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rcu: Simplify association of forced quiescent states with grace periods

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The force_quiescent_state() function also took a snapshot
of the ->completed field, which was as obnoxious as it was in
rcu_sched_qs() and friends.  So snapshot ->gpnum-1.

Also, since the dyntick_record_completed() and
dyntick_recall_completed() functions are now simple assignments
that are independent of CONFIG_NO_HZ, and since their names are
now misleading, get rid of them.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <12580941042308-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Paul E. McKenney 2009-11-12 22:35:04 -08:00 committed by Ingo Molnar
parent b32e9eb6ad
commit 8e9aa8f067
1 changed files with 3 additions and 24 deletions
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27
kernel/rcutree.c
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@ -178,28 +178,8 @@ static struct rcu_node *rcu_get_root(struct rcu_state *rsp)
return &rsp->node[0];
}
/*
* Record the specified "completed" value, which is later used to validate
* dynticks counter manipulations and CPU-offline checks. Specify
* "rsp->completed - 1" to unconditionally invalidate any future dynticks
* manipulations and CPU-offline checks. Such invalidation is useful at
* the beginning of a grace period.
*/
static void dyntick_record_completed(struct rcu_state *rsp, long comp)
{
rsp->completed_fqs = comp;
}
#ifdef CONFIG_SMP
/*
* Recall the previously recorded value of the completion for dynticks.
*/
static long dyntick_recall_completed(struct rcu_state *rsp)
{
return rsp->completed_fqs;
}
/*
* If the specified CPU is offline, tell the caller that it is in
* a quiescent state. Otherwise, whack it with a reschedule IPI.
@ -702,7 +682,6 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */
rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
record_gp_stall_check_time(rsp);
dyntick_record_completed(rsp, rsp->completed - 1);
/* Special-case the common single-level case. */
if (NUM_RCU_NODES == 1) {
@ -1214,7 +1193,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
goto unlock_ret; /* no emergency and done recently. */
rsp->n_force_qs++;
spin_lock(&rnp->lock);
lastcomp = rsp->completed;
lastcomp = rsp->gpnum - 1;
signaled = rsp->signaled;
rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
if (lastcomp == rsp->gpnum) {
@ -1248,7 +1227,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
if (lastcomp == rsp->completed &&
rsp->signaled == signaled) {
rsp->signaled = RCU_FORCE_QS;
dyntick_record_completed(rsp, lastcomp);
rsp->completed_fqs = lastcomp;
forcenow = signaled == RCU_SAVE_COMPLETED;
}
spin_unlock(&rnp->lock);
@ -1259,7 +1238,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
case RCU_FORCE_QS:
/* Check dyntick-idle state, send IPI to laggarts. */
if (rcu_process_dyntick(rsp, dyntick_recall_completed(rsp),
if (rcu_process_dyntick(rsp, rsp->completed_fqs,
rcu_implicit_dynticks_qs))
goto unlock_ret;