linux-kernel - [PATCH] Bluetooth: Clear suspend tasks on unregister

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Message-Id: <20200826154719.1.I24fb6cc377d03d64d74f83cec748afd12ee33e37@changeid>
Date:   Wed, 26 Aug 2020 15:47:22 -0700
From:   Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
To:     marcel@...tmann.org, linux-bluetooth@...r.kernel.org
Cc:     chromeos-bluetooth-upstreaming@...omium.org,
        Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Johan Hedberg <johan.hedberg@...il.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jakub Kicinski <kuba@...nel.org>,
        Miao-chen Chou <mcchou@...omium.org>
Subject: [PATCH] Bluetooth: Clear suspend tasks on unregister

While unregistering, make sure to clear the suspend tasks before
cancelling the work. If the unregister is called during resume from
suspend, this will unnecessarily add 2s to the resume time otherwise.

Fixes: 4e8c36c3b0d73d (Bluetooth: Fix suspend notifier race)
Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
---
This was discovered with RT8822CE using the btusb driver. This chipset
will reset on resume during system suspend and was unnecessarily adding
2s to every resume. Since we're unregistering anyway, there's no harm in
just clearing the pending events.

 net/bluetooth/hci_core.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 68bfe57b66250f..ed4cb3479433c0 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3442,6 +3442,16 @@ void hci_copy_identity_address(struct hci_dev *hdev, bdaddr_t *bdaddr,
 	}
 }
 
+static void hci_suspend_clear_tasks(struct hci_dev *hdev)
+{
+	int i;
+
+	for (i = 0; i < __SUSPEND_NUM_TASKS; ++i)
+		clear_bit(i, hdev->suspend_tasks);
+
+	wake_up(&hdev->suspend_wait_q);
+}
+
 static int hci_suspend_wait_event(struct hci_dev *hdev)
 {
 #define WAKE_COND                                                              \
@@ -3785,6 +3795,7 @@ void hci_unregister_dev(struct hci_dev *hdev)
 	cancel_work_sync(&hdev->power_on);
 
 	unregister_pm_notifier(&hdev->suspend_notifier);
+	hci_suspend_clear_tasks(hdev);
 	cancel_work_sync(&hdev->suspend_prepare);
 
 	hci_dev_do_close(hdev);
-- 
2.28.0.297.g1956fa8f8d-goog