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rcu: Move rcu_barrier_mutex to rcu_state structure 

In order to allow each RCU flavor to concurrently execute its
rcu_barrier() function, it is necessary to move the relevant
state to the rcu_state structure.  This commit therefore moves the
rcu_barrier_mutex global variable to a new ->barrier_mutex field
in the rcu_state structure.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2012-05-29 05:18:53 -07:00 committed by Paul E. McKenney
parent 7db74df88b
commit 7be7f0be90
2 changed files with 4 additions and 6 deletions
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9
kernel/rcutree.c
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@ -71,6 +71,7 @@ static struct lock_class_key rcu_node_class[RCU_NUM_LVLS];
.onofflock = __RAW_SPIN_LOCK_UNLOCKED(&sname##_state.onofflock), \
.orphan_nxttail = &sname##_state.orphan_nxtlist, \
.orphan_donetail = &sname##_state.orphan_donelist, \
.barrier_mutex = __MUTEX_INITIALIZER(sname##_state.barrier_mutex), \
.fqslock = __RAW_SPIN_LOCK_UNLOCKED(&sname##_state.fqslock), \
.n_force_qs = 0, \
.n_force_qs_ngp = 0, \
@ -155,10 +156,6 @@ static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp);
unsigned long rcutorture_testseq;
unsigned long rcutorture_vernum;
/* State information for rcu_barrier() and friends. */
static DEFINE_MUTEX(rcu_barrier_mutex);
/*
* Return true if an RCU grace period is in progress. The ACCESS_ONCE()s
* permit this function to be invoked without holding the root rcu_node
@ -2303,7 +2300,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
init_rcu_head_on_stack(&rd.barrier_head);
/* Take mutex to serialize concurrent rcu_barrier() requests. */
mutex_lock(&rcu_barrier_mutex);
mutex_lock(&rsp->barrier_mutex);
smp_mb(); /* Prevent any prior operations from leaking in. */
@ -2380,7 +2377,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
wait_for_completion(&rsp->barrier_completion);
/* Other rcu_barrier() invocations can now safely proceed. */
mutex_unlock(&rcu_barrier_mutex);
mutex_unlock(&rsp->barrier_mutex);
destroy_rcu_head_on_stack(&rd.barrier_head);
}

1
kernel/rcutree.h
View File

@ -400,6 +400,7 @@ struct rcu_state {
struct task_struct *rcu_barrier_in_progress;
/* Task doing rcu_barrier(), */
/* or NULL if no barrier. */
struct mutex barrier_mutex; /* Guards barrier fields. */
atomic_t barrier_cpu_count; /* # CPUs waiting on. */
struct completion barrier_completion; /* Wake at barrier end. */
raw_spinlock_t fqslock; /* Only one task forcing */