linux-kernel - [PATCH 1/3] driver core: Add device_link

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Message-ID: <1530800748-7300-2-git-send-email-p.paillet@st.com>
Date:   Thu, 5 Jul 2018 14:25:56 +0000
From:   Pascal PAILLET-LME <p.paillet@...com>
To:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "benjamin.gaignard@...aro.org" <benjamin.gaignard@...aro.org>
CC:     Pascal PAILLET-LME <p.paillet@...com>
Subject: [PATCH 1/3] driver core: Add device_link_remove function

From: pascal paillet <p.paillet@...com>

Device_link_remove uses the same arguments than device_link_add. The Goal
is to avoid storing the link pointer.

Signed-off-by: pascal paillet <p.paillet@...com>
---
 drivers/base/core.c    | 30 ++++++++++++++++++++++++++++++
 include/linux/device.h |  1 +
 2 files changed, 31 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 36622b5..3b380b1 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -365,6 +365,36 @@ void device_link_del(struct device_link *link)
 }
 EXPORT_SYMBOL_GPL(device_link_del);
 
+/**
+ * device_link_remove - remove a link between two devices.
+ * @consumer: Consumer end of the link.
+ * @supplier: Supplier end of the link.
+ *
+ * The caller must ensure proper synchronization of this function with runtime
+ * PM.
+ */
+void device_link_remove(void *consumer, struct device *supplier)
+{
+	struct device_link *link;
+
+	if (WARN_ON(consumer == supplier))
+		return;
+
+	device_links_write_lock();
+	device_pm_lock();
+
+	list_for_each_entry(link, &supplier->links.consumers, s_node) {
+		if (link->consumer == consumer) {
+			kref_put(&link->kref, __device_link_del);
+			break;
+		}
+	}
+
+	device_pm_unlock();
+	device_links_write_unlock();
+}
+EXPORT_SYMBOL_GPL(device_link_remove);
+
 static void device_links_missing_supplier(struct device *dev)
 {
 	struct device_link *link;
diff --git a/include/linux/device.h b/include/linux/device.h
index 055a69d..9c1c3b1 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -1316,6 +1316,7 @@ extern void devm_device_remove_group(struct device *dev,
 struct device_link *device_link_add(struct device *consumer,
 				    struct device *supplier, u32 flags);
 void device_link_del(struct device_link *link);
+void device_link_remove(void *consumer, struct device *supplier);
 
 #ifdef CONFIG_PRINTK
 
-- 
1.9.1