* A request to understand the design decisions why tasklets were changed to workqueues eg. hci_rx_task() to hci_rx_work()
@ 2012-04-17 11:28 Dean Jenkins
2012-04-17 15:09 ` Mat Martineau
0 siblings, 1 reply; 2+ messages in thread
From: Dean Jenkins @ 2012-04-17 11:28 UTC (permalink / raw)
To: linux-bluetooth
Hi,
I am interested to the understand the design decisions for changing
from tasklets to workqueues.
Was there a fundamental flaw that necessitated the change ?
I am asking because I am getting a Bluetooth "scheduling while atomic"
failure on an ARM based 2.6.34 kernel (with some 2.6.37 Bluez
backports). Changing to workqueues would avoid this issue as a
workqueue use process context that can sleep.
Thanks for any info on the design decisions.
Regards,
Dean
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: A request to understand the design decisions why tasklets were changed to workqueues eg. hci_rx_task() to hci_rx_work()
2012-04-17 11:28 A request to understand the design decisions why tasklets were changed to workqueues eg. hci_rx_task() to hci_rx_work() Dean Jenkins
@ 2012-04-17 15:09 ` Mat Martineau
0 siblings, 0 replies; 2+ messages in thread
From: Mat Martineau @ 2012-04-17 15:09 UTC (permalink / raw)
To: Dean Jenkins; +Cc: linux-bluetooth
Dean -
On Tue, 17 Apr 2012, Dean Jenkins wrote:
> Hi,
>
> I am interested to the understand the design decisions for changing
> from tasklets to workqueues.
>
> Was there a fundamental flaw that necessitated the change ?
>
> I am asking because I am getting a Bluetooth "scheduling while atomic"
> failure on an ARM based 2.6.34 kernel (with some 2.6.37 Bluez
> backports). Changing to workqueues would avoid this issue as a
> workqueue use process context that can sleep.
>
> Thanks for any info on the design decisions.
Take a look at http://article.gmane.org/gmane.linux.bluez.kernel/19535
and the thread it is part of. The main motivation was to eliminate
bugs and complexity arising from a mix of tasklet-context and
process-context code. Locking and concurrency problems have become
trickier with the introduction of the management interface, L2CAP
ERTM, and AMP.
There were big changes to the workqueue internals in 2.6.36, I don't
know if that will cause major issues when backporting current code to
2.6.34.
--
Mat Martineau
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
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2012-04-17 11:28 A request to understand the design decisions why tasklets were changed to workqueues eg. hci_rx_task() to hci_rx_work() Dean Jenkins
2012-04-17 15:09 ` Mat Martineau
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