LKML Archive on
help / color / mirror / Atom feed
From: "Kristian Høgsberg" <>
To: Greg KH <>
Cc: Pete Zaitcev <>,
Subject: Re: Juju
Date: Fri, 26 Jan 2007 14:51:26 -0500	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Greg KH wrote:
> On Thu, Jan 25, 2007 at 03:38:24PM -0800, Pete Zaitcev wrote:
>> On Thu, 25 Jan 2007 16:18:35 -0500, Kristian H??gsberg <> wrote:
>>>> I see that ORBs are always allocated with a call (like SKB) and not
>>>> embedded into drivers (like URBs). It's great, keep it up. Also,
>>>> never allow drivers to pass DMA-mapped buffers into fw_send_request
>>>> and friends. We made both of these mistakes in USB, and it hurts.
>>> Oh, the ORBs are SBP-2 specific data structures, struct fw_transaction is 
>>> probably what corresponds to USB URBs.  This struct is defined in 
>>> fw-transaction.h and is available for embedding into other structs, such as 
>>> struct sbp2_orb in fw-sbp2.  Is that what you're suggesting against, and what 
>>> are the problems with this approach?
>> Fortunately we do not care about out-of-tree drivers, which are most
>> affected, you may even call it a feature ^_^. My main problem is,
>> we can't refcount URBs, so usbmon can't tap them and must copy.
> urbs are reference counted, it's just that not all drivers who create
> them use them that way :(
> Perhaps you can inforce this in the new codebase...

It's a small change to make the fw_transaction struct opaque and ref-counted, 
and it's definitely still doable.  But the nice thing about embedding the 
struct is that you have one memory allocation failure path less to worry 
about.  And I haven't yet, and don't expect to see a use case that will need 
ref-counted struct fw_transaction, the ownership is always clearly defined. 
But I can go either way on this and if there is a good reason to ref count 
them it's a pretty small change.


  reply	other threads:[~2007-01-26 19:57 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-25  6:37 Juju Pete Zaitcev
2007-01-25 17:13 ` Juju Stefan Richter
2007-01-25 21:18 ` Juju Kristian Høgsberg
2007-01-25 23:38   ` Juju Pete Zaitcev
2007-01-26  2:35     ` Juju Stefan Richter
2007-01-26  4:01       ` Juju Kristian Høgsberg
2007-01-26 11:30         ` Juju Stefan Richter
2007-01-26  4:47       ` Juju Pete Zaitcev
2007-01-26 10:53         ` Juju Stefan Richter
2007-01-26  6:47     ` Juju Greg KH
2007-01-26 19:51       ` Kristian Høgsberg [this message]
2007-01-29  0:13   ` Juju Pete Zaitcev
2007-01-29 19:53     ` Juju Kristian Høgsberg
2007-01-29 20:22       ` Juju Pete Zaitcev

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \
    --subject='Re: Juju' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).