[PATCH v7] Bluetooth: hci_qca: Fix missing wakeup during SSR memdump handling

[Shuai Zhang]

When a Bluetooth controller encounters a coredump, it triggers the
Subsystem Restart (SSR) mechanism. The controller first reports the
coredump data and, once the upload is complete, sends a hw_error
event. The host relies on this event to proceed with subsequent
recovery actions.

If the host has not finished processing the coredump data when the
hw_error event is received, it waits until either the processing is
complete or the 8-second timeout expires before handling the event.

The current implementation clears QCA_MEMDUMP_COLLECTION using
clear_bit(), which does not wake up waiters sleeping in
wait_on_bit_timeout(). As a result, the waiting thread may remain
blocked until the timeout expires even if the coredump collection
has already completed.

Fix this by clearing QCA_MEMDUMP_COLLECTION with
clear_and_wake_up_bit(), which also wakes up the waiting thread and
allows the hw_error handling to proceed immediately.

Test case:
- Trigger a controller coredump using:
    hcitool cmd 0x3f 0c 26
- Tested on QCA6390.
- Capture HCI logs using btmon.
- Verify that the delay between receiving the hw_error event and
  initiating the power-off sequence is reduced compared to the
  timeout-based behavior.

Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
Reviewed-by: Paul Menzel <pmenzel@xxxxxxxxxxxxx>
Signed-off-by: Shuai Zhang <shuai.zhang@xxxxxxxxxxxxxxxx>
---
Changes v7:
- Reflow commit message and clarify wording.
- Mention the timeout value and affected controller.
- Add Reviewed-by from Paul Menzel.
- Link to v6
  https://lore.kernel.org/all/20260410085202.4128000-1-shuai.zhang@xxxxxxxxxxxxxxxx/

Changes v6:
- Replace wake_up_bit with clear_and_wake_up_bit 
- Link to v5
  https://lore.kernel.org/all/20260409112233.3326467-1-shuai.zhang@xxxxxxxxxxxxxxxx/

Changes v5:
- Replace clear_and_wake_up_bit with wake_up_bit
- Link to v4
  https://lore.kernel.org/all/20260327083258.1398450-1-shuai.zhang@xxxxxxxxxxxxxxxx/

Changes v4:
- add Acked-by signoff
- Link to v3
  https://lore.kernel.org/all/20251107033924.3707495-1-quic_shuaz@xxxxxxxxxxx/

Changes v3:
- add Fixes tag
- Link to v2
  https://lore.kernel.org/all/20251106140103.1406081-1-quic_shuaz@xxxxxxxxxxx/

Changes v2:
- Split timeout conversion into a separate patch.
- Clarified commit messages and added test case description.
- Link to v1
  https://lore.kernel.org/all/20251104112601.2670019-1-quic_shuaz@xxxxxxxxxxx/
---
 drivers/bluetooth/hci_qca.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index c17a462ae..228a754a9 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -1108,7 +1108,7 @@ static void qca_controller_memdump(struct work_struct *work)
 				qca->qca_memdump = NULL;
 				qca->memdump_state = QCA_MEMDUMP_COLLECTED;
 				cancel_delayed_work(&qca->ctrl_memdump_timeout);
-				clear_bit(QCA_MEMDUMP_COLLECTION, &qca->flags);
+				clear_and_wake_up_bit(QCA_MEMDUMP_COLLECTION, &qca->flags);
 				clear_bit(QCA_IBS_DISABLED, &qca->flags);
 				mutex_unlock(&qca->hci_memdump_lock);
 				return;
@@ -1186,7 +1186,7 @@ static void qca_controller_memdump(struct work_struct *work)
 			kfree(qca->qca_memdump);
 			qca->qca_memdump = NULL;
 			qca->memdump_state = QCA_MEMDUMP_COLLECTED;
-			clear_bit(QCA_MEMDUMP_COLLECTION, &qca->flags);
+			clear_and_wake_up_bit(QCA_MEMDUMP_COLLECTION, &qca->flags);
 		}
 
 		mutex_unlock(&qca->hci_memdump_lock);
-- 
2.34.1