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[SCSI] gdth: Remove buggy ROM handling

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The ROM address handling in gdth_init_pci() is useless and possibly
dangerous.  This patch removes it.

"pci_resource_start(pdev, 8)" is not well-defined.  PCI resources 0-5 are
standard PCI BARs and 6 is the expansion ROM.  Resource 8 is either an
SR-IOV BAR (if CONFIG_PCI_IOV=y, resources 7-12 are SR-IOV BARs) or a
bridge window (resources 7-10).

The GDT device is neither an SR-IOV device nor a bridge, so in either case
resource 8 should be zero since struct pci_dev is allocated with kzalloc().

It is illegal for a driver to write an arbitrary address to the ROM BAR
because it has no way of knowing whether the ROM will conflict with another
device.

I think the only effect of the code being removed was to:

  1) Enable the ROM at 0xFEFF0000 (possibly causing a conflict with
     another device)
  2) Delay one millisecond
  3) Write zero to the ROM BAR, disabling it

I doubt the delay is needed, but I left it since it seems innocuous.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This commit is contained in:
Bjorn Helgaas 2012-11-06 15:04:44 -07:00 committed by James Bottomley
parent f94d4fe0b5
commit 8108de9739
1 changed files with 2 additions and 8 deletions
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10
drivers/scsi/gdth.c
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@ -1107,14 +1107,8 @@ static int gdth_init_pci(struct pci_dev *pdev, gdth_pci_str *pcistr,
pci_read_config_word(pdev, PCI_COMMAND, &command);
command |= 6;
pci_write_config_word(pdev, PCI_COMMAND, command);
if (pci_resource_start(pdev, 8) == 1UL)
pci_resource_start(pdev, 8) = 0UL;
i = 0xFEFF0001UL;
pci_write_config_dword(pdev, PCI_ROM_ADDRESS, i);
gdth_delay(1);
pci_write_config_dword(pdev, PCI_ROM_ADDRESS,
pci_resource_start(pdev, 8));
gdth_delay(1);
dp6m_ptr = ha->brd;
/* Ensure that it is safe to access the non HW portions of DPMEM.