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From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] PNP: Unbind drivers if the new driver matches _HID rather than _CID
Date: Tue, 25 Sep 2012 20:22:11 +0100	[thread overview]
Message-ID: <20120925192211.GA24750@srcf.ucam.org> (raw)
In-Reply-To: <CAErSpo7giiZEnXkRY+QnhAV_2EGwdnju7S1-futjnKBjr7sY-A@mail.gmail.com>

On Tue, Sep 25, 2012 at 01:04:25PM -0600, Bjorn Helgaas wrote:
> On Tue, Sep 25, 2012 at 7:25 AM, Matthew Garrett <mjg@redhat.com> wrote:

> Do you know of any scenarios besides this IPMI one where there's the
> possibility of two drivers matching the same device?  If so, does the
> detach/attach process work reasonably?  My worry is that drivers don't
> normally give up devices, so the detach path is not well exercised.
> And I don't know what happens to any users of the device during the
> switch.  For example, if something was using a TPM and we replaced the
> driver, what does that look like to the user?

Yeah, this could definitely happen with TPM - tpm_infinion could 
displace tpm_tis. This actually flags up something kind of obviously 
broken in the TPM code, since tpm_infineon comes *after* tpm_tis in the 
link order despite being more specific. Winning. It looks like there's a 
valid tpm_release function, but I'll find an infineon machine and figure 
out whether it actually works or not.

-- 
Matthew Garrett | mjg59@srcf.ucam.org

  reply	other threads:[~2012-09-25 19:22 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-25 13:25 [PATCH 1/2] PNP: Add a release method to system resource driver Matthew Garrett
2012-09-25 13:25 ` [PATCH 2/2] PNP: Unbind drivers if the new driver matches _HID rather than _CID Matthew Garrett
2012-09-25 19:04   ` Bjorn Helgaas
2012-09-25 19:22     ` Matthew Garrett [this message]
2012-09-25 16:27 ` [PATCH 1/2] PNP: Add a release method to system resource driver Bjorn Helgaas

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