Niklas Schnelle
f86ca2b553
commit 47c397844869ad0e6738afb5879c7492f4691122 upstream.
As disable_slot() takes a struct zpci_dev from the Configured to the
Standby state. In Standby there is still a hotplug slot so this is not
usually a case of sysfs self deletion. This is important because self
deletion gets very hairy in terms of locking (see for example
recover_store() in arch/s390/pci/pci_sysfs.c).
Because the pci_dev_put() is not within the critical section of the
zdev->state_lock however, disable_slot() can turn into a case of self
deletion if zPCI device event handling slips between the mutex_unlock()
and the pci_dev_put(). If the latter is the last put and
zpci_release_device() is called this then tries to remove the hotplug
slot via zpci_exit_slot() which will try to remove the hotplug slot
directory the disable_slot() is part of i.e. self deletion.
Prevent this by widening the zdev->state_lock critical section to
include the pci_dev_put() which is then guaranteed to happen with the
struct zpci_dev still in Standby state ensuring it will not lead to
a zpci_release_device() call as at least the zPCI event handling code
still holds a reference.
Cc: stable@vger.kernel.org
Fixes: a46044a92a ("s390/pci: fix zpci_zdev_put() on reserve")
Reviewed-by: Gerd Bayer <gbayer@linux.ibm.com>
Tested-by: Gerd Bayer <gbayer@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
143 lines
3.1 KiB
C
143 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* PCI Hot Plug Controller Driver for System z
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*
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* Copyright 2012 IBM Corp.
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*
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* Author(s):
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* Jan Glauber <jang@linux.vnet.ibm.com>
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*/
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#define KMSG_COMPONENT "zpci"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/pci.h>
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#include <linux/pci_hotplug.h>
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#include <asm/pci_debug.h>
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#include <asm/sclp.h>
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#define SLOT_NAME_SIZE 10
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static int enable_slot(struct hotplug_slot *hotplug_slot)
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{
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struct zpci_dev *zdev = container_of(hotplug_slot, struct zpci_dev,
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hotplug_slot);
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int rc;
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mutex_lock(&zdev->state_lock);
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if (zdev->state != ZPCI_FN_STATE_STANDBY) {
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rc = -EIO;
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goto out;
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}
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rc = sclp_pci_configure(zdev->fid);
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zpci_dbg(3, "conf fid:%x, rc:%d\n", zdev->fid, rc);
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if (rc)
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goto out;
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zdev->state = ZPCI_FN_STATE_CONFIGURED;
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rc = zpci_scan_configured_device(zdev, zdev->fh);
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out:
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mutex_unlock(&zdev->state_lock);
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return rc;
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}
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static int disable_slot(struct hotplug_slot *hotplug_slot)
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{
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struct zpci_dev *zdev = container_of(hotplug_slot, struct zpci_dev,
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hotplug_slot);
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struct pci_dev *pdev = NULL;
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int rc;
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mutex_lock(&zdev->state_lock);
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if (zdev->state != ZPCI_FN_STATE_CONFIGURED) {
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rc = -EIO;
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goto out;
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}
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pdev = pci_get_slot(zdev->zbus->bus, zdev->devfn);
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if (pdev && pci_num_vf(pdev)) {
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rc = -EBUSY;
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goto out;
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}
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rc = zpci_deconfigure_device(zdev);
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out:
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if (pdev)
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pci_dev_put(pdev);
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mutex_unlock(&zdev->state_lock);
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return rc;
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}
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static int reset_slot(struct hotplug_slot *hotplug_slot, bool probe)
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{
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struct zpci_dev *zdev = container_of(hotplug_slot, struct zpci_dev,
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hotplug_slot);
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int rc = -EIO;
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/*
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* If we can't get the zdev->state_lock the device state is
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* currently undergoing a transition and we bail out - just
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* the same as if the device's state is not configured at all.
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*/
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if (!mutex_trylock(&zdev->state_lock))
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return rc;
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/* We can reset only if the function is configured */
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if (zdev->state != ZPCI_FN_STATE_CONFIGURED)
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goto out;
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if (probe) {
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rc = 0;
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goto out;
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}
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rc = zpci_hot_reset_device(zdev);
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out:
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mutex_unlock(&zdev->state_lock);
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return rc;
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}
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static int get_power_status(struct hotplug_slot *hotplug_slot, u8 *value)
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{
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struct zpci_dev *zdev = container_of(hotplug_slot, struct zpci_dev,
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hotplug_slot);
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*value = zpci_is_device_configured(zdev) ? 1 : 0;
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return 0;
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}
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static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
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{
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/* if the slot exists it always contains a function */
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*value = 1;
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return 0;
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}
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static const struct hotplug_slot_ops s390_hotplug_slot_ops = {
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.enable_slot = enable_slot,
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.disable_slot = disable_slot,
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.reset_slot = reset_slot,
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.get_power_status = get_power_status,
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.get_adapter_status = get_adapter_status,
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};
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int zpci_init_slot(struct zpci_dev *zdev)
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{
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char name[SLOT_NAME_SIZE];
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struct zpci_bus *zbus = zdev->zbus;
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zdev->hotplug_slot.ops = &s390_hotplug_slot_ops;
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snprintf(name, SLOT_NAME_SIZE, "%08x", zdev->fid);
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return pci_hp_register(&zdev->hotplug_slot, zbus->bus,
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zdev->devfn, name);
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}
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void zpci_exit_slot(struct zpci_dev *zdev)
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{
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pci_hp_deregister(&zdev->hotplug_slot);
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}
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