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srcu: Create a tiny SRCU

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In response to automated complaints about modifications to SRCU
increasing its size, this commit creates a tiny SRCU that is
used in SMP=n && PREEMPT=n builds.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2017-03-25 09:59:38 -07:00
parent dde8da6cff
commit d8be81735a
7 changed files with 411 additions and 62 deletions
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69
include/linux/srcu.h
View file

@ -34,28 +34,7 @@
#include <linux/workqueue.h>
#include <linux/rcu_segcblist.h>
struct srcu_array {
unsigned long lock_count[2];
unsigned long unlock_count[2];
};
struct srcu_struct {
unsigned long completed;
unsigned long srcu_gp_seq;
atomic_t srcu_exp_cnt;
struct srcu_array __percpu *per_cpu_ref;
spinlock_t queue_lock; /* protect ->srcu_cblist */
struct rcu_segcblist srcu_cblist;
struct delayed_work work;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
};
/* Values for -> state variable. */
#define SRCU_STATE_IDLE 0
#define SRCU_STATE_SCAN1 1
#define SRCU_STATE_SCAN2 2
struct srcu_struct;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
@ -77,42 +56,13 @@ int init_srcu_struct(struct srcu_struct *sp);
#define __SRCU_DEP_MAP_INIT(srcu_name)
#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
void process_srcu(struct work_struct *work);
#define __SRCU_STRUCT_INIT(name) \
{ \
.completed = -300, \
.per_cpu_ref = &name##_srcu_array, \
.queue_lock = __SPIN_LOCK_UNLOCKED(name.queue_lock), \
.srcu_cblist = RCU_SEGCBLIST_INITIALIZER(name.srcu_cblist),\
.work = __DELAYED_WORK_INITIALIZER(name.work, process_srcu, 0),\
__SRCU_DEP_MAP_INIT(name) \
}
/*
* Define and initialize a srcu struct at build time.
* Do -not- call init_srcu_struct() nor cleanup_srcu_struct() on it.
*
* Note that although DEFINE_STATIC_SRCU() hides the name from other
* files, the per-CPU variable rules nevertheless require that the
* chosen name be globally unique. These rules also prohibit use of
* DEFINE_STATIC_SRCU() within a function. If these rules are too
* restrictive, declare the srcu_struct manually. For example, in
* each file:
*
* static struct srcu_struct my_srcu;
*
* Then, before the first use of each my_srcu, manually initialize it:
*
* init_srcu_struct(&my_srcu);
*
* See include/linux/percpu-defs.h for the rules on per-CPU variables.
*/
#define __DEFINE_SRCU(name, is_static) \
static DEFINE_PER_CPU(struct srcu_array, name##_srcu_array);\
is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name)
#define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */)
#define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static)
#ifdef CONFIG_TINY_SRCU
#include <linux/srcutiny.h>
#elif defined(CONFIG_TREE_SRCU)
#include <linux/srcutree.h>
#else
#error "Unknown SRCU implementation specified to kernel configuration"
#endif
/**
* call_srcu() - Queue a callback for invocation after an SRCU grace period
@ -138,9 +88,6 @@ void cleanup_srcu_struct(struct srcu_struct *sp);
int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp);
void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp);
void synchronize_srcu(struct srcu_struct *sp);
void synchronize_srcu_expedited(struct srcu_struct *sp);
unsigned long srcu_batches_completed(struct srcu_struct *sp);
void srcu_barrier(struct srcu_struct *sp);
#ifdef CONFIG_DEBUG_LOCK_ALLOC