[PATCH] PCI: Fix bus error reset when CONFIG_SYSFS not set

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

The pci slot component is not compiled if the kernel config does not
set CONFIG_SYSFS, but a previous commit used a lock symbol from there
without considering when it isn't defined.

This patch fixes that by moving the mutex definition to a context outside
CONFIG_SYSFS. This also made it obvious the implementation missed going
to the fallback when there were no bus slots, so this is also fixed.

Fixes: 131b0ca2c7b263fd ("PCI/ERR: Use slot reset if available")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Keith Busch <keith.busch@intel.com>
---
 drivers/pci/pci.c  | 24 ++++++++++++++----------
 drivers/pci/slot.c |  1 -
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 2b4117011313..f6104a551b60 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -35,6 +35,8 @@
 #include <linux/aer.h>
 #include "pci.h"
 
+DEFINE_MUTEX(pci_slot_mutex);
+
 const char *pci_power_names[] = {
 	"error", "D0", "D1", "D2", "D3hot", "D3cold", "unknown",
 };
@@ -5201,21 +5203,23 @@ static int pci_bus_reset(struct pci_bus *bus, int probe)
 int pci_bus_error_reset(struct pci_dev *bridge)
 {
 	struct pci_bus *bus = bridge->subordinate;
+	struct pci_slot *slot;
 
 	if (!bus)
 		return -ENOTTY;
 
 	mutex_lock(&pci_slot_mutex);
-	if (!list_empty(&bus->slots)) {
-		struct pci_slot *slot;
-
-		list_for_each_entry(slot, &bus->slots, list)
-			if (pci_probe_reset_slot(slot))
-				goto bus_reset;
-		list_for_each_entry(slot, &bus->slots, list)
-			if (pci_slot_reset(slot, 0))
-				goto bus_reset;
-	}
+	if (list_empty(&bus->slots))
+		goto bus_reset;
+
+	list_for_each_entry(slot, &bus->slots, list)
+		if (pci_probe_reset_slot(slot))
+			goto bus_reset;
+
+	list_for_each_entry(slot, &bus->slots, list)
+		if (pci_slot_reset(slot, 0))
+			goto bus_reset;
+
 	mutex_unlock(&pci_slot_mutex);
 	return 0;
 bus_reset:
diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c
index 3da03fcc6fbf..c46d5e1ff536 100644
--- a/drivers/pci/slot.c
+++ b/drivers/pci/slot.c
@@ -14,7 +14,6 @@
 
 struct kset *pci_slots_kset;
 EXPORT_SYMBOL_GPL(pci_slots_kset);
-DEFINE_MUTEX(pci_slot_mutex);
 
 static ssize_t pci_slot_attr_show(struct kobject *kobj,
 					struct attribute *attr, char *buf)
-- 
2.14.4