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SubjectRe: [PATCH 5/9] usb: don't use PREPARE_DELAYED_WORK
On Thu, Feb 20, 2014 at 03:44:27PM -0500, Tejun Heo wrote:
> PREPARE_[DELAYED_]WORK() are being phased out. They have few users
> and a nasty surprise in terms of reentrancy guarantee as workqueue
> considers work items to be different if they don't have the same work
> function.
>
> usb_hub->init_work is multiplexed with multiple work functions.
> Introduce hub_init_workfn() which invokes usb_hub->init_workfn and
> always use it as the work function and update the users to set the
> ->init_workfn field instead of overriding the work function using
> PREPARE_DELAYED_WORK().
>
> It looks like that the work items are never queued while in-flight, so
> simply using INIT_DELAYED_WORK() before each queueing could be enough.
> This patch performs equivalent conversion just in case but we probably
> wanna clean it up later if that's the case.

I think it should be fine to use INIT_DELAYED_WORK(), but Alan would
know best. Alan?

>
> It would probably be best to route this with other related updates
> through the workqueue tree.
>
> Lightly tested.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-usb@vger.kernel.org

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

> ---
> drivers/usb/core/hub.c | 13 ++++++++++---
> drivers/usb/core/hub.h | 1 +
> 2 files changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 64ea219..2bc61c0 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -1040,7 +1040,7 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
> */
> if (type == HUB_INIT) {
> delay = hub_power_on(hub, false);
> - PREPARE_DELAYED_WORK(&hub->init_work, hub_init_func2);
> + hub->init_workfn = hub_init_func2;
> schedule_delayed_work(&hub->init_work,
> msecs_to_jiffies(delay));
>
> @@ -1194,7 +1194,7 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
>
> /* Don't do a long sleep inside a workqueue routine */
> if (type == HUB_INIT2) {
> - PREPARE_DELAYED_WORK(&hub->init_work, hub_init_func3);
> + hub->init_workfn = hub_init_func3;
> schedule_delayed_work(&hub->init_work,
> msecs_to_jiffies(delay));
> return; /* Continues at init3: below */
> @@ -1634,6 +1634,13 @@ static void hub_disconnect(struct usb_interface *intf)
> kref_put(&hub->kref, hub_release);
> }
>
> +static void hub_init_workfn(struct work_struct *work)
> +{
> + struct usb_hub *hub = container_of(to_delayed_work(work),
> + struct usb_hub, init_work);
> + hub->init_workfn(work);
> +}
> +
> static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
> {
> struct usb_host_interface *desc;
> @@ -1728,7 +1735,7 @@ descriptor_error:
> hub->intfdev = &intf->dev;
> hub->hdev = hdev;
> INIT_DELAYED_WORK(&hub->leds, led_work);
> - INIT_DELAYED_WORK(&hub->init_work, NULL);
> + INIT_DELAYED_WORK(&hub->init_work, hub_init_workfn);
> usb_get_intf(intf);
>
> usb_set_intfdata (intf, hub);
> diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
> index df629a3..ef81463 100644
> --- a/drivers/usb/core/hub.h
> +++ b/drivers/usb/core/hub.h
> @@ -72,6 +72,7 @@ struct usb_hub {
> unsigned has_indicators:1;
> u8 indicator[USB_MAXCHILDREN];
> struct delayed_work leds;
> + work_func_t init_workfn;
> struct delayed_work init_work;
> struct usb_port **ports;
> };
> --
> 1.8.5.3


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