linux-kernel - Re: [PATCH] PCI: Do not enable INTx in pci_reenable

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Date:	Fri, 14 Mar 2014 17:30:31 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Chris Cheng <chris.cheng@...ustcorp.com>,
	Jamie Chen <jamie.chen@...el.com>,
	Andreas Noever <andreas.noever@...il.com>
Subject: Re: [PATCH] PCI: Do not enable INTx in pci_reenable_device()

On Tue, Mar 11, 2014 at 10:48 AM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
> Andreas reported that after 1f42db786b14 ("PCI: Enable INTx if BIOS left
> them disabled"), pciehp surprise removal stopped working.
>
> This happens because pci_reenable_device() on the hotplug bridge (used in
> the pciehp_configure_device() path) clears the Interrupt Disable bit, which
> apparently breaks the bridge's MSI hotplug event reporting.
>
> Previously we cleared the Interrupt Disable bit in do_pci_enable_device(),
> which is used by both pci_enable_device() and pci_reenable_device().  But
> we use pci_reenable_device() after the driver may have enabled MSI or
> MSI-X, and we *set* Interrupt Disable as part of enabling MSI/MSI-X.
>
> This patch clears Interrupt Disable only when MSI/MSI-X has not been
> enabled.
>
> Fixes: 1f42db786b14 PCI: Enable INTx if BIOS left them disabled
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=71691
> Reported-and-tested-by: Andreas Noever <andreas.noever@...il.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> CC: stable@...r.kernel.org
> CC: Sarah Sharp <sarah.a.sharp@...ux.intel.com>
> ---
>  drivers/pci/pci.c |    3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 8dc3e701ec57..79fc89c6c3f3 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1192,6 +1192,9 @@ static int do_pci_enable_device(struct pci_dev *dev, int bars)
>                 return err;
>         pci_fixup_device(pci_fixup_enable, dev);
>
> +       if (dev->msi_enabled || dev->msix_enabled)
> +               return 0;
> +
>         pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
>         if (pin) {
>                 pci_read_config_word(dev, PCI_COMMAND, &cmd);

looks ugly.

We really should move out those irq handling out of pci_enable_device.

Yinghai
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