x86/PCI: use RCU list to protect mmconfig list

Use RCU list to protect mmconfig list from dynamic change
when supporting PCI host bridge hotplug.

Reviewed-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

3 files changed, 34 insertions, 10 deletions

diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
index 5e2cd2aa2889..0ac97d54bcac 100644
--- a/arch/x86/pci/mmconfig-shared.c
+++ b/arch/x86/pci/mmconfig-shared.c
@@ -17,6 +17,8 @@
 #include <linux/bitmap.h>
 #include <linux/dmi.h>
 #include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/rculist.h>
 #include <asm/e820.h>
 #include <asm/pci_x86.h>
 #include <asm/acpi.h>
@@ -25,6 +27,7 @@
 
 /* Indicate if the mmcfg resources have been placed into the resource table. */
 static int __initdata pci_mmcfg_resources_inserted;
+static DEFINE_MUTEX(pci_mmcfg_lock);
 
 LIST_HEAD(pci_mmcfg_list);
 
@@ -45,20 +48,20 @@ static __init void free_all_mmcfg(void)
                 pci_mmconfig_remove(cfg);
 }
 
-static __init void list_add_sorted(struct pci_mmcfg_region *new)
+static __devinit void list_add_sorted(struct pci_mmcfg_region *new)
 {
         struct pci_mmcfg_region *cfg;
 
         /* keep list sorted by segment and starting bus number */
-        list_for_each_entry(cfg, &pci_mmcfg_list, list) {
+        list_for_each_entry_rcu(cfg, &pci_mmcfg_list, list) {
                 if (cfg->segment > new->segment ||
                     (cfg->segment == new->segment &&
                      cfg->start_bus >= new->start_bus)) {
-                        list_add_tail(&new->list, &cfg->list);
+                        list_add_tail_rcu(&new->list, &cfg->list);
                         return;
                 }
         }
-        list_add_tail(&new->list, &pci_mmcfg_list);
+        list_add_tail_rcu(&new->list, &pci_mmcfg_list);
 }
 
 static __devinit struct pci_mmcfg_region *pci_mmconfig_alloc(int segment,
@@ -101,8 +104,11 @@ static __init struct pci_mmcfg_region *pci_mmconfig_add(int segment, int start,
         struct pci_mmcfg_region *new;
 
         new = pci_mmconfig_alloc(segment, start, end, addr);
-        if (new)
+        if (new) {
+                mutex_lock(&pci_mmcfg_lock);
                 list_add_sorted(new);
+                mutex_unlock(&pci_mmcfg_lock);
+        }
 
         return new;
 }
@@ -111,7 +117,7 @@ struct pci_mmcfg_region *pci_mmconfig_lookup(int segment, int bus)
 {
         struct pci_mmcfg_region *cfg;
 
-        list_for_each_entry(cfg, &pci_mmcfg_list, list)
+        list_for_each_entry_rcu(cfg, &pci_mmcfg_list, list)
                 if (cfg->segment == segment &&
                     cfg->start_bus <= bus && bus <= cfg->end_bus)
                         return cfg;
diff --git a/arch/x86/pci/mmconfig_32.c b/arch/x86/pci/mmconfig_32.c
index 5372e86834c0..5dad04aa6b37 100644
--- a/arch/x86/pci/mmconfig_32.c
+++ b/arch/x86/pci/mmconfig_32.c
@@ -11,6 +11,7 @@
 
 #include <linux/pci.h>
 #include <linux/init.h>
+#include <linux/rcupdate.h>
 #include <asm/e820.h>
 #include <asm/pci_x86.h>
 #include <acpi/acpi.h>
@@ -60,9 +61,12 @@ err:		*value = -1;
                 return -EINVAL;
         }
 
+        rcu_read_lock();
         base = get_base_addr(seg, bus, devfn);
-        if (!base)
+        if (!base) {
+                rcu_read_unlock();
                 goto err;
+        }
 
         raw_spin_lock_irqsave(&pci_config_lock, flags);
 
@@ -80,6 +84,7 @@ err:		*value = -1;
                 break;
         }
         raw_spin_unlock_irqrestore(&pci_config_lock, flags);
+        rcu_read_unlock();
 
         return 0;
 }
@@ -93,9 +98,12 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
         if ((bus > 255) || (devfn > 255) || (reg > 4095))
                 return -EINVAL;
 
+        rcu_read_lock();
         base = get_base_addr(seg, bus, devfn);
-        if (!base)
+        if (!base) {
+                rcu_read_unlock();
                 return -EINVAL;
+        }
 
         raw_spin_lock_irqsave(&pci_config_lock, flags);
 
@@ -113,6 +121,7 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
                 break;
         }
         raw_spin_unlock_irqrestore(&pci_config_lock, flags);
+        rcu_read_unlock();
 
         return 0;
 }
diff --git a/arch/x86/pci/mmconfig_64.c b/arch/x86/pci/mmconfig_64.c
index 915a493502cb..acc48c5b6863 100644
--- a/arch/x86/pci/mmconfig_64.c
+++ b/arch/x86/pci/mmconfig_64.c
@@ -9,6 +9,7 @@
 #include <linux/init.h>
 #include <linux/acpi.h>
 #include <linux/bitmap.h>
+#include <linux/rcupdate.h>
 #include <asm/e820.h>
 #include <asm/pci_x86.h>
 
@@ -34,9 +35,12 @@ err:		*value = -1;
                 return -EINVAL;
         }
 
+        rcu_read_lock();
         addr = pci_dev_base(seg, bus, devfn);
-        if (!addr)
+        if (!addr) {
+                rcu_read_unlock();
                 goto err;
+        }
 
         switch (len) {
         case 1:
@@ -49,6 +53,7 @@ err:		*value = -1;
                 *value = mmio_config_readl(addr + reg);
                 break;
         }
+        rcu_read_unlock();
 
         return 0;
 }
@@ -62,9 +67,12 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
         if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
                 return -EINVAL;
 
+        rcu_read_lock();
         addr = pci_dev_base(seg, bus, devfn);
-        if (!addr)
+        if (!addr) {
+                rcu_read_unlock();
                 return -EINVAL;
+        }
 
         switch (len) {
         case 1:
@@ -77,6 +85,7 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
                 mmio_config_writel(addr + reg, value);
                 break;
         }
+        rcu_read_unlock();
 
         return 0;
 }