[PATCH] rtc: rtc-hid-sensor-time: fix possible bug on driver_remove

[Alexander Holler <holler@ahsoftware.de>]

The work we schedule on register deletes himself. Therefor we cannot
use cancel_work_sync() because that calls flush_work() but still uses
the pointer to the (now deleted) work afterwards (for clear_work_data)
which ends up in a bug.
Replacing cancel_work_sync() with flush_work() fixes that.

Signed-off-by: Alexander Holler <holler@ahsoftware.de>
---

 This patch applies on top of PATCH 3/4 or 4/4 of the small series of 4 patches
 for rtc-hid-sensor-time, which was already merged into the -mm tree.

 drivers/rtc/rtc-hid-sensor-time.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/rtc/rtc-hid-sensor-time.c b/drivers/rtc/rtc-hid-sensor-time.c
index 4aca12d..acb2bc2 100644
--- a/drivers/rtc/rtc-hid-sensor-time.c
+++ b/drivers/rtc/rtc-hid-sensor-time.c
@@ -414,9 +414,8 @@ static int hid_time_remove(struct platform_device *pdev)
 	struct hid_time_state *time_state = platform_get_drvdata(pdev);
 
 	if (time_state->workts) {
-		cancel_work_sync(&time_state->workts->work);
-		kfree(time_state->workts);
-		time_state->workts = NULL;
+		flush_work(&time_state->workts->work);
+		BUG_ON(time_state->workts != NULL);
 	}
 	sensor_hub_remove_callback(hsdev, HID_USAGE_SENSOR_TIME);
 
-- 
1.8.1.5