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rcu: Consolidate expedited grace period machinery 

The functions synchronize_rcu_expedited() and synchronize_sched_expedited()
have nearly identical code.  This commit therefore consolidates this code
into a new _synchronize_rcu_expedited() function.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2016-06-24 11:30:32 -07:00
parent 29b4817d40
commit f7b8eb847e
1 changed files with 29 additions and 33 deletions
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62
kernel/rcu/tree_exp.h
View File

@ -516,6 +516,33 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s)
mutex_unlock(&rsp->exp_wake_mutex);
}
/*
* Given an rcu_state pointer and a smp_call_function() handler, kick
* off the specified flavor of expedited grace period.
*/
static void _synchronize_rcu_expedited(struct rcu_state *rsp,
smp_call_func_t func)
{
unsigned long s;
/* If expedited grace periods are prohibited, fall back to normal. */
if (rcu_gp_is_normal()) {
wait_rcu_gp(rsp->call);
return;
}
/* Take a snapshot of the sequence number. */
s = rcu_exp_gp_seq_snap(rsp);
if (exp_funnel_lock(rsp, s))
return; /* Someone else did our work for us. */
/* Initialize the rcu_node tree in preparation for the wait. */
sync_rcu_exp_select_cpus(rsp, func);
/* Wait and clean up, including waking everyone. */
rcu_exp_wait_wake(rsp, s);
}
/**
* synchronize_sched_expedited - Brute-force RCU-sched grace period
*
@ -534,29 +561,13 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s)
*/
void synchronize_sched_expedited(void)
{
unsigned long s;
struct rcu_state *rsp = &rcu_sched_state;
/* If only one CPU, this is automatically a grace period. */
if (rcu_blocking_is_gp())
return;
/* If expedited grace periods are prohibited, fall back to normal. */
if (rcu_gp_is_normal()) {
wait_rcu_gp(call_rcu_sched);
return;
}
/* Take a snapshot of the sequence number. */
s = rcu_exp_gp_seq_snap(rsp);
if (exp_funnel_lock(rsp, s))
return; /* Someone else did our work for us. */
/* Initialize the rcu_node tree in preparation for the wait. */
sync_rcu_exp_select_cpus(rsp, sync_sched_exp_handler);
/* Wait and clean up, including waking everyone. */
rcu_exp_wait_wake(rsp, s);
_synchronize_rcu_expedited(rsp, sync_sched_exp_handler);
}
EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
@ -620,23 +631,8 @@ static void sync_rcu_exp_handler(void *info)
void synchronize_rcu_expedited(void)
{
struct rcu_state *rsp = rcu_state_p;
unsigned long s;
/* If expedited grace periods are prohibited, fall back to normal. */
if (rcu_gp_is_normal()) {
wait_rcu_gp(call_rcu);
return;
}
s = rcu_exp_gp_seq_snap(rsp);
if (exp_funnel_lock(rsp, s))
return; /* Someone else did our work for us. */
/* Initialize the rcu_node tree in preparation for the wait. */
sync_rcu_exp_select_cpus(rsp, sync_rcu_exp_handler);
/* Wait for ->blkd_tasks lists to drain, then wake everyone up. */
rcu_exp_wait_wake(rsp, s);
_synchronize_rcu_expedited(rsp, sync_rcu_exp_handler);
}
EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);