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Subject[PATCH 6/16][BUG] ACPI pci_slot: Fix slot removal path (Not for mainline!)
Current ACPI pci slot driver scans ACPI namespace and slot list on
pci_bus structure to find the pci_slot pointer. It is definitely
redundant. In addition, it scans slot list on pci_bus without holding
pci_bus_sem. This patch fixes those problems.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>

---
drivers/acpi/pci_slot.c | 104 +++++++++++++++++++++++++-----------------------
1 file changed, 55 insertions(+), 49 deletions(-)

Index: linux-2.6.25-rc6/drivers/acpi/pci_slot.c
===================================================================
--- linux-2.6.25-rc6.orig/drivers/acpi/pci_slot.c
+++ linux-2.6.25-rc6/drivers/acpi/pci_slot.c
@@ -55,9 +55,17 @@ ACPI_MODULE_NAME("pci_slot");
MY_NAME , ## arg); \
} while (0)

+struct acpi_pci_slot {
+ acpi_handle root_handle; /* handle of the root bridge */
+ struct pci_slot *pci_slot; /* corresponding pci_slot */
+ struct list_head list; /* node in the list of slots */
+};
+
static int acpi_pci_slot_add(acpi_handle handle);
static void acpi_pci_slot_remove(acpi_handle handle);

+static LIST_HEAD(slot_list);
+static DEFINE_MUTEX(slot_list_lock);
static struct acpi_pci_driver acpi_pci_slot_driver = {
.add = acpi_pci_slot_add,
.remove = acpi_pci_slot_remove,
@@ -105,34 +113,11 @@ out:
return retval;
}

-/*
- * unregister_slot
- *
- * Called once for each SxFy object in the namespace. Each call to
- * pci_destroy_slot decrements the refcount on the pci_slot, and
- * eventually calls kobject_unregister at the appropriate time.
- */
-static acpi_status
-unregister_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
-{
- int device;
- unsigned long sun;
- struct pci_slot *slot, *tmp;
- struct pci_bus *pci_bus = context;
-
- if (check_slot(handle, &device, &sun))
- return AE_OK;
-
- /* FIXME - Need pci_bus_sem to be held */
- list_for_each_entry_safe(slot, tmp, &pci_bus->slots, list) {
- if (slot->number == device) {
- pci_destroy_slot(slot);
- break;
- }
- }
-
- return AE_OK;
-}
+struct callback_args {
+ acpi_walk_callback user_function; /* only for walk_p2p_bridge */
+ struct pci_bus *pci_bus;
+ acpi_handle root_handle;
+};

/*
* register_slot
@@ -150,17 +135,33 @@ register_slot(acpi_handle handle, u32 lv
int device;
unsigned long sun;
char name[KOBJ_NAME_LEN];
-
+ struct acpi_pci_slot *slot;
struct pci_slot *pci_slot;
- struct pci_bus *pci_bus = context;
+ struct callback_args *parent_context = context;
+ struct pci_bus *pci_bus = parent_context->pci_bus;

if (check_slot(handle, &device, &sun))
return AE_OK;

+ slot = kmalloc(sizeof(*slot), GFP_KERNEL);
+ if (!slot) {
+ err("%s: cannot allocate memory\n", __FUNCTION__);
+ return AE_OK;
+ }
+
snprintf(name, sizeof(name), "%u", (u32)sun);
pci_slot = pci_create_slot(pci_bus, device, name);
- if (IS_ERR(pci_slot))
+ if (IS_ERR(pci_slot)) {
err("pci_create_slot returned %ld\n", PTR_ERR(pci_slot));
+ kfree(slot);
+ }
+
+ slot->root_handle = parent_context->root_handle;
+ slot->pci_slot = pci_slot;
+ INIT_LIST_HEAD(&slot->list);
+ mutex_lock(&slot_list_lock);
+ list_add(&slot->list, &slot_list);
+ mutex_unlock(&slot_list_lock);

dbg("pci_slot: %#lx, pci_bus: %x, device: %d, name: %s\n",
(uint64_t)pci_slot, pci_bus->number, device, name);
@@ -168,11 +169,6 @@ register_slot(acpi_handle handle, u32 lv
return AE_OK;
}

-struct p2p_bridge_context {
- acpi_walk_callback user_function;
- struct pci_bus *pci_bus;
-};
-
/*
* walk_p2p_bridge - discover and walk p2p bridges
* @handle: points to an acpi_pci_root
@@ -192,8 +188,8 @@ walk_p2p_bridge(acpi_handle handle, u32

struct pci_dev *dev;
struct pci_bus *pci_bus;
- struct p2p_bridge_context child_context;
- struct p2p_bridge_context *parent_context = context;
+ struct callback_args child_context;
+ struct callback_args *parent_context = context;

pci_bus = parent_context->pci_bus;
user_function = parent_context->user_function;
@@ -213,14 +209,16 @@ walk_p2p_bridge(acpi_handle handle, u32
if (!dev || !dev->subordinate)
goto out;

+ child_context.pci_bus = dev->subordinate;
+ child_context.user_function = user_function;
+ child_context.root_handle = parent_context->root_handle;
+
dbg("p2p bridge walk, pci_bus = %x\n", dev->subordinate->number);
status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
- user_function, dev->subordinate, NULL);
+ user_function, &child_context, NULL);
if (ACPI_FAILURE(status))
goto out;

- child_context.pci_bus = dev->subordinate;
- child_context.user_function = user_function;
status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
walk_p2p_bridge, &child_context, NULL);
out:
@@ -246,7 +244,7 @@ walk_root_bridge(acpi_handle handle, acp
acpi_status status;
acpi_handle dummy_handle;
struct pci_bus *pci_bus;
- struct p2p_bridge_context context;
+ struct callback_args context;

/* If the bridge doesn't have _STA, we assume it is always there */
status = acpi_get_handle(handle, "_STA", &dummy_handle);
@@ -271,14 +269,16 @@ walk_root_bridge(acpi_handle handle, acp
if (!pci_bus)
return 0;

+ context.pci_bus = pci_bus;
+ context.user_function = user_function;
+ context.root_handle = handle;
+
dbg("root bridge walk, pci_bus = %x\n", pci_bus->number);
status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
- user_function, pci_bus, NULL);
+ user_function, &context, NULL);
if (ACPI_FAILURE(status))
return status;

- context.pci_bus = pci_bus;
- context.user_function = user_function;
status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
walk_p2p_bridge, &context, NULL);
if (ACPI_FAILURE(status))
@@ -310,11 +310,17 @@ acpi_pci_slot_add(acpi_handle handle)
static void
acpi_pci_slot_remove(acpi_handle handle)
{
- acpi_status status;
+ struct acpi_pci_slot *slot, *tmp;

- status = walk_root_bridge(handle, unregister_slot);
- if (ACPI_FAILURE(status))
- err("%s: unregister_slot failure - %d\n", __func__, status);
+ mutex_lock(&slot_list_lock);
+ list_for_each_entry_safe(slot, tmp, &slot_list, list) {
+ if (slot->root_handle == handle) {
+ list_del(&slot->list);
+ pci_destroy_slot(slot->pci_slot);
+ kfree(slot);
+ }
+ }
+ mutex_unlock(&slot_list_lock);
}

#ifdef CONFIG_DMI



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