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Subject[PATCH 3.4 07/13] i7300_edac: Fix device reference count
Date
3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jean Delvare <jdelvare@suse.de>

commit 75135da0d68419ef8a925f4c1d5f63d8046e314d upstream.

pci_get_device() decrements the reference count of "from" (last
argument) so when we break off the loop successfully we have only one
device reference - and we don't know which device we have. If we want
a reference to each device, we must take them explicitly and let
the pci_get_device() walk complete to avoid duplicate references.

This is serious, as over-putting device references will cause
the device to eventually disappear. Without this fix, the kernel
crashes after a few insmod/rmmod cycles.

Tested on an Intel S7000FC4UR system with a 7300 chipset.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Link: http://lkml.kernel.org/r/20140224111656.09bbb7ed@endymion.delvare
Cc: Mauro Carvalho Chehab <m.chehab@samsung.com>
Cc: Doug Thompson <dougthompson@xmission.com>
Cc: stable@vger.kernel.org
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/edac/i7300_edac.c | 38 ++++++++++++++++++++------------------
1 file changed, 20 insertions(+), 18 deletions(-)

--- a/drivers/edac/i7300_edac.c
+++ b/drivers/edac/i7300_edac.c
@@ -962,33 +962,35 @@ static int __devinit i7300_get_devices(s

/* Attempt to 'get' the MCH register we want */
pdev = NULL;
- while (!pvt->pci_dev_16_1_fsb_addr_map ||
- !pvt->pci_dev_16_2_fsb_err_regs) {
- pdev = pci_get_device(PCI_VENDOR_ID_INTEL,
- PCI_DEVICE_ID_INTEL_I7300_MCH_ERR, pdev);
- if (!pdev) {
- /* End of list, leave */
- i7300_printk(KERN_ERR,
- "'system address,Process Bus' "
- "device not found:"
- "vendor 0x%x device 0x%x ERR funcs "
- "(broken BIOS?)\n",
- PCI_VENDOR_ID_INTEL,
- PCI_DEVICE_ID_INTEL_I7300_MCH_ERR);
- goto error;
- }
-
+ while ((pdev = pci_get_device(PCI_VENDOR_ID_INTEL,
+ PCI_DEVICE_ID_INTEL_I7300_MCH_ERR,
+ pdev))) {
/* Store device 16 funcs 1 and 2 */
switch (PCI_FUNC(pdev->devfn)) {
case 1:
- pvt->pci_dev_16_1_fsb_addr_map = pdev;
+ if (!pvt->pci_dev_16_1_fsb_addr_map)
+ pvt->pci_dev_16_1_fsb_addr_map =
+ pci_dev_get(pdev);
break;
case 2:
- pvt->pci_dev_16_2_fsb_err_regs = pdev;
+ if (!pvt->pci_dev_16_2_fsb_err_regs)
+ pvt->pci_dev_16_2_fsb_err_regs =
+ pci_dev_get(pdev);
break;
}
}

+ if (!pvt->pci_dev_16_1_fsb_addr_map ||
+ !pvt->pci_dev_16_2_fsb_err_regs) {
+ /* At least one device was not found */
+ i7300_printk(KERN_ERR,
+ "'system address,Process Bus' device not found:"
+ "vendor 0x%x device 0x%x ERR funcs (broken BIOS?)\n",
+ PCI_VENDOR_ID_INTEL,
+ PCI_DEVICE_ID_INTEL_I7300_MCH_ERR);
+ goto error;
+ }
+
debugf1("System Address, processor bus- PCI Bus ID: %s %x:%x\n",
pci_name(pvt->pci_dev_16_0_fsb_ctlr),
pvt->pci_dev_16_0_fsb_ctlr->vendor,



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