[PATCH v2] Bluetooth: btmtk: remove redundant memory barrier with helper

[PATCH v2] Bluetooth: btmtk: remove redundant memory barrier with helper

[Arnaud Bonnet]

The test_and_clear_bit() call works as a full memory barrier, thus it is
not required to emit a barrier using smp_mb__after_atomic() before
wake_up_bit().

Replace the whole sequences with test_and_clear_wake_up_bit(), which was
introduced later in commit 52d633def56c ("sched: Add
test_and_clear_wake_up_bit() and atomic_dec_and_wake_up()") as a wrapper
for the correct sequence.

Signed-off-by: Arnaud Bonnet <abo@medichon.fr>
---
Tested by building and manually checking generated assembly on x86, arm64
and riscv64.

Changes since v1:
	* perform the cleanup in btmtksdio.c and btmtkuart.c as well

 drivers/bluetooth/btmtk.c     | 8 +-------
 drivers/bluetooth/btmtksdio.c | 8 ++------
 drivers/bluetooth/btmtkuart.c | 8 ++------
 3 files changed, 5 insertions(+), 19 deletions(-)

diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
index 75483d8230e1..a620e24b6c17 100644
--- a/drivers/bluetooth/btmtk.c
+++ b/drivers/bluetooth/btmtk.c
@@ -607,13 +607,7 @@ static void btmtk_usb_wmt_recv(struct urb *urb)
 			return;
 		}
 
-		if (test_and_clear_bit(BTMTK_TX_WAIT_VND_EVT,
-				       &data->flags)) {
-			/* Barrier to sync with other CPUs */
-			smp_mb__after_atomic();
-			wake_up_bit(&data->flags,
-				    BTMTK_TX_WAIT_VND_EVT);
-		}
+		test_and_clear_wake_up_bit(BTMTK_TX_WAIT_VND_EVT, &data->flags);
 		kfree(urb->setup_packet);
 		return;
 	} else if (urb->status == -ENOENT) {
diff --git a/drivers/bluetooth/btmtksdio.c b/drivers/bluetooth/btmtksdio.c
index b9563df72983..b6e16716b169 100644
--- a/drivers/bluetooth/btmtksdio.c
+++ b/drivers/bluetooth/btmtksdio.c
@@ -442,12 +442,8 @@ static int btmtksdio_recv_event(struct hci_dev *hdev, struct sk_buff *skb)
 		goto err_free_skb;
 
 	if (evt == HCI_EV_WMT) {
-		if (test_and_clear_bit(BTMTKSDIO_TX_WAIT_VND_EVT,
-				       &bdev->tx_state)) {
-			/* Barrier to sync with other CPUs */
-			smp_mb__after_atomic();
-			wake_up_bit(&bdev->tx_state, BTMTKSDIO_TX_WAIT_VND_EVT);
-		}
+		test_and_clear_wake_up_bit(BTMTKSDIO_TX_WAIT_VND_EVT,
+				       &bdev->tx_state);
 	}
 
 	return 0;
diff --git a/drivers/bluetooth/btmtkuart.c b/drivers/bluetooth/btmtkuart.c
index 4af6fbbbd302..744a87acaadc 100644
--- a/drivers/bluetooth/btmtkuart.c
+++ b/drivers/bluetooth/btmtkuart.c
@@ -229,12 +229,8 @@ static int btmtkuart_recv_event(struct hci_dev *hdev, struct sk_buff *skb)
 		goto err_free_skb;
 
 	if (hdr->evt == HCI_EV_WMT) {
-		if (test_and_clear_bit(BTMTKUART_TX_WAIT_VND_EVT,
-				       &bdev->tx_state)) {
-			/* Barrier to sync with other CPUs */
-			smp_mb__after_atomic();
-			wake_up_bit(&bdev->tx_state, BTMTKUART_TX_WAIT_VND_EVT);
-		}
+		test_and_clear_wake_up_bit(BTMTKUART_TX_WAIT_VND_EVT,
+				       &bdev->tx_state);
 	}
 
 	return 0;
-- 
2.53.0

Re: [PATCH v2] Bluetooth: btmtk: remove redundant memory barrier with helper

[patchwork-bot+bluetooth]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Fri, 23 Oct 2026 11:36:45 +0200 you wrote:
> The test_and_clear_bit() call works as a full memory barrier, thus it is
> not required to emit a barrier using smp_mb__after_atomic() before
> wake_up_bit().
> 
> Replace the whole sequences with test_and_clear_wake_up_bit(), which was
> introduced later in commit 52d633def56c ("sched: Add
> test_and_clear_wake_up_bit() and atomic_dec_and_wake_up()") as a wrapper
> for the correct sequence.
> 
> [...]

Here is the summary with links:
  - [v2] Bluetooth: btmtk: remove redundant memory barrier with helper
    https://git.kernel.org/bluetooth/bluetooth-next/c/ebb8ee296578

You are awesome, thank you!
-- 
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