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Message-ID: <59ad55d30803030937h7e8b6487s134aec2d87e00c62@mail.gmail.com>
Date: Mon, 3 Mar 2008 12:37:29 -0500
From: "=?UTF-8?Q?Kristian_H=C3=B8gsberg?=" <krh@bitplanet.net>
To: "Stefan Richter" <stefanr@s5r6.in-berlin.de>
Subject: Re: [PATCH 2/5] firewire: fix crash in automatic module unloading
Cc: linux1394-devel@lists.sourceforge.net, "Jarod Wilson" <jwilson@redhat.com>,
       linux-kernel@vger.kernel.org
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On Mon, Mar 3, 2008 at 12:16 PM, Stefan Richter<stefanr@s5r6.in-berlin.de> wrote:> Kristian Høgsberg wrote:>  > I would want to use a kref and a completion for tracking this though>  > instead of the atomic.  Just use kref_get() instead of incrementing>  > the atomic and use kref_put() instead of decrementing it.  The release>  > function for kref_put() should complete the completion struct and>  > instead of the busy loop in fw_core_remove_card() we just wait for the>  > completion.>>  Sounds like the way to go.  Since I already passed that patch upwards, I>  will do an incremental rework.  (But perhaps not before spending some>  time on ticket number 9617 at bugzilla.kernel.org's...)>>>  > And I'm not sure I agree that it's a device_count, it>  > really just is a ref-count.  The core should also hold a reference to>  > the card and release it in fw_core_remove_card(), just before waiting>  > on the completion.>>  Right; we just shouldn't mix fw-ohci's refcounting (which isn't really>  needed since the lifetime rules for the card are as simple as they can>  get for fw-ohci) and fw-core's refcounting.
Yup, we should keep the fw-ohci side of things simple.  And they stillare: it calls add_card() to add a new card at which point the corestarts using the card.  On removal, it calls remove_card() and whenthat returns the core no knows or cares about the card and fw-ohci.cis free to tear it down however it wants.  When I mention that thecore should hold a ref-count, it's really just that somebody needs toown the initial ref-count and make sure it's dropped on the removepath.
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