Commit-ID: 0f10dc826646134dce3e5751512b87d30f3903e4
Gitweb: http://git.kernel.org/tip/0f10dc826646134dce3e5751512b87d30f3903e4
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 4 Jan 2010 15:09:06 -0800
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 13 Jan 2010 09:06:03 +0100
rcu: Eliminate rcu_process_dyntick() return value
Because a new grace period cannot start while we are executing
within the force_quiescent_state() function's switch statement,
if any test within that switch statement or within any function
called from that switch statement shows that the current grace
period has ended, we can safely re-do that test any time before
we leave the switch statement. This means that we no longer
need a return value from rcu_process_dyntick(), as we can simply
invoke rcu_gp_in_progress() to check whether the old grace
period has finished -- there is no longer any need to worry
about whether or not a new grace period has been started.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: laijs@xxxxxxxxxxxxxx
Cc: dipankar@xxxxxxxxxx
Cc: mathieu.desnoyers@xxxxxxxxxx
Cc: josh@xxxxxxxxxxxxxxxx
Cc: dvhltc@xxxxxxxxxx
Cc: niv@xxxxxxxxxx
Cc: peterz@xxxxxxxxxxxxx
Cc: rostedt@xxxxxxxxxxx
Cc: Valdis.Kletnieks@xxxxxx
Cc: dhowells@xxxxxxxxxx
LKML-Reference: <12626465501857-git-send-email->
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/rcutree.c | 17 ++++++-----------
1 files changed, 6 insertions(+), 11 deletions(-)
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index c7d0070..e497119 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1144,11 +1144,9 @@ void rcu_check_callbacks(int cpu, int user)
/*
* Scan the leaf rcu_node structures, processing dyntick state for any that
* have not yet encountered a quiescent state, using the function specified.
- * Returns 1 if the current grace period ends while scanning (possibly
- * because we made it end).
*/
-static int rcu_process_dyntick(struct rcu_state *rsp,
- int (*f)(struct rcu_data *))
+static void rcu_process_dyntick(struct rcu_state *rsp,
+ int (*f)(struct rcu_data *))
{
unsigned long bit;
int cpu;
@@ -1161,7 +1159,7 @@ static int rcu_process_dyntick(struct rcu_state *rsp,
spin_lock_irqsave(&rnp->lock, flags);
if (rnp->completed != rsp->gpnum - 1) {
spin_unlock_irqrestore(&rnp->lock, flags);
- return 1;
+ return;
}
if (rnp->qsmask == 0) {
spin_unlock_irqrestore(&rnp->lock, flags);
@@ -1181,7 +1179,6 @@ static int rcu_process_dyntick(struct rcu_state *rsp,
}
spin_unlock_irqrestore(&rnp->lock, flags);
}
- return 0;
}
/*
@@ -1193,7 +1190,6 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
unsigned long flags;
struct rcu_node *rnp = rcu_get_root(rsp);
u8 forcenow;
- u8 gpdone;
if (!rcu_gp_in_progress(rsp))
return; /* No grace period in progress, nothing to force. */
@@ -1226,10 +1222,9 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
break; /* So gcc recognizes the dead code. */
/* Record dyntick-idle state. */
- gpdone = rcu_process_dyntick(rsp,
- dyntick_save_progress_counter);
+ rcu_process_dyntick(rsp, dyntick_save_progress_counter);
spin_lock(&rnp->lock); /* irqs already disabled */
- if (gpdone)
+ if (!rcu_gp_in_progress(rsp))
break;
/* fall into next case. */
@@ -1249,7 +1244,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
/* Check dyntick-idle state, send IPI to laggarts. */
spin_unlock(&rnp->lock); /* irqs remain disabled */
- gpdone = rcu_process_dyntick(rsp, rcu_implicit_dynticks_qs);
+ rcu_process_dyntick(rsp, rcu_implicit_dynticks_qs);
/* Leave state in case more forcing is required. */
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|