[PATCH 1/2] PCI: Device driver function reset notification

[Keith Busch <keith.busch@intel.com>]

A user can issue a pci function level reset to a device using sysfs entry
/sys/bus/pci/devices/.../reset. A kernel driver handling the pci device
might like to know this reset is about to occur and when the reset attempt
completes. This is so the driver has a chance to take appropriate device
specific actions; for example, it may need to quiesce before the reset,
and reinitialize the device after.

Signed-off-by: Keith Busch <keith.busch@intel.com>
---
 drivers/pci/pci.c   |   13 +++++++++++++
 include/linux/pci.h |    3 +++
 2 files changed, 16 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index fdbc294..cb24bbe 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3320,6 +3320,15 @@ static int pci_dev_reset(struct pci_dev *dev, int probe)
 
 	return rc;
 }
+
+static void pci_reset_notify(struct pci_dev *dev, bool prepare)
+{
+	const struct pci_error_handlers *err_handler =
+			dev->driver ? dev->driver->err_handler : NULL;
+	if (err_handler && err_handler->reset_notify)
+		err_handler->reset_notify(dev, prepare);
+}
+
 /**
  * __pci_reset_function - reset a PCI device function
  * @dev: PCI device to reset
@@ -3408,11 +3417,13 @@ int pci_reset_function(struct pci_dev *dev)
 	if (rc)
 		return rc;
 
+	pci_reset_notify(dev, true);
 	pci_dev_save_and_disable(dev);
 
 	rc = pci_dev_reset(dev, 0);
 
 	pci_dev_restore(dev);
+	pci_reset_notify(dev, false);
 
 	return rc;
 }
@@ -3432,6 +3443,7 @@ int pci_try_reset_function(struct pci_dev *dev)
 	if (rc)
 		return rc;
 
+	pci_reset_notify(dev, true);
 	pci_dev_save_and_disable(dev);
 
 	if (pci_dev_trylock(dev)) {
@@ -3441,6 +3453,7 @@ int pci_try_reset_function(struct pci_dev *dev)
 		rc = -EAGAIN;
 
 	pci_dev_restore(dev);
+	pci_reset_notify(dev, false);
 
 	return rc;
 }
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 33aa2ca..d82dd3f 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -603,6 +603,9 @@ struct pci_error_handlers {
 	/* PCI slot has been reset */
 	pci_ers_result_t (*slot_reset)(struct pci_dev *dev);
 
+	/* PCI function reset prepare or completed */
+	void (*reset_notify)(struct pci_dev *dev, bool prepare);
+
 	/* Device driver may resume normal operations */
 	void (*resume)(struct pci_dev *dev);
 };
-- 
1.7.10.4