linux-kernel - [PATCH 2/2] Bluetooth: Unregister suspend with userchannel

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Date:   Thu,  2 Jun 2022 09:46:50 -0700
From:   Abhishek Pandit-Subedi <abhishekpandit@...gle.com>
To:     linux-bluetooth@...r.kernel.org, marcel@...tmann.org,
        luiz.dentz@...il.com
Cc:     Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Paolo Abeni <pabeni@...hat.com>, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org
Subject: [PATCH 2/2] Bluetooth: Unregister suspend with userchannel

From: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>

When HCI_USERCHANNEL is used, unregister the suspend notifier when
binding and register when releasing. The userchannel socket should be
left alone after open is completed.

Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
---
Currently, the suspend notifier is harmless when used since no traffic
is actually passed to controller with HCI_USERCHANNEL. When I suspend,
all I see is the MGMT Controller Suspended and Controller Resumed
events. However, for correctness, I've opted to unregister the suspend
notifier entirely when using HCI_USERCHANNEL (similar to how the
HCI_QUIRK_NO_SUSPEND_NOTIFIER works).

The alternative to this approach would be to always keep the notifier
registered and exit early in hci_suspend_notifier. Please let me know
which you prefer.

Tested on ChromeOS kernel and compiled with allmodconfig on
bluetooth-next.

 include/net/bluetooth/hci_core.h |  2 ++
 net/bluetooth/hci_core.c         | 33 ++++++++++++++++++++++++--------
 net/bluetooth/hci_sock.c         |  3 +++
 3 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 5a52a2018b56..5b92a9abe141 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -1289,6 +1289,8 @@ void hci_free_dev(struct hci_dev *hdev);
 int hci_register_dev(struct hci_dev *hdev);
 void hci_unregister_dev(struct hci_dev *hdev);
 void hci_release_dev(struct hci_dev *hdev);
+int hci_register_suspend_notifier(struct hci_dev *hdev);
+int hci_unregister_suspend_notifier(struct hci_dev *hdev);
 int hci_suspend_dev(struct hci_dev *hdev);
 int hci_resume_dev(struct hci_dev *hdev);
 int hci_reset_dev(struct hci_dev *hdev);
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 5abb2ca5b129..ab647a63830d 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2639,12 +2639,8 @@ int hci_register_dev(struct hci_dev *hdev)
 	hci_sock_dev_event(hdev, HCI_DEV_REG);
 	hci_dev_hold(hdev);
 
-	if (!test_bit(HCI_QUIRK_NO_SUSPEND_NOTIFIER, &hdev->quirks)) {
-		hdev->suspend_notifier.notifier_call = hci_suspend_notifier;
-		error = register_pm_notifier(&hdev->suspend_notifier);
-		if (error)
-			goto err_wqueue;
-	}
+	if (hci_register_suspend_notifier(hdev))
+		goto err_wqueue;
 
 	queue_work(hdev->req_workqueue, &hdev->power_on);
 
@@ -2677,8 +2673,7 @@ void hci_unregister_dev(struct hci_dev *hdev)
 
 	hci_cmd_sync_clear(hdev);
 
-	if (!test_bit(HCI_QUIRK_NO_SUSPEND_NOTIFIER, &hdev->quirks))
-		unregister_pm_notifier(&hdev->suspend_notifier);
+	hci_unregister_suspend_notifier(hdev);
 
 	msft_unregister(hdev);
 
@@ -2742,6 +2737,28 @@ void hci_release_dev(struct hci_dev *hdev)
 }
 EXPORT_SYMBOL(hci_release_dev);
 
+int hci_register_suspend_notifier(struct hci_dev *hdev)
+{
+	int ret = 0;
+
+	if (!test_bit(HCI_QUIRK_NO_SUSPEND_NOTIFIER, &hdev->quirks)) {
+		hdev->suspend_notifier.notifier_call = hci_suspend_notifier;
+		ret = register_pm_notifier(&hdev->suspend_notifier);
+	}
+
+	return ret;
+}
+
+int hci_unregister_suspend_notifier(struct hci_dev *hdev)
+{
+	int ret = 0;
+
+	if (!test_bit(HCI_QUIRK_NO_SUSPEND_NOTIFIER, &hdev->quirks))
+		ret = unregister_pm_notifier(&hdev->suspend_notifier);
+
+	return ret;
+}
+
 /* Suspend HCI device */
 int hci_suspend_dev(struct hci_dev *hdev)
 {
diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index bd8358b44aa4..0d015d4a8e41 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -887,6 +887,7 @@ static int hci_sock_release(struct socket *sock)
 			 */
 			hci_dev_do_close(hdev);
 			hci_dev_clear_flag(hdev, HCI_USER_CHANNEL);
+			hci_register_suspend_notifier(hdev);
 			mgmt_index_added(hdev);
 		}
 
@@ -1215,6 +1216,7 @@ static int hci_sock_bind(struct socket *sock, struct sockaddr *addr,
 		}
 
 		mgmt_index_removed(hdev);
+		hci_unregister_suspend_notifier(hdev);
 
 		err = hci_dev_open(hdev->id);
 		if (err) {
@@ -1229,6 +1231,7 @@ static int hci_sock_bind(struct socket *sock, struct sockaddr *addr,
 				err = 0;
 			} else {
 				hci_dev_clear_flag(hdev, HCI_USER_CHANNEL);
+				hci_register_suspend_notifier(hdev);
 				mgmt_index_added(hdev);
 				hci_dev_put(hdev);
 				goto done;
-- 
2.36.1.255.ge46751e96f-goog