linux-kernel - [PATCH v2 5/9] usb: don't use PREPARE_DELAYED

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Date:	Sat, 22 Feb 2014 09:59:59 -0500
From:	Tejun Heo <tj@...nel.org>
To:	laijs@...fujitsu.com
Cc:	linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, Alan Stern <stern@...land.harvard.edu>
Subject: [PATCH v2 5/9] usb: don't use PREPARE_DELAYED_WORK

Hello,

If this is actually safe, let's do it from the get-go.

Thanks!
------- 8< -------
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;
however, the work item is never queued while in-flight, so we can
simply use INIT_DELAYED_WORK() before each queueing.

It would probably be best to route this with other related updates
through the workqueue tree.

Lightly tested.

v2: Greg and Alan confirm that the work item is never queued while
    in-flight.  Simply use INIT_DELAYED_WORK().

Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Alan Stern <stern@...land.harvard.edu>
Cc: linux-usb@...r.kernel.org
---
 drivers/usb/core/hub.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1040,7 +1040,7 @@ static void hub_activate(struct usb_hub
 		 */
 		if (type == HUB_INIT) {
 			delay = hub_power_on(hub, false);
-			PREPARE_DELAYED_WORK(&hub->init_work, hub_init_func2);
+			INIT_DELAYED_WORK(&hub->init_work, hub_init_func2);
 			schedule_delayed_work(&hub->init_work,
 					msecs_to_jiffies(delay));
 
@@ -1194,7 +1194,7 @@ static void hub_activate(struct usb_hub
 
 		/* Don't do a long sleep inside a workqueue routine */
 		if (type == HUB_INIT2) {
-			PREPARE_DELAYED_WORK(&hub->init_work, hub_init_func3);
+			INIT_DELAYED_WORK(&hub->init_work, hub_init_func3);
 			schedule_delayed_work(&hub->init_work,
 					msecs_to_jiffies(delay));
 			return;		/* Continues at init3: below */
--
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