ACPI: scan: Rearrange memory allocation in acpi_device_add()

[ Upstream commit c1013ff7a5472db637c56bb6237f8343398c03a7 ]

The upfront allocation of new_bus_id is done to avoid allocating
memory under acpi_device_lock, but it doesn't really help,
because (1) it leads to many unnecessary memory allocations for
_ADR devices, (2) kstrdup_const() is run under that lock anyway and
(3) it complicates the code.

Rearrange acpi_device_add() to allocate memory for a new struct
acpi_device_bus_id instance only when necessary, eliminate a redundant
local variable from it and reduce the number of labels in there.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index dca5cc4..2729269 100644 (file)
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -623,12 +623,23 @@ void acpi_bus_put_acpi_device(struct acpi_device *adev)
        put_device(&adev->dev);
 }
 
+static struct acpi_device_bus_id *acpi_device_bus_id_match(const char *dev_id)
+{
+       struct acpi_device_bus_id *acpi_device_bus_id;
+
+       /* Find suitable bus_id and instance number in acpi_bus_id_list. */
+       list_for_each_entry(acpi_device_bus_id, &acpi_bus_id_list, node) {
+               if (!strcmp(acpi_device_bus_id->bus_id, dev_id))
+                       return acpi_device_bus_id;
+       }
+       return NULL;
+}
+
 int acpi_device_add(struct acpi_device *device,
                    void (*release)(struct device *))
 {
+       struct acpi_device_bus_id *acpi_device_bus_id;
        int result;
-       struct acpi_device_bus_id *acpi_device_bus_id, *new_bus_id;
-       int found = 0;
 
        if (device->handle) {
                acpi_status status;
@@ -654,38 +665,26 @@ int acpi_device_add(struct acpi_device *device,
        INIT_LIST_HEAD(&device->del_list);
        mutex_init(&device->physical_node_lock);
 
-       new_bus_id = kzalloc(sizeof(struct acpi_device_bus_id), GFP_KERNEL);
-       if (!new_bus_id) {
-               pr_err(PREFIX "Memory allocation error\n");
-               result = -ENOMEM;
-               goto err_detach;
-       }
-
        mutex_lock(&acpi_device_lock);
-       /*
-        * Find suitable bus_id and instance number in acpi_bus_id_list
-        * If failed, create one and link it into acpi_bus_id_list
-        */
-       list_for_each_entry(acpi_device_bus_id, &acpi_bus_id_list, node) {
-               if (!strcmp(acpi_device_bus_id->bus_id,
-                           acpi_device_hid(device))) {
-                       acpi_device_bus_id->instance_no++;
-                       found = 1;
-                       kfree(new_bus_id);
-                       break;
+
+       acpi_device_bus_id = acpi_device_bus_id_match(acpi_device_hid(device));
+       if (acpi_device_bus_id) {
+               acpi_device_bus_id->instance_no++;
+       } else {
+               acpi_device_bus_id = kzalloc(sizeof(*acpi_device_bus_id),
+                                            GFP_KERNEL);
+               if (!acpi_device_bus_id) {
+                       result = -ENOMEM;
+                       goto err_unlock;
                }
-       }
-       if (!found) {
-               acpi_device_bus_id = new_bus_id;
                acpi_device_bus_id->bus_id =
                        kstrdup_const(acpi_device_hid(device), GFP_KERNEL);
                if (!acpi_device_bus_id->bus_id) {
-                       pr_err(PREFIX "Memory allocation error for bus id\n");
+                       kfree(acpi_device_bus_id);
                        result = -ENOMEM;
-                       goto err_free_new_bus_id;
+                       goto err_unlock;
                }
 
-               acpi_device_bus_id->instance_no = 0;
                list_add_tail(&acpi_device_bus_id->node, &acpi_bus_id_list);
        }
        dev_set_name(&device->dev, "%s:%02x", acpi_device_bus_id->bus_id, acpi_device_bus_id->instance_no);
@@ -720,13 +719,9 @@ int acpi_device_add(struct acpi_device *device,
                list_del(&device->node);
        list_del(&device->wakeup_list);
 
- err_free_new_bus_id:
-       if (!found)
-               kfree(new_bus_id);
-
+ err_unlock:
        mutex_unlock(&acpi_device_lock);
 
- err_detach:
        acpi_detach_data(device->handle, acpi_scan_drop_device);
        return result;
 }