[PATCH 4.14 48/59] ACPI: scan: Rearrange memory allocation in acpi_device_add()

Greg Kroah-Hartman
2021-03-29T08:10:32Z

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

[ 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>
---
drivers/acpi/scan.c | 57 +++++++++++++++++++++------------------------
1 file changed, 26 insertions(+), 31 deletions(-)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index bd58f0743cfc..9ec463da9a50 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -622,12 +622,23 @@ 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;
@@ -653,38 +664,26 @@ 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);
@@ -719,13 +718,9 @@ 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;
}
--
2.30.1