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rcu: Move rcu_barrier_cpu_count 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_cpu_count global
variable to a new ->barrier_cpu_count 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>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Paul E. McKenney 2012-05-29 00:34:56 -07:00 committed by Paul E. McKenney
parent 06668efa91
commit 24ebbca8ec
2 changed files with 15 additions and 11 deletions
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25
kernel/rcutree.c
View File

@ -157,7 +157,6 @@ unsigned long rcutorture_vernum;
/* State information for rcu_barrier() and friends. */
static atomic_t rcu_barrier_cpu_count;
static DEFINE_MUTEX(rcu_barrier_mutex);
static struct completion rcu_barrier_completion;
@ -2270,9 +2269,12 @@ static int rcu_cpu_has_callbacks(int cpu)
* RCU callback function for _rcu_barrier(). If we are last, wake
* up the task executing _rcu_barrier().
*/
static void rcu_barrier_callback(struct rcu_head *notused)
static void rcu_barrier_callback(struct rcu_head *rhp)
{
if (atomic_dec_and_test(&rcu_barrier_cpu_count))
struct rcu_data *rdp = container_of(rhp, struct rcu_data, barrier_head);
struct rcu_state *rsp = rdp->rsp;
if (atomic_dec_and_test(&rsp->barrier_cpu_count))
complete(&rcu_barrier_completion);
}
@ -2284,7 +2286,7 @@ static void rcu_barrier_func(void *type)
struct rcu_state *rsp = type;
struct rcu_data *rdp = __this_cpu_ptr(rsp->rda);
atomic_inc(&rcu_barrier_cpu_count);
atomic_inc(&rsp->barrier_cpu_count);
rsp->call(&rdp->barrier_head, rcu_barrier_callback);
}
@ -2297,9 +2299,9 @@ static void _rcu_barrier(struct rcu_state *rsp)
int cpu;
unsigned long flags;
struct rcu_data *rdp;
struct rcu_head rh;
struct rcu_data rd;
init_rcu_head_on_stack(&rh);
init_rcu_head_on_stack(&rd.barrier_head);
/* Take mutex to serialize concurrent rcu_barrier() requests. */
mutex_lock(&rcu_barrier_mutex);
@ -2324,7 +2326,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
* us -- but before CPU 1's orphaned callbacks are invoked!!!
*/
init_completion(&rcu_barrier_completion);
atomic_set(&rcu_barrier_cpu_count, 1);
atomic_set(&rsp->barrier_cpu_count, 1);
raw_spin_lock_irqsave(&rsp->onofflock, flags);
rsp->rcu_barrier_in_progress = current;
raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
@ -2363,15 +2365,16 @@ static void _rcu_barrier(struct rcu_state *rsp)
rcu_adopt_orphan_cbs(rsp);
rsp->rcu_barrier_in_progress = NULL;
raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
atomic_inc(&rcu_barrier_cpu_count);
atomic_inc(&rsp->barrier_cpu_count);
smp_mb__after_atomic_inc(); /* Ensure atomic_inc() before callback. */
rsp->call(&rh, rcu_barrier_callback);
rd.rsp = rsp;
rsp->call(&rd.barrier_head, rcu_barrier_callback);
/*
* Now that we have an rcu_barrier_callback() callback on each
* CPU, and thus each counted, remove the initial count.
*/
if (atomic_dec_and_test(&rcu_barrier_cpu_count))
if (atomic_dec_and_test(&rsp->barrier_cpu_count))
complete(&rcu_barrier_completion);
/* Wait for all rcu_barrier_callback() callbacks to be invoked. */
@ -2380,7 +2383,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
/* Other rcu_barrier() invocations can now safely proceed. */
mutex_unlock(&rcu_barrier_mutex);
destroy_rcu_head_on_stack(&rh);
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. */
atomic_t barrier_cpu_count; /* # CPUs waiting on. */
raw_spinlock_t fqslock; /* Only one task forcing */
/* quiescent states. */
unsigned long jiffies_force_qs; /* Time at which to invoke */