iommu/vt-d: Use RCU to protect global resources in interrupt context
Global DMA and interrupt remapping resources may be accessed in
interrupt context, so use RCU instead of rwsem to protect them
in such cases.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>
diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index c9aca88..6e4d851 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -71,13 +71,13 @@
* the very end.
*/
if (drhd->include_all)
- list_add_tail(&drhd->list, &dmar_drhd_units);
+ list_add_tail_rcu(&drhd->list, &dmar_drhd_units);
else
- list_add(&drhd->list, &dmar_drhd_units);
+ list_add_rcu(&drhd->list, &dmar_drhd_units);
}
static int __init dmar_parse_one_dev_scope(struct acpi_dmar_device_scope *scope,
- struct pci_dev **dev, u16 segment)
+ struct pci_dev __rcu **dev, u16 segment)
{
struct pci_bus *bus;
struct pci_dev *pdev = NULL;
@@ -122,7 +122,9 @@
pci_name(pdev));
return -EINVAL;
}
- *dev = pdev;
+
+ rcu_assign_pointer(*dev, pdev);
+
return 0;
}
@@ -149,7 +151,7 @@
}
int __init dmar_parse_dev_scope(void *start, void *end, int *cnt,
- struct pci_dev ***devices, u16 segment)
+ struct pci_dev __rcu ***devices, u16 segment)
{
struct acpi_dmar_device_scope *scope;
int index, ret;
@@ -177,7 +179,7 @@
return 0;
}
-void dmar_free_dev_scope(struct pci_dev ***devices, int *cnt)
+void dmar_free_dev_scope(struct pci_dev __rcu ***devices, int *cnt)
{
int i;
struct pci_dev *tmp_dev;
@@ -186,9 +188,10 @@
for_each_active_dev_scope(*devices, *cnt, i, tmp_dev)
pci_dev_put(tmp_dev);
kfree(*devices);
- *devices = NULL;
- *cnt = 0;
}
+
+ *devices = NULL;
+ *cnt = 0;
}
/**
@@ -410,7 +413,7 @@
return ret;
}
-static int dmar_pci_device_match(struct pci_dev *devices[], int cnt,
+static int dmar_pci_device_match(struct pci_dev __rcu *devices[], int cnt,
struct pci_dev *dev)
{
int index;
@@ -431,11 +434,12 @@
struct dmar_drhd_unit *
dmar_find_matched_drhd_unit(struct pci_dev *dev)
{
- struct dmar_drhd_unit *dmaru = NULL;
+ struct dmar_drhd_unit *dmaru;
struct acpi_dmar_hardware_unit *drhd;
dev = pci_physfn(dev);
+ rcu_read_lock();
for_each_drhd_unit(dmaru) {
drhd = container_of(dmaru->hdr,
struct acpi_dmar_hardware_unit,
@@ -443,14 +447,17 @@
if (dmaru->include_all &&
drhd->segment == pci_domain_nr(dev->bus))
- return dmaru;
+ goto out;
if (dmar_pci_device_match(dmaru->devices,
dmaru->devices_cnt, dev))
- return dmaru;
+ goto out;
}
+ dmaru = NULL;
+out:
+ rcu_read_unlock();
- return NULL;
+ return dmaru;
}
int __init dmar_dev_scope_init(void)