linux-kernel - [PATCH] PCI, x86: fix default vga ref

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Date:	Fri, 14 Sep 2012 17:48:40 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	Yinghai Lu <yinghai@...nel.org>, x86@...nel.org
Subject: [PATCH] PCI, x86: fix default vga ref_count

when __ARCH_HAS_VGA_DEFAULT_DEVICE is not defined, aka EFIFB is not used,

for static path, vga_default setting is through vga_arbiter_add_pci_device.
and for x86 pci_fixup_video, will skip that.
because subsys_initcall(vga_arb_device_init) come first to call vga_arbiter_add_pci_device.

for hotplug path, even vga_arbiter_add_pci_device is called via notifier, but it
will check VGA_RSRC_LEGACY_MASK that is not set for hotplug path.
So x86 pci_fixup_video will take over to call vga_set_default_device().

We need to hold one dev reference there.

otherwise vga_arbiter_del_pci_device that does not check VGA_RSRC_LEGACY_MASK
will call put_device and it will cause ref_count to decrease extra.
that will have that device get deleted early wrongly.

Signed-off-by: Yinghai Lu <yinghai@...nel.org>
Cc: x86@...nel.org

---
 arch/x86/pci/fixup.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Index: linux-2.6/arch/x86/pci/fixup.c
===================================================================
--- linux-2.6.orig/arch/x86/pci/fixup.c
+++ linux-2.6/arch/x86/pci/fixup.c
@@ -349,8 +349,12 @@ static void __devinit pci_fixup_video(st
 	if (config & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
 		pdev->resource[PCI_ROM_RESOURCE].flags |= IORESOURCE_ROM_SHADOW;
 		dev_printk(KERN_DEBUG, &pdev->dev, "Boot video device\n");
-		if (!vga_default_device())
+		if (!vga_default_device()) {
+#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
+			pdev = pci_dev_get(pdev);
+#endif
 			vga_set_default_device(pdev);
+		}
 	}
 }
 DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_ANY_ID, PCI_ANY_ID,
--
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