This patch introduces two root bridge hotplug safe interfaces to walk
all root buses. Function pci_get_root_buses() takes a snopshot of the
pci_root_buses list and holds a reference count to each root buses.
pci_{get|put}_root_buses are used to replace hotplug unsafe interface
pci_find_next_bus().
Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
---
Hi Bjorn,
How about this solution? We could avoid the global lock by
taking a snapshot of the pci_root_buses list.
These two patches just pass basic compilation tests on x86:)
Regards!
Gerry
---
arch/ia64/hp/common/sba_iommu.c | 10 +++++++---
arch/ia64/sn/kernel/io_common.c | 12 ++++++-----
arch/sparc/kernel/pci.c | 15 ++++++++------
arch/x86/pci/common.c | 10 ++++++++--
drivers/edac/i7core_edac.c | 9 ++++++---
drivers/gpu/drm/drm_fops.c | 10 +++++++---
drivers/pci/hotplug/sgi_hotplug.c | 7 ++++++-
drivers/pci/pci-sysfs.c | 9 ++++++---
drivers/pci/search.c | 40 +++++++++++++++++++++++++++++++++++++
include/linux/pci.h | 11 ++++++++++
10 files changed, 107 insertions(+), 26 deletions(-)
diff --git a/arch/ia64/hp/common/sba_iommu.c b/arch/ia64/hp/common/sba_iommu.c
index bcda5b2..2903c58 100644
--- a/arch/ia64/hp/common/sba_iommu.c
+++ b/arch/ia64/hp/common/sba_iommu.c
@@ -2155,9 +2155,13 @@ sba_init(void)
#ifdef CONFIG_PCI
{
- struct pci_bus *b = NULL;
- while ((b = pci_find_next_bus(b)) != NULL)
- sba_connect_bus(b);
+ int i, count;
+ struct pci_bus **buses = NULL;
+
+ buses = pci_get_root_buses(&count);
+ for (i = 0; i < count; i++)
+ sba_connect_bus(buses[i]);
+ pci_put_root_buses(buses, count);
}
#endif
diff --git a/arch/ia64/sn/kernel/io_common.c b/arch/ia64/sn/kernel/io_common.c
index 8630875..f667971 100644
--- a/arch/ia64/sn/kernel/io_common.c
+++ b/arch/ia64/sn/kernel/io_common.c
@@ -516,7 +516,8 @@ arch_initcall(sn_io_early_init);
int __init
sn_io_late_init(void)
{
- struct pci_bus *bus;
+ int i, count;
+ struct pci_bus **buses
struct pcibus_bussoft *bussoft;
cnodeid_t cnode;
nasid_t nasid;
@@ -530,9 +531,9 @@ sn_io_late_init(void)
* PIC, TIOCP, TIOCE (TIOCA does it during bus fixup using
* info from the PROM).
*/
- bus = NULL;
- while ((bus = pci_find_next_bus(bus)) != NULL) {
- bussoft = SN_PCIBUS_BUSSOFT(bus);
+ buses = pci_get_root_buses(&count);
+ for (i = 0; i < count; i++) {
+ bussoft = SN_PCIBUS_BUSSOFT(buses[i]);
nasid = NASID_GET(bussoft->bs_base);
cnode = nasid_to_cnodeid(nasid);
if ((bussoft->bs_asic_type == PCIIO_ASIC_TYPE_TIOCP) ||
@@ -547,9 +548,10 @@ sn_io_late_init(void)
"to find near node with CPUs for "
"node %d, err=%d\n", cnode, e);
}
- PCI_CONTROLLER(bus)->node = near_cnode;
+ PCI_CONTROLLER(buses[i])->node = near_cnode;
}
}
+ pci_put_root_buses(buses, count);
sn_ioif_inited = 1; /* SN I/O infrastructure now initialized */
diff --git a/arch/sparc/kernel/pci.c b/arch/sparc/kernel/pci.c
index 0e8f43a..00d2a83 100644
--- a/arch/sparc/kernel/pci.c
+++ b/arch/sparc/kernel/pci.c
@@ -1005,23 +1005,26 @@ static void __devinit pci_bus_slot_names(struct device_node *node,
static int __init of_pci_slot_init(void)
{
- struct pci_bus *pbus = NULL;
+ int i, count;
+ struct pci_bus **buses;
- while ((pbus = pci_find_next_bus(pbus)) != NULL) {
+ buses = pci_get_root_buses(&count);
+ for (i = 0; i < count; i++) {
struct device_node *node;
- if (pbus->self) {
+ if (buses[i]->self) {
/* PCI->PCI bridge */
- node = pbus->self->dev.of_node;
+ node = buses[i]->self->dev.of_node;
} else {
- struct pci_pbm_info *pbm = pbus->sysdata;
+ struct pci_pbm_info *pbm = buses[i]->sysdata;
/* Host PCI controller */
node = pbm->op->dev.of_node;
}
- pci_bus_slot_names(node, pbus);
+ pci_bus_slot_names(node, buses[i]);
}
+ pci_put_root_buses(buses, count);
return 0;
}
diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 720e973f..986be6e 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -446,14 +446,20 @@ void __init dmi_check_pciprobe(void)
struct pci_bus * __devinit pcibios_scan_root(int busnum)
{
- struct pci_bus *bus = NULL;
+ int i, count;
+ struct pci_bus *bus;
+ struct pci_bus **buses;
- while ((bus = pci_find_next_bus(bus)) != NULL) {
+ buses = pci_get_root_buses(&count);
+ for (i = 0; i < count; i++) {
+ bus = buses[i];
if (bus->number == busnum) {
+ pci_put_root_buses(buses, count);
/* Already scanned */
return bus;
}
}
+ pci_put_root_buses(buses, count);
return pci_scan_bus_on_node(busnum, &pci_root_ops,
get_mp_bus_to_node(busnum));
diff --git a/drivers/edac/i7core_edac.c b/drivers/edac/i7core_edac.c
index 3672101..4f4b221 100644
--- a/drivers/edac/i7core_edac.c
+++ b/drivers/edac/i7core_edac.c
@@ -1294,14 +1294,17 @@ static void __init i7core_xeon_pci_fixup(const struct pci_id_table *table)
static unsigned i7core_pci_lastbus(void)
{
int last_bus = 0, bus;
- struct pci_bus *b = NULL;
+ int i, count;
+ struct pci_bus **buses;
- while ((b = pci_find_next_bus(b)) != NULL) {
- bus = b->number;
+ buses = pci_get_root_buses(&count);
+ for (i = 0; i < count; i++) {
+ bus = buses[i]->number;
edac_dbg(0, "Found bus %d\n", bus);
if (bus > last_bus)
last_bus = bus;
}
+ pci_put_root_buses(buses, count);
edac_dbg(0, "Last bus %d\n", last_bus);
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 5062eec..1a9955f 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -340,9 +340,13 @@ static int drm_open_helper(struct inode *inode, struct file *filp,
pci_dev_put(pci_dev);
}
if (!dev->hose) {
- struct pci_bus *b = pci_bus_b(pci_root_buses.next);
- if (b)
- dev->hose = b->sysdata;
+ int count;
+ struct pci_bus **buses;
+
+ buses = pci_get_root_buses(&count);
+ if (count > 0)
+ dev->hose = buses[0]->sysdata;
+ pci_put_root_buses(buses, count);
}
}
#endif
diff --git a/drivers/pci/hotplug/sgi_hotplug.c b/drivers/pci/hotplug/sgi_hotplug.c
index f64ca92..6ec3ecb 100644
--- a/drivers/pci/hotplug/sgi_hotplug.c
+++ b/drivers/pci/hotplug/sgi_hotplug.c
@@ -679,8 +679,10 @@ alloc_err:
static int __init sn_pci_hotplug_init(void)
{
struct pci_bus *pci_bus = NULL;
+ struct pci_bus **buses;
int rc;
int registered = 0;
+ int i, count;
if (!sn_prom_feature_available(PRF_HOTPLUG_SUPPORT)) {
printk(KERN_ERR "%s: PROM version does not support hotplug.\n",
@@ -690,7 +692,9 @@ static int __init sn_pci_hotplug_init(void)
INIT_LIST_HEAD(&sn_hp_list);
- while ((pci_bus = pci_find_next_bus(pci_bus))) {
+ buses = pci_get_root_buses(&count);
+ for (i = 0; i < count; i++) {
+ pci_bus = buses[i];
if (!pci_bus->sysdata)
continue;
@@ -709,6 +713,7 @@ static int __init sn_pci_hotplug_init(void)
break;
}
}
+ pci_put_root_buses(buses, count);
return registered == 1 ? 0 : -ENODEV;
}
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 6869009..f8e9309 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -290,15 +290,18 @@ static ssize_t bus_rescan_store(struct bus_type *bus, const char *buf,
size_t count)
{
unsigned long val;
- struct pci_bus *b = NULL;
+ int i, num;
+ struct pci_bus **buses;
if (strict_strtoul(buf, 0, &val) < 0)
return -EINVAL;
if (val) {
mutex_lock(&pci_remove_rescan_mutex);
- while ((b = pci_find_next_bus(b)) != NULL)
- pci_rescan_bus(b);
+ buses = pci_get_root_buses(&num);
+ for (i = 0; i < num; i++)
+ pci_rescan_bus(buses[i]);
+ pci_put_root_buses(buses, num);
mutex_unlock(&pci_remove_rescan_mutex);
}
return count;
diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index 8f68dbe..8b20a33 100644
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -140,6 +140,46 @@ pci_find_next_bus(const struct pci_bus *from)
return b;
}
+struct pci_bus **
+pci_get_root_buses(int *bus_num)
+{
+ int count;
+ struct pci_bus *bus;
+ struct pci_bus **buses = NULL;
+
+ down_read(&pci_bus_sem);
+
+ count = 0;
+ list_for_each_entry(bus, &pci_root_buses, node)
+ count++;
+
+ if (count)
+ buses = kmalloc(sizeof(*buses) * count, GFP_KERNEL);
+
+ if (buses) {
+ count = 0;
+ list_for_each_entry(bus, &pci_root_buses, node)
+ buses[count++] = pci_bus_get(bus);
+ *bus_num = count;
+ } else
+ *bus_num = 0;
+
+ up_read(&pci_bus_sem);
+
+ return buses;
+}
+EXPORT_SYMBOL(pci_get_root_buses);
+
+void pci_put_root_buses(struct pci_bus **buses, int count)
+{
+ int i;
+
+ for (i = 0; i < count; i++)
+ pci_bus_put(buses[i]);
+ kfree(buses);
+}
+EXPORT_SYMBOL(pci_put_root_buses);
+
/**
* pci_get_slot - locate PCI device for a given PCI slot
* @bus: PCI bus on which desired PCI device resides
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 98de988..bc1ab5f 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -757,6 +757,8 @@ int pci_find_next_ext_capability(struct pci_dev *dev, int pos, int cap);
int pci_find_ht_capability(struct pci_dev *dev, int ht_cap);
int pci_find_next_ht_capability(struct pci_dev *dev, int pos, int ht_cap);
struct pci_bus *pci_find_next_bus(const struct pci_bus *from);
+struct pci_bus ** pci_get_root_buses(int *bus_num);
+void pci_put_root_buses(struct pci_bus **buses, int count);
struct pci_dev *pci_get_device(unsigned int vendor, unsigned int device,
struct pci_dev *from);
@@ -1402,6 +1404,15 @@ static inline void pci_unblock_cfg_access(struct pci_dev *dev)
static inline struct pci_bus *pci_find_next_bus(const struct pci_bus *from)
{ return NULL; }
+static inline struct pci_bus ** pci_get_root_buses(int *bus_num)
+{
+ *bus_num = 0;
+ return NULL;
+}
+
+static inline void pci_put_root_buses(struct pci_bus **buses, int count)
+{ }
+
static inline struct pci_dev *pci_get_slot(struct pci_bus *bus,
unsigned int devfn)
{ return NULL; }
--
1.7.9.5
--
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