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Subject[PATCH 1/2] kernel/SRCU: provide a static initializer
Date
There are macros for static initializer for the three out of four
possible notifier types, that are:
ATOMIC_NOTIFIER_HEAD()
BLOCKING_NOTIFIER_HEAD()
RAW_NOTIFIER_HEAD()

This patch provides a static initilizer for the forth type to make it
complete.

Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/notifier.h | 34 +++++++++++++++++++++++++++++-----
include/linux/srcutiny.h | 6 +++---
include/linux/srcutree.h | 6 +++---
3 files changed, 35 insertions(+), 11 deletions(-)

diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index 6d731110e0db..f35c7bf76143 100644
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -43,9 +43,7 @@
* in srcu_notifier_call_chain(): no cache bounces and no memory barriers.
* As compensation, srcu_notifier_chain_unregister() is rather expensive.
* SRCU notifier chains should be used when the chain will be called very
- * often but notifier_blocks will seldom be removed. Also, SRCU notifier
- * chains are slightly more difficult to use because they require special
- * runtime initialization.
+ * often but notifier_blocks will seldom be removed.
*/

struct notifier_block;
@@ -91,7 +89,7 @@ struct srcu_notifier_head {
(name)->head = NULL; \
} while (0)

-/* srcu_notifier_heads must be initialized and cleaned up dynamically */
+/* srcu_notifier_heads must be cleaned up dynamically */
extern void srcu_init_notifier_head(struct srcu_notifier_head *nh);
#define srcu_cleanup_notifier_head(name) \
cleanup_srcu_struct(&(name)->srcu);
@@ -104,7 +102,13 @@ extern void srcu_init_notifier_head(struct srcu_notifier_head *nh);
.head = NULL }
#define RAW_NOTIFIER_INIT(name) { \
.head = NULL }
-/* srcu_notifier_heads cannot be initialized statically */
+
+#define SRCU_NOTIFIER_INIT(name, pcpu) \
+ { \
+ .mutex = __MUTEX_INITIALIZER(name.mutex), \
+ .head = NULL, \
+ .srcu = __SRCU_STRUCT_INIT(name.srcu, pcpu), \
+ }

#define ATOMIC_NOTIFIER_HEAD(name) \
struct atomic_notifier_head name = \
@@ -116,6 +120,26 @@ extern void srcu_init_notifier_head(struct srcu_notifier_head *nh);
struct raw_notifier_head name = \
RAW_NOTIFIER_INIT(name)

+#ifdef CONFIG_TREE_SRCU
+#define _SRCU_NOTIFIER_HEAD(name, mod) \
+ static DEFINE_PER_CPU(struct srcu_data, \
+ name##_head_srcu_data); \
+ mod struct srcu_notifier_head name = \
+ SRCU_NOTIFIER_INIT(name, name##_head_srcu_data)
+
+#else
+#define _SRCU_NOTIFIER_HEAD(name, mod) \
+ mod struct srcu_notifier_head name = \
+ SRCU_NOTIFIER_INIT(name, name)
+
+#endif
+
+#define SRCU_NOTIFIER_HEAD(name) \
+ _SRCU_NOTIFIER_HEAD(name, /* not static */)
+
+#define SRCU_NOTIFIER_HEAD_STATIC(name) \
+ _SRCU_NOTIFIER_HEAD(name, static)
+
#ifdef __KERNEL__

extern int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h
index 261471f407a5..f41d2fb09f87 100644
--- a/include/linux/srcutiny.h
+++ b/include/linux/srcutiny.h
@@ -43,7 +43,7 @@ struct srcu_struct {

void srcu_drive_gp(struct work_struct *wp);

-#define __SRCU_STRUCT_INIT(name) \
+#define __SRCU_STRUCT_INIT(name, __ignored) \
{ \
.srcu_wq = __SWAIT_QUEUE_HEAD_INITIALIZER(name.srcu_wq), \
.srcu_cb_tail = &name.srcu_cb_head, \
@@ -56,9 +56,9 @@ void srcu_drive_gp(struct work_struct *wp);
* Tree SRCU, which needs some per-CPU data.
*/
#define DEFINE_SRCU(name) \
- struct srcu_struct name = __SRCU_STRUCT_INIT(name)
+ struct srcu_struct name = __SRCU_STRUCT_INIT(name, name)
#define DEFINE_STATIC_SRCU(name) \
- static struct srcu_struct name = __SRCU_STRUCT_INIT(name)
+ static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name)

void synchronize_srcu(struct srcu_struct *sp);

diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 4eda108abee0..745d4ca4dd50 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -104,9 +104,9 @@ struct srcu_struct {
#define SRCU_STATE_SCAN1 1
#define SRCU_STATE_SCAN2 2

-#define __SRCU_STRUCT_INIT(name) \
+#define __SRCU_STRUCT_INIT(name, pcpu_name) \
{ \
- .sda = &name##_srcu_data, \
+ .sda = &pcpu_name, \
.lock = __SPIN_LOCK_UNLOCKED(name.lock), \
.srcu_gp_seq_needed = 0 - 1, \
__SRCU_DEP_MAP_INIT(name) \
@@ -133,7 +133,7 @@ struct srcu_struct {
*/
#define __DEFINE_SRCU(name, is_static) \
static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data);\
- is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name)
+ is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name##_srcu_data)
#define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */)
#define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static)

--
2.17.0
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