linux-kernel - Re: [PATCH 2/4] usb: hub: remove obsolete while cycle in hub

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Message-ID: <Pine.LNX.4.44L0.1409171159510.1579-100000@iolanthe.rowland.org>
Date:	Wed, 17 Sep 2014 12:01:46 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Petr MlÃ¡dek <pmladek@...e.cz>
cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Tejun Heo <tj@...nel.org>,
	Joe Lawrence <joe.lawrence@...atus.com>,
	Jiri Kosina <jkosina@...e.cz>, <linux-usb@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/4] usb: hub: remove obsolete while cycle in hub_event()

On Wed, 17 Sep 2014, Petr [iso-8859-1] Mládek wrote:

> On Fri 12-09-14 10:23:26, Alan Stern wrote:
> > On Fri, 12 Sep 2014, Petr Mladek wrote:
> > 
> > > The USB hub events are proceed by workqueue instead of kthread now.
> > > The result is that hub_event() function processes only one event.
> > > The while cycle was not removed earlier to show the real changes when
> > > switching to the workqueue.
> > > 
> > > This patch also consolidates the goto targets and rename them from "loop*"
> > > to "out*".
> > > 
> > > When touching the code, it fixes also formatting of dev_err() and dev_dbg()
> > > calls to make checkpatch.pl happy :-)
> > 
> > Although the reason given in the description above is not really
> > accurate, removing the loop in hub_events is a reasonable thing to do.  
> > That loop doesn't serve any purpose as far as I can see.
> 
> IMHO, the while cycle was needed when hub_events() was used in
> khubd thread. More events could had been added to the list before
> the thread was scheduled.

There's nothing wrong with that.  The thread would get around to 
executing the extra events in due course.

> Therefore I think that the above description makes sense.
> 
> And this is why I did not change the order of the patches in v2 of the patch
> set. I sent all patches again because this one and the 3rd one needed
> refresh.

The patch is getting close.  There are still a couple of problems 
remaining.  I'll go into more detail in another email.

Alan Stern

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