[RFC PATCH 6/6] pci: Protect is_busmaster using the state lock
This wraps pci_set_master() and pci_clear_master() with the pci_dev
state lock. The clearing of is_busmaster in pci_disable_device()
is already covered.
This also adds a comment explaining why is_busmaster must not be
checked in pci_set_master() due to how the power management code
uses it.
Signed-off-by: Benjamin Herrenschmidt
---
drivers/pci/pci.c | 9 +
include/linux/pci.h | 2 +-
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 68152de2b5a0..13d988d5b2a3 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4052,11 +4052,18 @@ void __weak pcibios_set_master(struct pci_dev *dev)
*
* Enables bus-mastering on the device and calls pcibios_set_master()
* to do the needed arch specific settings.
+ *
+ * Note: This must not check dev->is_busmaster because the power management
+ * code will call this in order to restore the config space to the
+ * state of is_busmaster, thus is_busmaster might be set but the
+ * config space bit cleared.
*/
void pci_set_master(struct pci_dev *dev)
{
+ pci_dev_state_lock(dev);
__pci_set_master(dev, true);
pcibios_set_master(dev);
+ pci_dev_state_unlock(dev);
}
EXPORT_SYMBOL(pci_set_master);
@@ -4066,7 +4073,9 @@ EXPORT_SYMBOL(pci_set_master);
*/
void pci_clear_master(struct pci_dev *dev)
{
+ pci_dev_state_lock(dev);
__pci_set_master(dev, false);
+ pci_dev_state_unlock(dev);
}
EXPORT_SYMBOL(pci_clear_master);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 0d4fc22df190..a5bac5b21454 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -375,7 +375,6 @@ struct pci_dev {
unsigned intmultifunction:1;/* Multi-function device */
unsigned intis_added:1;
- unsigned intis_busmaster:1; /* Is busmaster */
unsigned intno_msi:1; /* May not use MSI */
unsigned intno_64bit_msi:1; /* May only use 32-bit MSIs */
unsigned intblock_cfg_access:1; /* Config space access blocked
*/
@@ -450,6 +449,7 @@ struct pci_dev {
struct mutexstate_lock; /* Protect local state bits */
/* --- Fields below this line are protected by the state_lock mutex */
+ unsigned intis_busmaster:1; /* Is busmaster */
};
static inline void pci_dev_state_lock(struct pci_dev *dev)
--
2.17.1
[RFC PATCH 6/6] pci: Protect is_busmaster using the state lock
This wraps pci_set_master() and pci_clear_master() with the pci_dev
state lock. The clearing of is_busmaster in pci_disable_device()
is already covered.
This also adds a comment explaining why is_busmaster must not be
checked in pci_set_master() due to how the power management code
uses it.
Signed-off-by: Benjamin Herrenschmidt
---
drivers/pci/pci.c | 9 +
include/linux/pci.h | 2 +-
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 68152de2b5a0..13d988d5b2a3 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4052,11 +4052,18 @@ void __weak pcibios_set_master(struct pci_dev *dev)
*
* Enables bus-mastering on the device and calls pcibios_set_master()
* to do the needed arch specific settings.
+ *
+ * Note: This must not check dev->is_busmaster because the power management
+ * code will call this in order to restore the config space to the
+ * state of is_busmaster, thus is_busmaster might be set but the
+ * config space bit cleared.
*/
void pci_set_master(struct pci_dev *dev)
{
+ pci_dev_state_lock(dev);
__pci_set_master(dev, true);
pcibios_set_master(dev);
+ pci_dev_state_unlock(dev);
}
EXPORT_SYMBOL(pci_set_master);
@@ -4066,7 +4073,9 @@ EXPORT_SYMBOL(pci_set_master);
*/
void pci_clear_master(struct pci_dev *dev)
{
+ pci_dev_state_lock(dev);
__pci_set_master(dev, false);
+ pci_dev_state_unlock(dev);
}
EXPORT_SYMBOL(pci_clear_master);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 0d4fc22df190..a5bac5b21454 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -375,7 +375,6 @@ struct pci_dev {
unsigned intmultifunction:1;/* Multi-function device */
unsigned intis_added:1;
- unsigned intis_busmaster:1; /* Is busmaster */
unsigned intno_msi:1; /* May not use MSI */
unsigned intno_64bit_msi:1; /* May only use 32-bit MSIs */
unsigned intblock_cfg_access:1; /* Config space access blocked
*/
@@ -450,6 +449,7 @@ struct pci_dev {
struct mutexstate_lock; /* Protect local state bits */
/* --- Fields below this line are protected by the state_lock mutex */
+ unsigned intis_busmaster:1; /* Is busmaster */
};
static inline void pci_dev_state_lock(struct pci_dev *dev)
--
2.17.1
