PCI: shpchp: Rename duplicate slot name N as N-1, N-2, N-M...

Commit ef0ff95f136f0f2d035667af5d18b824609de320 (shpchp: fix slot name)
introduces the shpchp_slot_with_bus module parameter, which was intended
to help work around broken firmware that assigns the same name to multiple
slots.

Commit b3bd307c628af2f0a581c42d5d7e4bcdbbf64b6a (shpchp: add message about
shpchp_slot_with_bus option) tells the user to use the above parameter
in the event of a name collision.

This approach is sub-optimal because it requires too much work from
the user.

Instead, let's rename the slot on behalf of the user. If firmware
assigns the name N to multiple slots, then:

	The first registered slot is assigned N
	The second registered slot is assigned N-1
	The third registered slot is assigned N-2
	The Mth registered slot becomes N-M

In the event we overflow the slot->name parameter, we report an
error to the user.

This is a temporary fix until the entire PCI core can be reworked
such that individual drivers no longer have to manage their own
slot names.

Tested-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Acked-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 15 insertions, 19 deletions

diff --git a/drivers/pci/hotplug/shpchp_core.c b/drivers/pci/hotplug/shpchp_core.c
index a8cbd039b85b..cc38615395f1 100644
--- a/drivers/pci/hotplug/shpchp_core.c
+++ b/drivers/pci/hotplug/shpchp_core.c
@@ -39,7 +39,6 @@
 int shpchp_debug;
 int shpchp_poll_mode;
 int shpchp_poll_time;
-static int shpchp_slot_with_bus;
 struct workqueue_struct *shpchp_wq;
 
 #define DRIVER_VERSION  "0.4"
@@ -53,11 +52,9 @@ MODULE_LICENSE("GPL");
 module_param(shpchp_debug, bool, 0644);
 module_param(shpchp_poll_mode, bool, 0644);
 module_param(shpchp_poll_time, int, 0644);
-module_param(shpchp_slot_with_bus, bool, 0644);
 MODULE_PARM_DESC(shpchp_debug, "Debugging mode enabled or not");
 MODULE_PARM_DESC(shpchp_poll_mode, "Using polling mechanism for hot-plug events or not");
 MODULE_PARM_DESC(shpchp_poll_time, "Polling mechanism frequency, in seconds");
-MODULE_PARM_DESC(shpchp_slot_with_bus, "Use bus number in the slot name");
 
 #define SHPC_MODULE_NAME "shpchp"
 
@@ -99,23 +96,13 @@ static void release_slot(struct hotplug_slot *hotplug_slot)
         kfree(slot);
 }
 
-static void make_slot_name(struct slot *slot)
-{
-        if (shpchp_slot_with_bus)
-                snprintf(slot->hotplug_slot->name, SLOT_NAME_SIZE, "%04d_%04d",
-                         slot->bus, slot->number);
-        else
-                snprintf(slot->hotplug_slot->name, SLOT_NAME_SIZE, "%d",
-                         slot->number);
-}
-
 static int init_slots(struct controller *ctrl)
 {
         struct slot *slot;
         struct hotplug_slot *hotplug_slot;
         struct hotplug_slot_info *info;
         int retval = -ENOMEM;
-        int i;
+        int i, len, dup = 1;
 
         for (i = 0; i < ctrl->num_slots; i++) {
                 slot = kzalloc(sizeof(*slot), GFP_KERNEL);
@@ -146,7 +133,7 @@ static int init_slots(struct controller *ctrl)
                 /* register this slot with the hotplug pci core */
                 hotplug_slot->private = slot;
                 hotplug_slot->release = &release_slot;
-                make_slot_name(slot);
+                snprintf(slot->name, SLOT_NAME_SIZE, "%d", slot->number);
                 hotplug_slot->ops = &shpchp_hotplug_slot_ops;
 
                 get_power_status(hotplug_slot, &info->power_status);
@@ -157,14 +144,23 @@ static int init_slots(struct controller *ctrl)
                 dbg("Registering bus=%x dev=%x hp_slot=%x sun=%x "
                     "slot_device_offset=%x\n", slot->bus, slot->device,
                     slot->hp_slot, slot->number, ctrl->slot_device_offset);
+duplicate_name:
                 retval = pci_hp_register(slot->hotplug_slot,
                                 ctrl->pci_dev->subordinate, slot->device);
                 if (retval) {
+                        /*
+                         * If slot N already exists, we'll try to create
+                         * slot N-1, N-2 ... N-M, until we overflow.
+                         */
+                        if (retval == -EEXIST) {
+                                len = snprintf(slot->name, SLOT_NAME_SIZE,
+                                               "%d-%d", slot->number, dup++);
+                                if (len < SLOT_NAME_SIZE)
+                                        goto duplicate_name;
+                                else
+                                        err("duplicate slot name overflow\n");
+                        }
                         err("pci_hp_register failed with error %d\n", retval);
-                        if (retval == -EEXIST)
-                                err("Failed to register slot because of name "
-                                    "collision. Try \'shpchp_slot_with_bus\' "
-                                    "module option.\n");
                         goto error_info;
                 }