Patchwork rtc: rtc-hid-sensor-time: fix possible bug on driver_remove

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Submitter Alexander Holler
Date June 4, 2013, 9:38 a.m.
Message ID <1370338722-3646-1-git-send-email-holler@ahsoftware.de>
Download mbox | patch
Permalink /patch/248517/
State New
Headers show

Comments

Alexander Holler - June 4, 2013, 9:38 a.m.
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(-)
Alexander Holler - June 8, 2013, 8:56 a.m.
Hello,

sorry to bother again. I've now had the time to play with the new 
hctosys I proposed patches for and rtc-hid-sensor-time.

If the new hctosys mechanism will end up in the kernel, the following 
patches I've recently send and which already got merged to -mm won't 
work anymore and should disappear:

[PATCH 3/4] rtc: rtc-hid-sensor-time: add option hctosys to set time at boot
[PATCH 4/4] rtc: rtc-hid-sensor-time: add support for milliseconds
[PATCH] rtc: rtc-hid-sensor-time: fix possible bug on driver_remove


The other two patches


[PATCH 1/4] rtc: rtc-hid-sensor-time: allow full years (16bit) in HID 
reports
[PATCH 2/4] rtc: rtc-hid-sensor-time: allow 16 and 32 bit values for all 
attributes.

which got merged too are still fine.


I don't know if I should send reverts for those 3 patches, or ...

I've already have a patch which would be needed if the new hctosys would 
be used, but I will delay sending them until we figured out if and how 
that new hctosys will become real. But you might already revert or 
delete the above 3 patches in your tree.


That silly looking driver rtc-hid-sensor-time is really an endless story. :/

Besides writing the driver and an example firmware implementation I had 
to make patches for iio, hid-sensor-hub and hid, and now for timekeeping 
and rtc. All for nothing but the fun having to convince maintainers of 
all sorts and bothering them. ;)


And the todo-list still contains some stuff:

- rtc-hid-sensor-time still does not get loaded automatically if a 
matching hid-sensor-hub appears to the system. That needs changes to hid 
and/or hid-sensor-hub. Problem is that I don't have a real hid sensor 
hub and I don't know why the people which do produce such products and 
have written hid-sensor-hub didn't have implemented a way to do such. Or 
I've just missed something.

- Have to redo millisecond support.

- ntp functionality (e.g. module parameter adjtime) to make it possible 
to use a hardware clock with support for milliseconds to turn the system 
clock to a stratum 1 clock.

- and last but not least I hope the standard for those HID sensors will 
become a standardized way to set the time. I still wouldn't like it if I 
had to "invent" something myself (easy, but it would be linux-specific 
and "invented" by some fool like me who just wrote it's own firmware 
without having any knowledge about some real hid-sensor products ;) ), 
but ...

Regards,

Alexander Holler

Patch

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);