) {
+ if (n->priority > cur->priority)
break;
- nl = &((*nl)->next);
}
- n->next = *nl;
- rcu_assign_pointer(*nl, n);
+
+ list_add_tail_rcu(&n->list, &cur->list);
return 0;
}
-static int notifier_chain_cond_register(struct notifier_block **nl,
+static int notifier_chain_cond_register(struct list_head *nl,
struct notifier_block *n)
{
- while ((*nl) != NULL) {
- if ((*nl) == n)
+ struct notifier_block *cur;
+
+ list_for_each_entry(cur, nl, list) {
+ if (cur == n)
return 0;
- if (n->priority > (*nl)->priority)
+ if (n->priority > cur->priority)
break;
- nl = &((*nl)->next);
}
- n->next = *nl;
- rcu_assign_pointer(*nl, n);
+
+ list_add_tail_rcu(&n->list, &cur->list);
return 0;
}
-static int notifier_chain_unregister(struct notifier_block **nl,
+static int notifier_chain_unregister(struct list_head *nl,
struct notifier_block *n)
{
- while ((*nl) != NULL) {
- if ((*nl) == n) {
- rcu_assign_pointer(*nl, n->next);
+ struct notifier_block *cur;
+
+ list_for_each_entry(cur, nl, list) {
+ if (cur == n) {
+ list_del_bidir_rcu(&cur->list);
return 0;
}
- nl = &((*nl)->next);
}
+
return -ENOENT;
}
@@ -71,22 +75,20 @@ static int notifier_chain_unregister(struct notifier_block **nl,
* @returns: notifier_call_chain returns the value returned by the
* last notifier function called.
*/
-static int __kprobes notifier_call_chain(struct notifier_block **nl,
+static int __kprobes notifier_call_chain(struct list_head *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);
+ struct notifier_block *nb;
- while (nb && nr_to_call) {
- next_nb = rcu_dereference_raw(nb->next);
+ list_for_each_entry_rcu(nb, nl, list) {
+ if (!nr_to_call)
+ break;
#ifdef CONFIG_DEBUG_NOTIFIERS
if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) {
WARN(1, "Invalid notifier called!");
- nb = next_nb;
continue;
}
#endif
@@ -97,9 +99,9 @@ static int __kprobes notifier_call_chain(struct notifier_block **nl,
if ((ret & NOTIFY_STOP_MASK) == NOTIFY_STOP_MASK)
break;
- nb = next_nb;
nr_to_call--;
}
+
return ret;
}
@@ -124,7 +126,7 @@ int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
int ret;
spin_lock_irqsave(&nh->lock, flags);
- ret = notifier_chain_register(&nh->head, n);
+ ret = notifier_chain_register(&nh->list, n);
spin_unlock_irqrestore(&nh->lock, flags);
return ret;
}
@@ -146,7 +148,7 @@ int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
int ret;
spin_lock_irqsave(&nh->lock, flags);
- ret = notifier_chain_unregister(&nh->head, n);
+ ret = notifier_chain_unregister(&nh->list, n);
spin_unlock_irqrestore(&nh->lock, flags);
synchronize_rcu();
return ret;
@@ -179,7 +181,7 @@ int __kprobes __atomic_notifier_call_chain(struct atomic_notifier_head *nh,
int ret;
rcu_read_lock();
- ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
+ ret = notifier_call_chain(&nh->list, val, v, nr_to_call, nr_calls);
rcu_read_unlock();
return ret;
}
@@ -218,10 +220,10 @@ int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
* such times we must not call down_write().
*/
if (unlikely(system_state == SYSTEM_BOOTING))
- return notifier_chain_register(&nh->head, n);
+ return notifier_chain_register(&nh->list, n);
down_write(&nh->rwsem);
- ret = notifier_chain_register(&nh->head, n);
+ ret = notifier_chain_register(&nh->list, n);
up_write(&nh->rwsem);
return ret;
}
@@ -244,7 +246,7 @@ int blocking_notifier_chain_cond_register(struct blocking_notifier_head *nh,
int ret;
down_write(&nh->rwsem);
- ret = notifier_chain_cond_register(&nh->head, n);
+ ret = notifier_chain_cond_register(&nh->list, n);
up_write(&nh->rwsem);
return ret;
}
@@ -271,10 +273,10 @@ int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
* such times we must not call down_write().
*/
if (unlikely(system_state == SYSTEM_BOOTING))
- return notifier_chain_unregister(&nh->head, n);
+ return notifier_chain_unregister(&nh->list, n);
down_write(&nh->rwsem);
- ret = notifier_chain_unregister(&nh->head, n);
+ ret = notifier_chain_unregister(&nh->list, n);
up_write(&nh->rwsem);
return ret;
}
@@ -305,13 +307,14 @@ int __blocking_notifier_call_chain(struct blocking_notifier_head *nh,
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:
+ * We check whether the list is empty 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_raw(nh->head)) {
+ if (!list_empty(&nh->list)) {
down_read(&nh->rwsem);
- ret = notifier_call_chain(&nh->head, val, v, nr_to_call,
+ ret = notifier_call_chain(&nh->list, val, v, nr_to_call,
nr_calls);
up_read(&nh->rwsem);
}
@@ -344,7 +347,7 @@ EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);
int raw_notifier_chain_register(struct raw_notifier_head *nh,
struct notifier_block *n)
{
- return notifier_chain_register(&nh->head, n);
+ return notifier_chain_register(&nh->list, n);
}
EXPORT_SYMBOL_GPL(raw_notifier_chain_register);
@@ -361,7 +364,7 @@ EXPORT_SYMBOL_GPL(raw_notifier_chain_register);
int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
struct notifier_block *n)
{
- return notifier_chain_unregister(&nh->head, n);
+ return notifier_chain_unregister(&nh->list, n);
}
EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);
@@ -388,7 +391,7 @@ 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);
+ return notifier_call_chain(&nh->list, val, v, nr_to_call, nr_calls);
}
EXPORT_SYMBOL_GPL(__raw_notifier_call_chain);
@@ -425,10 +428,10 @@ int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
* such times we must not call mutex_lock().
*/
if (unlikely(system_state == SYSTEM_BOOTING))
- return notifier_chain_register(&nh->head, n);
+ return notifier_chain_register(&nh->list, n);
mutex_lock(&nh->mutex);
- ret = notifier_chain_register(&nh->head, n);
+ ret = notifier_chain_register(&nh->list, n);
mutex_unlock(&nh->mutex);
return ret;
}
@@ -455,10 +458,10 @@ int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
* such times we must not call mutex_lock().
*/
if (unlikely(system_state == SYSTEM_BOOTING))
- return notifier_chain_unregister(&nh->head, n);
+ return notifier_chain_unregister(&nh->list, n);
mutex_lock(&nh->mutex);
- ret = notifier_chain_unregister(&nh->head, n);
+ ret = notifier_chain_unregister(&nh->list, n);
mutex_unlock(&nh->mutex);
synchronize_srcu(&nh->srcu);
return ret;
@@ -491,7 +494,7 @@ int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
int idx;
idx = srcu_read_lock(&nh->srcu);
- ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls);
+ ret = notifier_call_chain(&nh->list, val, v, nr_to_call, nr_calls);
srcu_read_unlock(&nh->srcu, idx);
return ret;
}
@@ -521,7 +524,7 @@ 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;
+ INIT_LIST_HEAD(&nh->list);
}
EXPORT_SYMBOL_GPL(srcu_init_notifier_head);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a7fa070..9feadb8 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4876,7 +4876,7 @@ static int trace_panic_handler(struct notifier_block *this,
static struct notifier_block trace_panic_notifier = {
.notifier_call = trace_panic_handler,
- .next = NULL,
+ .list = LIST_HEAD_INIT(trace_panic_notifier.list),
.priority = 150 /* priority: INT_MAX >= x >= 0 */
};
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 93d8d2f..4135c16 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1583,7 +1583,7 @@ ratelimit_handler(struct notifier_block *self, unsigned long u, void *v)
static struct notifier_block __cpuinitdata ratelimit_nb = {
.notifier_call = ratelimit_handler,
- .next = NULL,
+ .list = LIST_HEAD_INIT(ratelimit_nb.list),
};
/*
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 1bbbbd9..ad67df0 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1196,8 +1196,8 @@ static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
return NOTIFY_OK;
}
-static struct notifier_block __cpuinitdata vmstat_notifier =
- { &vmstat_cpuup_callback, NULL, 0 };
+static struct notifier_block __cpuinitdata vmstat_notifier = {
+ &vmstat_cpuup_callback, LIST_HEAD_INIT(vmstat_notifier.list), 0 };
#endif
static int __init setup_vmstat(void)
--
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