[PATCH v3 17/17] ACPI: handle re-enumeration, when acpi_devices might already exist

Bjorn Helgaas
2009-09-21T19:30:07Z

acpi_bus_scan() traverses the namespace to enumerate devices and uses
acpi_add_single_object() to create acpi_devices. When the platform
notifies us of a hot-plug event, we need to traverse part of the namespace
again to figure out what appeared or disappeared. (We don't yet call
acpi_bus_scan() during hot-plug, but I plan to do that in the future.)

This patch makes acpi_add_single_object() notice when we already have
an acpi_device, so we don't need to make a new one.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
---
drivers/acpi/scan.c | 19 +++++++++++--------
1 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 954bd01..2c4cac5 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1400,10 +1400,10 @@ static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl,
void *context, void **return_value)
{
struct acpi_bus_ops *ops = context;
- struct acpi_device *device = NULL;
- acpi_status status;
int type;
unsigned long long sta;
+ struct acpi_device *device;
+ acpi_status status;
int result;

result = acpi_bus_type_and_status(handle, &type, &sta);
@@ -1414,13 +1414,16 @@ static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl,
!(sta & ACPI_STA_DEVICE_FUNCTIONING))
return AE_CTRL_DEPTH;

- if (ops->acpi_op_add)
- status = acpi_add_single_object(&device, handle, type, sta,
- ops);
- else
- status = acpi_bus_get_device(handle, &device);
+ /*
+ * We may already have an acpi_device from a previous enumeration. If
+ * so, we needn't add it again, but we may still have to start it.
+ */
+ device = NULL;
+ acpi_bus_get_device(handle, &device);
+ if (ops->acpi_op_add && !device)
+ acpi_add_single_object(&device, handle, type, sta, ops);

- if (ACPI_FAILURE(status))
+ if (!device)
return AE_CTRL_DEPTH;

if (ops->acpi_op_start && !(ops->acpi_op_add)) {