From: Alan Stern <stern@rowland.harvard.edu>
To: Oliver Neukum <oneukum@suse.com>
Cc: linux-usb@vger.kernel.org
Subject: Re: [RFC]extension of the anchor API
Date: Thu, 25 Mar 2021 14:38:56 -0400 [thread overview]
Message-ID: <20210325183856.GA799855@rowland.harvard.edu> (raw)
In-Reply-To: <5d3852dca69ff194017c806078e996c50ee621be.camel@suse.com>
On Thu, Mar 25, 2021 at 05:04:25PM +0100, Oliver Neukum wrote:
> Am Donnerstag, den 25.03.2021, 11:06 -0400 schrieb Alan Stern:
> > > +:c:func:`usb_submit_anchored_urbs`
> > > +---------------------------------
> > > +
> > > +The URBs contained in anchor are chronologically submitted until
> >
> > "chronologically" is the wrong word. They are submitted in the order
> > of the anchor's list, which is the same as the order that an iterator
> > would use.
>
> OK. "In the same sequence as they were anchored" ?
Hmmm. What happens if you submit an anchor's worth of URBs, but then
you kill them in the reverse order (which is how you would normally want
to cancel a bunch of URBs)? Since each URB gets moved to the end of the
anchor's list when it completes, after they are all killed the list will
be reversed. So the next time you submit the anchor, the order of URBs
will be backward. If some of the URBs completed before they were
killed, the order will be mixed up.
Of course, if you never use the URBs on an anchor after killing it, this
doesn't matter.
Alan Stern
next prev parent reply other threads:[~2021-03-25 18:39 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-25 11:03 [RFC]extension of the anchor API Oliver Neukum
2021-03-25 15:06 ` Alan Stern
2021-03-25 16:04 ` Oliver Neukum
2021-03-25 18:38 ` Alan Stern [this message]
2021-04-08 9:23 ` Oliver Neukum
2021-04-08 15:07 ` Alan Stern
2021-04-12 9:58 ` Oliver Neukum
2021-04-12 15:06 ` Alan Stern
2021-04-14 8:12 ` Oliver Neukum
2021-04-14 14:56 ` Alan Stern
2021-04-15 11:23 ` Oliver Neukum
2021-04-15 15:18 ` Alan Stern
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