@@ -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);
@@ -375,7 +375,6 @@ struct pci_dev {
unsigned int multifunction:1; /* Multi-function device */
unsigned int is_added:1;
- unsigned int is_busmaster:1; /* Is busmaster */
unsigned int no_msi:1; /* May not use MSI */
unsigned int no_64bit_msi:1; /* May only use 32-bit MSIs */
unsigned int block_cfg_access:1; /* Config space access blocked */
@@ -450,6 +449,7 @@ struct pci_dev {
struct mutex state_lock; /* Protect local state bits */
/* --- Fields below this line are protected by the state_lock mutex */
+ unsigned int is_busmaster:1; /* Is busmaster */
};
static inline void pci_dev_state_lock(struct pci_dev *dev)
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 <benh@kernel.crashing.org> --- drivers/pci/pci.c | 9 +++++++++ include/linux/pci.h | 2 +- 2 files changed, 10 insertions(+), 1 deletion(-)