[PATCH 5/9] PCI / hotplug: Use global PCI rescan-remove locking

From: Rafael J. Wysocki
Date: Fri Jan 10 2014 - 09:18:30 EST

From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

Multiple race conditions are possible between PCI hotplug and the
generic PCI bus rescan and device removal that can be triggered via
sysfs.

To avoid those race conditions make PCI hotplug use global PCI
rescan-remove locking.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
drivers/pci/hotplug/cpci_hotplug_pci.c | 14 ++++++++++++--
drivers/pci/hotplug/cpqphp_pci.c | 8 +++++++-
drivers/pci/hotplug/ibmphp_core.c | 13 +++++++++++--
drivers/pci/hotplug/pciehp_pci.c | 17 +++++++++++++----
drivers/pci/hotplug/rpadlpar_core.c | 19 ++++++++++++++-----
drivers/pci/hotplug/rpaphp_core.c | 4 ++++
drivers/pci/hotplug/s390_pci_hpc.c | 4 +++-
drivers/pci/hotplug/sgi_hotplug.c | 5 +++++
drivers/pci/hotplug/shpchp_pci.c | 18 ++++++++++++++----
9 files changed, 83 insertions(+), 19 deletions(-)

Index: linux-pm/drivers/pci/hotplug/rpadlpar_core.c
===================================================================
--- linux-pm.orig/drivers/pci/hotplug/rpadlpar_core.c
+++ linux-pm/drivers/pci/hotplug/rpadlpar_core.c
@@ -354,10 +354,15 @@ int dlpar_remove_pci_slot(char *drc_name
{
struct pci_bus *bus;
struct slot *slot;
+ int ret = 0;
+
+ pci_lock_rescan_remove();

bus = pcibios_find_pci_bus(dn);
- if (!bus)
- return -EINVAL;
+ if (!bus) {
+ ret = -EINVAL;
+ goto out;
+ }

pr_debug("PCI: Removing PCI slot below EADS bridge %s\n",
bus->self ? pci_name(bus->self) : "<!PHB!>");
@@ -371,7 +376,8 @@ int dlpar_remove_pci_slot(char *drc_name
printk(KERN_ERR
"%s: unable to remove hotplug slot %s\n",
__func__, drc_name);
- return -EIO;
+ ret = -EIO;
+ goto out;
}
}

@@ -382,7 +388,8 @@ int dlpar_remove_pci_slot(char *drc_name
if (pcibios_unmap_io_space(bus)) {
printk(KERN_ERR "%s: failed to unmap bus range\n",
__func__);
- return -ERANGE;
+ ret = -ERANGE;
+ goto out;
}

/* Remove the EADS bridge device itself */
@@ -390,7 +397,9 @@ int dlpar_remove_pci_slot(char *drc_name
pr_debug("PCI: Now removing bridge device %s\n", pci_name(bus->self));
pci_stop_and_remove_bus_device(bus->self);

- return 0;
+ out:
+ pci_unlock_rescan_remove();
+ return ret;
}

/**
Index: linux-pm/drivers/pci/hotplug/cpci_hotplug_pci.c
===================================================================
--- linux-pm.orig/drivers/pci/hotplug/cpci_hotplug_pci.c
+++ linux-pm/drivers/pci/hotplug/cpci_hotplug_pci.c
@@ -254,9 +254,12 @@ int __ref cpci_configure_slot(struct slo
{
struct pci_dev *dev;
struct pci_bus *parent;
+ int ret = 0;

dbg("%s - enter", __func__);

+ pci_lock_rescan_remove();
+
if (slot->dev == NULL) {
dbg("pci_dev null, finding %02x:%02x:%x",
slot->bus->number, PCI_SLOT(slot->devfn), PCI_FUNC(slot->devfn));
@@ -277,7 +280,8 @@ int __ref cpci_configure_slot(struct slo
slot->dev = pci_get_slot(slot->bus, slot->devfn);
if (slot->dev == NULL) {
err("Could not find PCI device for slot %02x", slot->number);
- return -ENODEV;
+ ret = -ENODEV;
+ goto out;
}
}
parent = slot->dev->bus;
@@ -294,8 +298,10 @@ int __ref cpci_configure_slot(struct slo

pci_bus_add_devices(parent);

+ out:
+ pci_unlock_rescan_remove();
dbg("%s - exit", __func__);
- return 0;
+ return ret;
}

int cpci_unconfigure_slot(struct slot* slot)
@@ -308,6 +314,8 @@ int cpci_unconfigure_slot(struct slot* s
return -ENODEV;
}

+ pci_lock_rescan_remove();
+
list_for_each_entry_safe(dev, temp, &slot->bus->devices, bus_list) {
if (PCI_SLOT(dev->devfn) != PCI_SLOT(slot->devfn))
continue;
@@ -318,6 +326,8 @@ int cpci_unconfigure_slot(struct slot* s
pci_dev_put(slot->dev);
slot->dev = NULL;

+ pci_unlock_rescan_remove();
+
dbg("%s - exit", __func__);
return 0;
}
Index: linux-pm/drivers/pci/hotplug/pciehp_pci.c
===================================================================
--- linux-pm.orig/drivers/pci/hotplug/pciehp_pci.c
+++ linux-pm/drivers/pci/hotplug/pciehp_pci.c
@@ -39,22 +39,26 @@ int pciehp_configure_device(struct slot
struct pci_dev *dev;
struct pci_dev *bridge = p_slot->ctrl->pcie->port;
struct pci_bus *parent = bridge->subordinate;
- int num;
+ int num, ret = 0;
struct controller *ctrl = p_slot->ctrl;

+ pci_lock_rescan_remove();
+
dev = pci_get_slot(parent, PCI_DEVFN(0, 0));
if (dev) {
ctrl_err(ctrl, "Device %s already exists "
"at %04x:%02x:00, cannot hot-add\n", pci_name(dev),
pci_domain_nr(parent), parent->number);
pci_dev_put(dev);
- return -EINVAL;
+ ret = -EINVAL;
+ goto out;
}

num = pci_scan_slot(parent, PCI_DEVFN(0, 0));
if (num == 0) {
ctrl_err(ctrl, "No new device found\n");
- return -ENODEV;
+ ret = -ENODEV;
+ goto out;
}

list_for_each_entry(dev, &parent->devices, bus_list)
@@ -73,7 +77,9 @@ int pciehp_configure_device(struct slot

pci_bus_add_devices(parent);

- return 0;
+ out:
+ pci_unlock_rescan_remove();
+ return ret;
}

int pciehp_unconfigure_device(struct slot *p_slot)
@@ -92,6 +98,8 @@ int pciehp_unconfigure_device(struct slo
if (ret)
presence = 0;

+ pci_lock_rescan_remove();
+
/*
* Stopping an SR-IOV PF device removes all the associated VFs,
* which will update the bus->devices list and confuse the
@@ -126,5 +134,6 @@ int pciehp_unconfigure_device(struct slo
pci_dev_put(dev);
}

+ pci_unlock_rescan_remove();
return rc;
}
Index: linux-pm/drivers/pci/hotplug/cpqphp_pci.c
===================================================================
--- linux-pm.orig/drivers/pci/hotplug/cpqphp_pci.c
+++ linux-pm/drivers/pci/hotplug/cpqphp_pci.c
@@ -86,6 +86,8 @@ int cpqhp_configure_device (struct contr
struct pci_bus *child;
int num;

+ pci_lock_rescan_remove();
+
if (func->pci_dev == NULL)
func->pci_dev = pci_get_bus_and_slot(func->bus,PCI_DEVFN(func->device, func->function));

@@ -100,7 +102,7 @@ int cpqhp_configure_device (struct contr
func->pci_dev = pci_get_bus_and_slot(func->bus, PCI_DEVFN(func->device, func->function));
if (func->pci_dev == NULL) {
dbg("ERROR: pci_dev still null\n");
- return 0;
+ goto out;
}
}

@@ -113,6 +115,8 @@ int cpqhp_configure_device (struct contr

pci_dev_put(func->pci_dev);

+ out:
+ pci_unlock_rescan_remove();
return 0;
}

@@ -123,6 +127,7 @@ int cpqhp_unconfigure_device(struct pci_

dbg("%s: bus/dev/func = %x/%x/%x\n", __func__, func->bus, func->device, func->function);

+ pci_lock_rescan_remove();
for (j=0; j<8 ; j++) {
struct pci_dev* temp = pci_get_bus_and_slot(func->bus, PCI_DEVFN(func->device, j));
if (temp) {
@@ -130,6 +135,7 @@ int cpqhp_unconfigure_device(struct pci_
pci_stop_and_remove_bus_device(temp);
}
}
+ pci_unlock_rescan_remove();
return 0;
}

Index: linux-pm/drivers/pci/hotplug/ibmphp_core.c
===================================================================
--- linux-pm.orig/drivers/pci/hotplug/ibmphp_core.c
+++ linux-pm/drivers/pci/hotplug/ibmphp_core.c
@@ -718,6 +718,8 @@ static void ibm_unconfigure_device(struc
func->device, func->function);
debug("func->device << 3 | 0x0 = %x\n", func->device << 3 | 0x0);

+ pci_lock_rescan_remove();
+
for (j = 0; j < 0x08; j++) {
temp = pci_get_bus_and_slot(func->busno, (func->device << 3) | j);
if (temp) {
@@ -725,7 +727,10 @@ static void ibm_unconfigure_device(struc
pci_dev_put(temp);
}
}
+
pci_dev_put(func->dev);
+
+ pci_unlock_rescan_remove();
}

/*
@@ -780,6 +785,8 @@ static int ibm_configure_device(struct p
int flag = 0; /* this is to make sure we don't double scan the bus,
for bridged devices primarily */

+ pci_lock_rescan_remove();
+
if (!(bus_structure_fixup(func->busno)))
flag = 1;
if (func->dev == NULL)
@@ -789,7 +796,7 @@ static int ibm_configure_device(struct p
if (func->dev == NULL) {
struct pci_bus *bus = pci_find_bus(0, func->busno);
if (!bus)
- return 0;
+ goto out;

num = pci_scan_slot(bus,
PCI_DEVFN(func->device, func->function));
@@ -800,7 +807,7 @@ static int ibm_configure_device(struct p
PCI_DEVFN(func->device, func->function));
if (func->dev == NULL) {
err("ERROR... : pci_dev still NULL\n");
- return 0;
+ goto out;
}
}
if (!(flag) && (func->dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)) {
@@ -810,6 +817,8 @@ static int ibm_configure_device(struct p
pci_bus_add_devices(child);
}

+ out:
+ pci_unlock_rescan_remove();
return 0;
}

Index: linux-pm/drivers/pci/hotplug/s390_pci_hpc.c
===================================================================
--- linux-pm.orig/drivers/pci/hotplug/s390_pci_hpc.c
+++ linux-pm/drivers/pci/hotplug/s390_pci_hpc.c
@@ -80,7 +80,9 @@ static int enable_slot(struct hotplug_sl
goto out_deconfigure;

pci_scan_slot(slot->zdev->bus, ZPCI_DEVFN);
+ pci_lock_rescan_remove();
pci_bus_add_devices(slot->zdev->bus);
+ pci_unlock_rescan_remove();

return rc;

@@ -98,7 +100,7 @@ static int disable_slot(struct hotplug_s
return -EIO;

if (slot->zdev->pdev)
- pci_stop_and_remove_bus_device(slot->zdev->pdev);
+ pci_stop_and_remove_bus_device_locked(slot->zdev->pdev);

rc = zpci_disable_device(slot->zdev);
if (rc)
Index: linux-pm/drivers/pci/hotplug/shpchp_pci.c
===================================================================
--- linux-pm.orig/drivers/pci/hotplug/shpchp_pci.c
+++ linux-pm/drivers/pci/hotplug/shpchp_pci.c
@@ -40,7 +40,9 @@ int __ref shpchp_configure_device(struct
struct controller *ctrl = p_slot->ctrl;
struct pci_dev *bridge = ctrl->pci_dev;
struct pci_bus *parent = bridge->subordinate;
- int num;
+ int num, ret = 0;
+
+ pci_lock_rescan_remove();

dev = pci_get_slot(parent, PCI_DEVFN(p_slot->device, 0));
if (dev) {
@@ -48,13 +50,15 @@ int __ref shpchp_configure_device(struct
"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);
- return -EINVAL;
+ 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");
- return -ENODEV;
+ ret = -ENODEV;
+ goto out;
}

list_for_each_entry(dev, &parent->devices, bus_list) {
@@ -75,7 +79,9 @@ int __ref shpchp_configure_device(struct

pci_bus_add_devices(parent);

- return 0;
+ out:
+ pci_unlock_rescan_remove();
+ return ret;
}

int shpchp_unconfigure_device(struct slot *p_slot)
@@ -89,6 +95,8 @@ int shpchp_unconfigure_device(struct slo
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;
@@ -108,6 +116,8 @@ int shpchp_unconfigure_device(struct slo
pci_stop_and_remove_bus_device(dev);
pci_dev_put(dev);
}
+
+ pci_unlock_rescan_remove();
return rc;
}

Index: linux-pm/drivers/pci/hotplug/sgi_hotplug.c
===================================================================
--- linux-pm.orig/drivers/pci/hotplug/sgi_hotplug.c
+++ linux-pm/drivers/pci/hotplug/sgi_hotplug.c
@@ -459,12 +459,15 @@ static int enable_slot(struct hotplug_sl
acpi_scan_lock_release();
}

+ pci_lock_rescan_remove();
+
/* Call the driver for the new device */
pci_bus_add_devices(slot->pci_bus);
/* Call the drivers for the new devices subordinate to PPB */
if (new_ppb)
pci_bus_add_devices(new_bus);

+ pci_unlock_rescan_remove();
mutex_unlock(&sn_hotplug_mutex);

if (rc == 0)
@@ -540,6 +543,7 @@ static int disable_slot(struct hotplug_s
acpi_scan_lock_release();
}

+ pci_lock_rescan_remove();
/* Free the SN resources assigned to the Linux device.*/
list_for_each_entry_safe(dev, temp, &slot->pci_bus->devices, bus_list) {
if (PCI_SLOT(dev->devfn) != slot->device_num + 1)
@@ -550,6 +554,7 @@ static int disable_slot(struct hotplug_s
pci_stop_and_remove_bus_device(dev);
pci_dev_put(dev);
}
+ pci_unlock_rescan_remove();

/* Remove the SSDT for the slot from the ACPI namespace */
if (SN_ACPI_BASE_SUPPORT() && ssdt_id) {
Index: linux-pm/drivers/pci/hotplug/rpaphp_core.c
===================================================================
--- linux-pm.orig/drivers/pci/hotplug/rpaphp_core.c
+++ linux-pm/drivers/pci/hotplug/rpaphp_core.c
@@ -398,7 +398,9 @@ static int enable_slot(struct hotplug_sl
return retval;

if (state == PRESENT) {
+ pci_lock_rescan_remove();
pcibios_add_pci_devices(slot->bus);
+ pci_unlock_rescan_remove();
slot->state = CONFIGURED;
} else if (state == EMPTY) {
slot->state = EMPTY;
@@ -418,7 +420,9 @@ static int disable_slot(struct hotplug_s
if (slot->state == NOT_CONFIGURED)
return -EINVAL;

+ pci_lock_rescan_remove();
pcibios_remove_pci_devices(slot->bus);
+ pci_unlock_rescan_remove();
vm_unmap_aliases();

slot->state = NOT_CONFIGURED;

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