On Fri, Mar 19, 2021 at 8:21 PM Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
>
> The decrementation of acpi_device_bus_id->instance_no
> in acpi_device_del() is incorrect, because it may cause
> a duplicate instance number to be allocated next time
> a device with the same acpi_device_bus_id is added.
>
> Replace above mentioned approach by using IDA framework.
>
> Fixes: e49bd2dd5a50 ("ACPI: use PNPID:instance_no as bus_id of ACPI device")
> Fixes: ca9dc8d42b30 ("ACPI / scan: Fix acpi_bus_id_list bookkeeping")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> ---
> v3: rewrote commit message once again as proposed by Rafael in v1
> drivers/acpi/internal.h | 4 +++-
> drivers/acpi/scan.c | 32 +++++++++++++++++++++++++++-----
> include/acpi/acpi_bus.h | 1 +
> 3 files changed, 31 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> index e6a5d997241c..417eb768d710 100644
> --- a/drivers/acpi/internal.h
> +++ b/drivers/acpi/internal.h
> @@ -9,6 +9,8 @@
> #ifndef _ACPI_INTERNAL_H_
> #define _ACPI_INTERNAL_H_
>
> +#include <linux/idr.h>
> +
> #define PREFIX "ACPI: "
>
> int early_acpi_osi_init(void);
> @@ -98,7 +100,7 @@ extern struct list_head acpi_bus_id_list;
>
> struct acpi_device_bus_id {
> const char *bus_id;
> - unsigned int instance_no;
> + struct ida instance_ida;
> struct list_head node;
> };
>
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index a184529d8fa4..4b445b169ad4 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -479,9 +479,8 @@ static void acpi_device_del(struct acpi_device *device)
> 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))) {
> - if (acpi_device_bus_id->instance_no > 0)
> - acpi_device_bus_id->instance_no--;
> - else {
> + ida_simple_remove(&acpi_device_bus_id->instance_ida, device->pnp.instance_no);
> + if (ida_is_empty(&acpi_device_bus_id->instance_ida)) {
> list_del(&acpi_device_bus_id->node);
> kfree_const(acpi_device_bus_id->bus_id);
> kfree(acpi_device_bus_id);
> @@ -631,6 +630,20 @@ static struct acpi_device_bus_id *acpi_device_bus_id_match(const char *dev_id)
> return NULL;
> }
>
> +static int acpi_device_set_name(struct acpi_device *device,
> + struct acpi_device_bus_id *acpi_device_bus_id)
> +{
> + int result;
> +
> + result = ida_simple_get(&acpi_device_bus_id->instance_ida, 0, 255, GFP_KERNEL);
This is ida_alloc_range(ida, start, (end) - 1, gfp), so I think it
should be 256 above, instead of 255.
While at it, though, there can be more than 256 CPU devices easily on
contemporary systems, so I would use a greater number here. Maybe
4096 and define a symbol for it?
