[systemd-devel] [PATCH 2/2] domain: grab the domain's parent lock only when needed

[Djalal Harouni]

Signed-off-by: Djalal Harouni <tixxdz at opendz.org>
---
 domain.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/domain.c b/domain.c
index d27cad2..554b4fe 100644
--- a/domain.c
+++ b/domain.c
@@ -183,12 +183,13 @@ struct kdbus_domain *kdbus_domain_unref(struct kdbus_domain *domain)
 	return NULL;
 }
 
-static struct kdbus_domain *kdbus_domain_find(struct kdbus_domain const *parent,
+static struct kdbus_domain *kdbus_domain_find(struct kdbus_domain *parent,
 				      const char *name)
 {
 	struct kdbus_domain *domain = NULL;
 	struct kdbus_domain *n;
 
+	mutex_lock(&parent->lock);
 	list_for_each_entry(n, &parent->domain_list, domain_entry) {
 		if (strcmp(n->name, name))
 			continue;
@@ -196,6 +197,7 @@ static struct kdbus_domain *kdbus_domain_find(struct kdbus_domain const *parent,
 		domain = kdbus_domain_ref(n);
 		break;
 	}
+	mutex_unlock(&parent->lock);
 
 	return domain;
 }
@@ -288,9 +290,6 @@ int kdbus_domain_new(struct kdbus_domain *parent, const char *name,
 	atomic64_set(&d->msg_seq_last, 0);
 	idr_init(&d->user_idr);
 
-	if (parent)
-		mutex_lock(&parent->lock);
-
 	mutex_lock(&kdbus_subsys_lock);
 
 	/* compose name and path of base directory in /dev */
@@ -340,21 +339,19 @@ int kdbus_domain_new(struct kdbus_domain *parent, const char *name,
 
 	/* link into parent domain */
 	if (parent) {
+		mutex_lock(&parent->lock);
 		d->parent = kdbus_domain_ref(parent);
 		list_add_tail(&d->domain_entry, &parent->domain_list);
+		mutex_unlock(&parent->lock);
 	}
 
 	mutex_unlock(&kdbus_subsys_lock);
-	if (parent)
-		mutex_unlock(&parent->lock);
 
 	*domain = d;
 	return 0;
 
 exit_unlock:
 	mutex_unlock(&kdbus_subsys_lock);
-	if (parent)
-		mutex_unlock(&parent->lock);
 	kdbus_domain_unref(d);
 	return ret;
 }
-- 
1.8.5.3