1 files changed, 49 insertions, 27 deletions

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index fdaa42aac7c6..2a581642c237 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -13,7 +13,7 @@
  * configuration space.
  */
 
-static DEFINE_RAW_SPINLOCK(pci_lock);
+DEFINE_RAW_SPINLOCK(pci_lock);
 
 /*
  *  Wrappers for all PCI configuration access functions.  They just check
@@ -127,20 +127,20 @@ EXPORT_SYMBOL(pci_write_vpd);
  * We have a bit per device to indicate it's blocked and a global wait queue
  * for callers to sleep on until devices are unblocked.
  */
-static DECLARE_WAIT_QUEUE_HEAD(pci_ucfg_wait);
+static DECLARE_WAIT_QUEUE_HEAD(pci_cfg_wait);
 
-static noinline void pci_wait_ucfg(struct pci_dev *dev)
+static noinline void pci_wait_cfg(struct pci_dev *dev)
 {
 	DECLARE_WAITQUEUE(wait, current);
 
-	__add_wait_queue(&pci_ucfg_wait, &wait);
+	__add_wait_queue(&pci_cfg_wait, &wait);
 	do {
 		set_current_state(TASK_UNINTERRUPTIBLE);
 		raw_spin_unlock_irq(&pci_lock);
 		schedule();
 		raw_spin_lock_irq(&pci_lock);
-	} while (dev->block_ucfg_access);
-	__remove_wait_queue(&pci_ucfg_wait, &wait);
+	} while (dev->block_cfg_access);
+	__remove_wait_queue(&pci_cfg_wait, &wait);
 }
 
 /* Returns 0 on success, negative values indicate error. */
@@ -153,7 +153,8 @@ int pci_user_read_config_##size						\
 	if (PCI_##size##_BAD)						\
 		return -EINVAL;						\
 	raw_spin_lock_irq(&pci_lock);				\
-	if (unlikely(dev->block_ucfg_access)) pci_wait_ucfg(dev);	\
+	if (unlikely(dev->block_cfg_access))				\
+		pci_wait_cfg(dev);					\
 	ret = dev->bus->ops->read(dev->bus, dev->devfn,			\
 					pos, sizeof(type), &data);	\
 	raw_spin_unlock_irq(&pci_lock);				\
@@ -172,7 +173,8 @@ int pci_user_write_config_##size					\
 	if (PCI_##size##_BAD)						\
 		return -EINVAL;						\
 	raw_spin_lock_irq(&pci_lock);				\
-	if (unlikely(dev->block_ucfg_access)) pci_wait_ucfg(dev);	\
+	if (unlikely(dev->block_cfg_access))				\
+		pci_wait_cfg(dev);					\
 	ret = dev->bus->ops->write(dev->bus, dev->devfn,		\
 					pos, sizeof(type), val);	\
 	raw_spin_unlock_irq(&pci_lock);				\
@@ -401,36 +403,56 @@ int pci_vpd_truncate(struct pci_dev *dev, size_t size)
 EXPORT_SYMBOL(pci_vpd_truncate);
 
 /**
- * pci_block_user_cfg_access - Block userspace PCI config reads/writes
+ * pci_cfg_access_lock - Lock PCI config reads/writes
  * @dev:	pci device struct
  *
- * When user access is blocked, any reads or writes to config space will
- * sleep until access is unblocked again.  We don't allow nesting of
- * block/unblock calls.
+ * When access is locked, any userspace reads or writes to config
+ * space and concurrent lock requests will sleep until access is
+ * allowed via pci_cfg_access_unlocked again.
  */
-void pci_block_user_cfg_access(struct pci_dev *dev)
+void pci_cfg_access_lock(struct pci_dev *dev)
+{
+	might_sleep();
+
+	raw_spin_lock_irq(&pci_lock);
+	if (dev->block_cfg_access)
+		pci_wait_cfg(dev);
+	dev->block_cfg_access = 1;
+	raw_spin_unlock_irq(&pci_lock);
+}
+EXPORT_SYMBOL_GPL(pci_cfg_access_lock);
+
+/**
+ * pci_cfg_access_trylock - try to lock PCI config reads/writes
+ * @dev:	pci device struct
+ *
+ * Same as pci_cfg_access_lock, but will return 0 if access is
+ * already locked, 1 otherwise. This function can be used from
+ * atomic contexts.
+ */
+bool pci_cfg_access_trylock(struct pci_dev *dev)
 {
 	unsigned long flags;
-	int was_blocked;
+	bool locked = true;
 
 	raw_spin_lock_irqsave(&pci_lock, flags);
-	was_blocked = dev->block_ucfg_access;
-	dev->block_ucfg_access = 1;
+	if (dev->block_cfg_access)
+		locked = false;
+	else
+		dev->block_cfg_access = 1;
 	raw_spin_unlock_irqrestore(&pci_lock, flags);
 
-	/* If we BUG() inside the pci_lock, we're guaranteed to hose
-	 * the machine */
-	BUG_ON(was_blocked);
+	return locked;
 }
-EXPORT_SYMBOL_GPL(pci_block_user_cfg_access);
+EXPORT_SYMBOL_GPL(pci_cfg_access_trylock);
 
 /**
- * pci_unblock_user_cfg_access - Unblock userspace PCI config reads/writes
+ * pci_cfg_access_unlock - Unlock PCI config reads/writes
  * @dev:	pci device struct
  *
- * This function allows userspace PCI config accesses to resume.
+ * This function allows PCI config accesses to resume.
  */
-void pci_unblock_user_cfg_access(struct pci_dev *dev)
+void pci_cfg_access_unlock(struct pci_dev *dev)
 {
 	unsigned long flags;
 
@@ -438,10 +460,10 @@ void pci_unblock_user_cfg_access(struct pci_dev *dev)
 
 	/* This indicates a problem in the caller, but we don't need
 	 * to kill them, unlike a double-block above. */
-	WARN_ON(!dev->block_ucfg_access);
+	WARN_ON(!dev->block_cfg_access);
 
-	dev->block_ucfg_access = 0;
-	wake_up_all(&pci_ucfg_wait);
+	dev->block_cfg_access = 0;
+	wake_up_all(&pci_cfg_wait);
 	raw_spin_unlock_irqrestore(&pci_lock, flags);
 }
-EXPORT_SYMBOL_GPL(pci_unblock_user_cfg_access);
+EXPORT_SYMBOL_GPL(pci_cfg_access_unlock);