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Subject[RFC PATCH 02/11] sched: Restructure destroy_sched_domain()
Date
From: Peter Zijlstra <peterz@infradead.org>

There is no point in doing a call_rcu() for each domain, only do a
callback for the root sched domain and clean up the entire set in one
go.

Also make the entire call chain be called destroy_sched_domain*() to
remove confusion with the free_sched_domains() call, which does an
entirely different thing.

Both cpu_attach_domain() callers of destroy_sched_domain() can live
without the call_rcu() because at those points the sched_domain hasn't
been published yet.

This one seems to work much better; so much for last minute 'cleanups'.
---
kernel/sched/core.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ab6e6cf..c4596e0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5833,10 +5833,8 @@ static void free_sched_groups(struct sched_group *sg, int free_sgc)
} while (sg != first);
}

-static void free_sched_domain(struct rcu_head *rcu)
+static void destroy_sched_domain(struct sched_domain *sd)
{
- struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
-
/*
* If its an overlapping domain it has private groups, iterate and
* nuke them all.
@@ -5850,15 +5848,21 @@ static void free_sched_domain(struct rcu_head *rcu)
kfree(sd);
}

-static void destroy_sched_domain(struct sched_domain *sd)
+static void destroy_sched_domains_rcu(struct rcu_head *rcu)
{
- call_rcu(&sd->rcu, free_sched_domain);
+ struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
+
+ while (sd) {
+ struct sched_domain *parent = sd->parent;
+ destroy_sched_domain(sd);
+ sd = parent;
+ }
}

static void destroy_sched_domains(struct sched_domain *sd)
{
- for (; sd; sd = sd->parent)
- destroy_sched_domain(sd);
+ if (sd)
+ call_rcu(&sd->rcu, destroy_sched_domains_rcu);
}

/*
--
1.7.9.5
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