linux/drivers/pci/hotplug/shpchp_pci.c
Mika Westerberg 0f4bd8014d PCI: hotplug: Drop checking of PCI_BRIDGE_CONTROL in *_unconfigure_device()
When removing a bridge, pciehp_unconfigure_device() reads the
PCI_BRIDGE_CONTROL byte.  If this is a surprise hot-unplug, the device is
already gone and the read returns ~0, which pciehp_unconfigure_device()
interprets as having PCI_BRIDGE_CTL_VGA set.  This results in failure of
the remove operation:

  pciehp 0000:00:1c.0:pcie004: Slot(0): Link Down
  pciehp 0000:00:1c.0:pcie004: Slot(0): Card present
  pciehp 0000:00:1c.0:pcie004: Cannot remove display device 0000:01:00.0

Because of this the hierarchy is left untouched preventing further hotplug
operations.

Now, it is not clear why the check is there in the first place and why we
would like to prevent removing a bridge if it has PCI_BRIDGE_CTL_VGA set.
In case of PCIe surprise hot-unplug, it would not even be possible to
prevent the removal.

Given this and the issue described above, I think it makes sense to drop
the whole PCI_BRIDGE_CONTROL check from pciehp_unconfigure_device().  While
there do the same for shpchp_configure_device() based on the same reasoning
and the fact that the same bug might trigger in standard PCI hotplug as
well.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[bhelgaas: changelog]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
2017-12-18 23:05:18 -06:00

103 lines
2.7 KiB
C

/*
* Standard Hot Plug Controller Driver
*
* Copyright (C) 1995,2001 Compaq Computer Corporation
* Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
* Copyright (C) 2001 IBM Corp.
* Copyright (C) 2003-2004 Intel Corporation
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Send feedback to <greg@kroah.com>, <kristen.c.accardi@intel.com>
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/pci.h>
#include "../pci.h"
#include "shpchp.h"
int shpchp_configure_device(struct slot *p_slot)
{
struct pci_dev *dev;
struct controller *ctrl = p_slot->ctrl;
struct pci_dev *bridge = ctrl->pci_dev;
struct pci_bus *parent = bridge->subordinate;
int num, ret = 0;
pci_lock_rescan_remove();
dev = pci_get_slot(parent, PCI_DEVFN(p_slot->device, 0));
if (dev) {
ctrl_err(ctrl, "Device %s already exists at %04x:%02x:%02x, cannot hot-add\n",
pci_name(dev), pci_domain_nr(parent),
p_slot->bus, p_slot->device);
pci_dev_put(dev);
ret = -EINVAL;
goto out;
}
num = pci_scan_slot(parent, PCI_DEVFN(p_slot->device, 0));
if (num == 0) {
ctrl_err(ctrl, "No new device found\n");
ret = -ENODEV;
goto out;
}
for_each_pci_bridge(dev, parent) {
if (PCI_SLOT(dev->devfn) == p_slot->device)
pci_hp_add_bridge(dev);
}
pci_assign_unassigned_bridge_resources(bridge);
pcie_bus_configure_settings(parent);
pci_bus_add_devices(parent);
out:
pci_unlock_rescan_remove();
return ret;
}
int shpchp_unconfigure_device(struct slot *p_slot)
{
int rc = 0;
struct pci_bus *parent = p_slot->ctrl->pci_dev->subordinate;
struct pci_dev *dev, *temp;
struct controller *ctrl = p_slot->ctrl;
ctrl_dbg(ctrl, "%s: domain:bus:dev = %04x:%02x:%02x\n",
__func__, pci_domain_nr(parent), p_slot->bus, p_slot->device);
pci_lock_rescan_remove();
list_for_each_entry_safe(dev, temp, &parent->devices, bus_list) {
if (PCI_SLOT(dev->devfn) != p_slot->device)
continue;
pci_dev_get(dev);
pci_stop_and_remove_bus_device(dev);
pci_dev_put(dev);
}
pci_unlock_rescan_remove();
return rc;
}