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Date: Mon, 15 Jul 2019 10:37:01 -0400
From: "Joel Fernandes (Google)" <joel@...lfernandes.org>
To: linux-kernel@...r.kernel.org
Cc: "Joel Fernandes (Google)" <joel@...lfernandes.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Borislav Petkov <bp@...en8.de>,
	c0d1n61at3@...il.com,
	"David S. Miller" <davem@...emloft.net>,
	edumazet@...gle.com,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Ingo Molnar <mingo@...hat.com>,
	Jonathan Corbet <corbet@....net>,
	Josh Triplett <josh@...htriplett.org>,
	keescook@...omium.org,
	kernel-hardening@...ts.openwall.com,
	kernel-team@...roid.com,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Len Brown <lenb@...nel.org>,
	linux-acpi@...r.kernel.org,
	linux-doc@...r.kernel.org,
	linux-pci@...r.kernel.org,
	linux-pm@...r.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	neilb@...e.com,
	netdev@...r.kernel.org,
	Oleg Nesterov <oleg@...hat.com>,
	"Paul E. McKenney" <paulmck@...ux.ibm.com>,
	Pavel Machek <pavel@....cz>,
	peterz@...radead.org,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
	rcu@...r.kernel.org,
	Steven Rostedt <rostedt@...dmis.org>,
	Tejun Heo <tj@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	will@...nel.org,
	x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT))
Subject: [PATCH 5/9] driver/core: Convert to use built-in RCU list checking (v1)

list_for_each_entry_rcu has built-in RCU and lock checking. Make use of
it in driver core.

Acked-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
---
 drivers/base/base.h          |  1 +
 drivers/base/core.c          | 10 ++++++++++
 drivers/base/power/runtime.c | 15 ++++++++++-----
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/drivers/base/base.h b/drivers/base/base.h
index b405436ee28e..0d32544b6f91 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -165,6 +165,7 @@ static inline int devtmpfs_init(void) { return 0; }
 /* Device links support */
 extern int device_links_read_lock(void);
 extern void device_links_read_unlock(int idx);
+extern int device_links_read_lock_held(void);
 extern int device_links_check_suppliers(struct device *dev);
 extern void device_links_driver_bound(struct device *dev);
 extern void device_links_driver_cleanup(struct device *dev);
diff --git a/drivers/base/core.c b/drivers/base/core.c
index da84a73f2ba6..85e82f38717f 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -68,6 +68,11 @@ void device_links_read_unlock(int idx)
 {
 	srcu_read_unlock(&device_links_srcu, idx);
 }
+
+int device_links_read_lock_held(void)
+{
+	return srcu_read_lock_held(&device_links_srcu);
+}
 #else /* !CONFIG_SRCU */
 static DECLARE_RWSEM(device_links_lock);
 
@@ -91,6 +96,11 @@ void device_links_read_unlock(int not_used)
 {
 	up_read(&device_links_lock);
 }
+
+int device_links_read_lock_held(void)
+{
+	return lock_is_held(&device_links_lock);
+}
 #endif /* !CONFIG_SRCU */
 
 /**
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 952a1e7057c7..7a10e8379a70 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -287,7 +287,8 @@ static int rpm_get_suppliers(struct device *dev)
 {
 	struct device_link *link;
 
-	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
+				device_links_read_lock_held()) {
 		int retval;
 
 		if (!(link->flags & DL_FLAG_PM_RUNTIME) ||
@@ -309,7 +310,8 @@ static void rpm_put_suppliers(struct device *dev)
 {
 	struct device_link *link;
 
-	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
+				device_links_read_lock_held()) {
 		if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND)
 			continue;
 
@@ -1640,7 +1642,8 @@ void pm_runtime_clean_up_links(struct device *dev)
 
 	idx = device_links_read_lock();
 
-	list_for_each_entry_rcu(link, &dev->links.consumers, s_node) {
+	list_for_each_entry_rcu(link, &dev->links.consumers, s_node,
+				device_links_read_lock_held()) {
 		if (link->flags & DL_FLAG_STATELESS)
 			continue;
 
@@ -1662,7 +1665,8 @@ void pm_runtime_get_suppliers(struct device *dev)
 
 	idx = device_links_read_lock();
 
-	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
+				device_links_read_lock_held())
 		if (link->flags & DL_FLAG_PM_RUNTIME) {
 			link->supplier_preactivated = true;
 			refcount_inc(&link->rpm_active);
@@ -1683,7 +1687,8 @@ void pm_runtime_put_suppliers(struct device *dev)
 
 	idx = device_links_read_lock();
 
-	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
+				device_links_read_lock_held())
 		if (link->supplier_preactivated) {
 			link->supplier_preactivated = false;
 			if (refcount_dec_not_one(&link->rpm_active))
-- 
2.22.0.510.g264f2c817a-goog

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