PCI: Add pci_reset_function_locked()

The implementation of PCI workarounds may require that the device is reset
from its probe function.  This implies that the PCI device lock is already
held, and makes calling pci_reset_function() impossible (since it will
itself try to take that lock).

Add pci_reset_function_locked(), which is the equivalent of
pci_reset_function(), except that it requires the PCI device lock to be
already held by the caller.

Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
[bhelgaas: folded in fix for conflict with 52354b9d1f46 ("PCI: Remove
__pci_dev_reset() and pci_dev_reset()")]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org	# 4.11: 52354b9d1f46: PCI: Remove __pci_dev_reset() and pci_dev_reset()
Cc: stable@vger.kernel.org	# 4.11

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index af0cc3456dc1b48b1325c06c5edd2ca8cc22a640..b4b7eab2940024024c46ead23d6b1c415fa146f7 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4259,6 +4259,41 @@ int pci_reset_function(struct pci_dev *dev)
 }
 EXPORT_SYMBOL_GPL(pci_reset_function);
 
+/**
+ * pci_reset_function_locked - quiesce and reset a PCI device function
+ * @dev: PCI device to reset
+ *
+ * Some devices allow an individual function to be reset without affecting
+ * other functions in the same device.  The PCI device must be responsive
+ * to PCI config space in order to use this function.
+ *
+ * This function does not just reset the PCI portion of a device, but
+ * clears all the state associated with the device.  This function differs
+ * from __pci_reset_function() in that it saves and restores device state
+ * over the reset.  It also differs from pci_reset_function() in that it
+ * requires the PCI device lock to be held.
+ *
+ * Returns 0 if the device function was successfully reset or negative if the
+ * device doesn't support resetting a single function.
+ */
+int pci_reset_function_locked(struct pci_dev *dev)
+{
+       int rc;
+
+       rc = pci_probe_reset_function(dev);
+       if (rc)
+               return rc;
+
+       pci_dev_save_and_disable(dev);
+
+       rc = __pci_reset_function_locked(dev);
+
+       pci_dev_restore(dev);
+
+       return rc;
+}
+EXPORT_SYMBOL_GPL(pci_reset_function_locked);
+
 /**
  * pci_try_reset_function - quiesce and reset a PCI device function
  * @dev: PCI device to reset

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 4869e66dd659a6bc8fe4ad90df2ed9d3ff98ccac..a75c136738529db410baf870f3baafc6e178a5a0 100644 (file)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1067,6 +1067,7 @@ void pcie_flr(struct pci_dev *dev);
 int __pci_reset_function(struct pci_dev *dev);
 int __pci_reset_function_locked(struct pci_dev *dev);
 int pci_reset_function(struct pci_dev *dev);
+int pci_reset_function_locked(struct pci_dev *dev);
 int pci_try_reset_function(struct pci_dev *dev);
 int pci_probe_reset_slot(struct pci_slot *slot);
 int pci_reset_slot(struct pci_slot *slot);