[PATCH] srcu: Isolate srcu sections using CONFIG_SRCU
From: Pranith Kumar
Date: Tue Dec 09 2014 - 13:48:28 EST
Isolate the SRCU functions and data structures within CONFIG_SRCU so that there
is a compile time failure if srcu is used when not enabled. This was decided to
be better than waiting until link time for a failure to occur.
Also make including kvm_host.h conditional on CONFIG_KVM being enabled. This
prevents build failures as KVM is dependent on SRCU.
Signed-off-by: Pranith Kumar <bobby.prani@xxxxxxxxx>
CC: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CC: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
CC: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
arch/s390/kernel/asm-offsets.c | 7 ++++++-
include/linux/notifier.h | 47 ++++++++++++++++++++++++------------------
include/linux/srcu.h | 6 +++++-
3 files changed, 38 insertions(+), 22 deletions(-)
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index ef279a1..2813a3c 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -7,12 +7,15 @@
#define ASM_OFFSETS_C
#include <linux/kbuild.h>
-#include <linux/kvm_host.h>
#include <linux/sched.h>
#include <asm/idle.h>
#include <asm/vdso.h>
#include <asm/pgtable.h>
+#if IS_ENABLED(CONFIG_KVM)
+#include <linux/kvm_host.h>
+#endif
+
/*
* Make sure that the compiler is new enough. We want a compiler that
* is known to work with the "Q" assembler constraint.
@@ -182,8 +185,10 @@ int main(void)
DEFINE(__LC_PGM_TDB, offsetof(struct _lowcore, pgm_tdb));
DEFINE(__THREAD_trap_tdb, offsetof(struct task_struct, thread.trap_tdb));
DEFINE(__GMAP_ASCE, offsetof(struct gmap, asce));
+#if IS_ENABLED(CONFIG_KVM)
DEFINE(__SIE_PROG0C, offsetof(struct kvm_s390_sie_block, prog0c));
DEFINE(__SIE_PROG20, offsetof(struct kvm_s390_sie_block, prog20));
+#endif /* CONFIG_KVM */
#endif /* CONFIG_32BIT */
return 0;
}
diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index d14a4c3..fe4f02a 100644
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -47,6 +47,8 @@
* runtime initialization.
*/
+struct notifier_block;
+
typedef int (*notifier_fn_t)(struct notifier_block *nb,
unsigned long action, void *data);
@@ -70,12 +72,6 @@ struct raw_notifier_head {
struct notifier_block __rcu *head;
};
-struct srcu_notifier_head {
- struct mutex mutex;
- struct srcu_struct srcu;
- struct notifier_block __rcu *head;
-};
-
#define ATOMIC_INIT_NOTIFIER_HEAD(name) do { \
spin_lock_init(&(name)->lock); \
(name)->head = NULL; \
@@ -88,11 +84,6 @@ struct srcu_notifier_head {
(name)->head = NULL; \
} while (0)
-/* srcu_notifier_heads must be initialized and 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);
-
#define ATOMIC_NOTIFIER_INIT(name) { \
.lock = __SPIN_LOCK_UNLOCKED(name.lock), \
.head = NULL }
@@ -101,7 +92,6 @@ 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 ATOMIC_NOTIFIER_HEAD(name) \
struct atomic_notifier_head name = \
@@ -121,8 +111,6 @@ extern int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
struct notifier_block *nb);
extern int raw_notifier_chain_register(struct raw_notifier_head *nh,
struct notifier_block *nb);
-extern int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
- struct notifier_block *nb);
extern int blocking_notifier_chain_cond_register(
struct blocking_notifier_head *nh,
@@ -134,8 +122,6 @@ extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
struct notifier_block *nb);
extern int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
struct notifier_block *nb);
-extern int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
- struct notifier_block *nb);
extern int atomic_notifier_call_chain(struct atomic_notifier_head *nh,
unsigned long val, void *v);
@@ -149,10 +135,6 @@ extern int raw_notifier_call_chain(struct raw_notifier_head *nh,
unsigned long val, void *v);
extern int __raw_notifier_call_chain(struct raw_notifier_head *nh,
unsigned long val, void *v, int nr_to_call, int *nr_calls);
-extern int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
- unsigned long val, void *v);
-extern int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
- unsigned long val, void *v, int nr_to_call, int *nr_calls);
#define NOTIFY_DONE 0x0000 /* Don't care */
#define NOTIFY_OK 0x0001 /* Suits me */
@@ -211,5 +193,30 @@ static inline int notifier_to_errno(int ret)
extern struct blocking_notifier_head reboot_notifier_list;
+#ifdef CONFIG_SRCU
+
+struct srcu_notifier_head {
+ struct mutex mutex;
+ struct srcu_struct srcu;
+ struct notifier_block __rcu *head;
+};
+
+/* srcu_notifier_heads must be initialized and cleaned up dynamically
+ * srcu_notifier_heads cannot be initialized statically
+ */
+extern void srcu_init_notifier_head(struct srcu_notifier_head *nh);
+#define srcu_cleanup_notifier_head(name) cleanup_srcu_struct(&(name)->srcu)
+
+extern int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
+ struct notifier_block *nb);
+extern int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
+ struct notifier_block *nb);
+extern int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
+ unsigned long val, void *v);
+extern int __srcu_notifier_call_chain(struct srcu_notifier_head *nh,
+ unsigned long val, void *v, int nr_to_call, int *nr_calls);
+
+#endif /* CONFIG_SRCU */
+
#endif /* __KERNEL__ */
#endif /* _LINUX_NOTIFIER_H */
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 9cfd962..ed9c389 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -26,6 +26,8 @@
*
*/
+#ifdef CONFIG_SRCU
+
#ifndef _LINUX_SRCU_H
#define _LINUX_SRCU_H
@@ -249,4 +251,6 @@ static inline void smp_mb__after_srcu_read_unlock(void)
/* __srcu_read_unlock has smp_mb() internally so nothing to do here. */
}
-#endif
+#endif /* _LINUX_SRCU_H */
+
+#endif /* CONFIG_SRCU */
--
1.9.1
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