This protects enable/disable operations using the state mutex to
avoid races with, for example, concurrent enables on a bridge.
The bus hierarchy is walked first before taking the lock to
avoid lock nesting (though it would be ok if we ensured that
we always nest them bottom-up, it is better to just avoid the
issue alltogether, especially as we might find cases where
we want to take it top-down later).
Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
---
drivers/pci/pci.c | 51 ++++++++++++++++++++++++++++++++---------------
1 file changed, 35 insertions(+), 16 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 62591c153999..68152de2b5a0 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1540,26 +1540,33 @@ static int do_pci_enable_device(struct pci_dev *dev,
int bars)
*/
int pci_reenable_device(struct pci_dev *dev)
{
+ int rc = 0;
+
+ pci_dev_state_lock(dev);
if (pci_is_enabled(dev))
- return do_pci_enable_device(dev, (1 << PCI_NUM_RESOURCES) - 1);
- return 0;
+ rc = do_pci_enable_device(dev, (1 << PCI_NUM_RESOURCES) - 1);
+ pci_dev_state_unlock(dev);
+ return rc;
}
EXPORT_SYMBOL(pci_reenable_device);
static void pci_enable_bridge(struct pci_dev *dev)
{
struct pci_dev *bridge;
- int retval;
+ int retval, enabled;
bridge = pci_upstream_bridge(dev);
if (bridge)
pci_enable_bridge(bridge);
- if (pci_is_enabled(dev)) {
- if (!dev->is_busmaster)
- pci_set_master(dev);
+ /* Already enabled ? */
+ pci_dev_state_lock(dev);
+ enabled = pci_is_enabled(dev);
+ if (enabled && !dev->is_busmaster)
+ pci_set_master(dev);
+ pci_dev_state_unlock(dev);
+ if (enabled)
return;
- }
retval = pci_enable_device(dev);
if (retval)
@@ -1571,9 +1578,16 @@ static void pci_enable_bridge(struct pci_dev *dev)
static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
{
struct pci_dev *bridge;
- int err;
+ int err = 0;
int i, bars = 0;
+ /* Handle upstream bridges first to avoid locking issues */
+ bridge = pci_upstream_bridge(dev);
+ if (bridge)
+ pci_enable_bridge(bridge);
+
+ pci_dev_state_lock(dev);
+
/*
* Power state could be unknown at this point, either due to a fresh
* boot or a device removal call. So get the current power state
@@ -1586,12 +1600,9 @@ static int pci_enable_device_flags(struct pci_dev *dev,
unsigned long flags)
dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK);
}
+ /* Already enabled ? */
if (atomic_inc_return(&dev->enable_cnt) > 1)
- return 0; /* already enabled */
-
- bridge = pci_upstream_bridge(dev);
- if (bridge)
- pci_enable_bridge(bridge);
+ goto bail;
/* only skip sriov related */
for (i = 0; i <= PCI_ROM_RESOURCE; i++)
@@ -1604,6 +1615,8 @@ static int pci_enable_device_flags(struct pci_dev *dev,
unsigned long flags)
err = do_pci_enable_device(dev, bars);
if (err < 0)
atomic_dec(&dev->enable_cnt);
+ bail:
+ pci_dev_state_unlock(dev);
return err;
}
@@ -1820,12 +1833,16 @@ static void do_pci_disable_device(struct pci_dev *dev)
* @dev: PCI device to disable
*
* NOTE: This function is a backend of PCI power management routines and is
- * not supposed to be called drivers.
+ * not supposed to be called drivers. It will keep enable_cnt and is_busmaster
+ * unmodified so that the resume code knows how to restore the corresponding
+ * command register bits.
*/
void pci_disable_enabled_device(struct pci_dev *dev)
{
+ pci_dev_state_lock(dev);
if (pci_is_enabled(dev))
do_pci_disable_device(dev);
+ pci_dev_state_unlock(dev);
}
/**
@@ -1849,12 +1866,14 @@ void pci_disable_device(struct pci_dev *dev)
dev_WARN_ONCE(&dev->dev, atomic_read(&dev->enable_cnt) <= 0,
"disabling already-disabled device");
+ pci_dev_state_lock(dev);
if (atomic_dec_return(&dev->enable_cnt) != 0)
- return;
+ goto bail;
do_pci_disable_device(dev);
-
dev->is_busmaster = 0;
+ bail:
+ pci_dev_state_unlock(dev);
}
EXPORT_SYMBOL(pci_disable_device);
--
2.17.1
