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platform/x86: dell-smbios-wmi: Replace global list with single item

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There can only exist a single instance of the dell-smbios-wmi driver
at the same time because of naming conflicts with the character
device ("wmi/dell-smbios"). Having a global list for all instances
thus makes no sense.

Replace the global list with a single item used by the character
device. This simplifies the driver and allows us to mark it as
being multi-instance safe.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://patch.msgid.link/20260720131921.368000-4-W_Armin@gmx.de
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
This commit is contained in:
Armin Wolf 2026-07-20 15:19:21 +02:00 committed by Ilpo Järvinen
parent 08d31d42b0
commit b844001890
No known key found for this signature in database
GPG Key ID: 59AC4F6153E5CE31
1 changed files with 31 additions and 37 deletions
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68
drivers/platform/x86/dell/dell-smbios-wmi.c
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@ -10,7 +10,6 @@
#include <linux/device.h>
#include <linux/dmi.h>
#include <linux/fs.h>
#include <linux/list.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mutex.h>
@ -34,22 +33,14 @@ struct misc_bios_flags_structure {
struct wmi_smbios_priv {
struct mutex call_lock; /* Protects the content of the SMBIOS buffer */
struct dell_wmi_smbios_buffer *buf;
struct list_head list;
struct wmi_device *wdev;
struct device *child;
u64 req_buf_size;
struct miscdevice char_dev;
};
static DECLARE_RWSEM(list_lock); /* Protects access to wmi_list */
static LIST_HEAD(wmi_list);
static inline struct wmi_smbios_priv *get_first_smbios_priv(void)
{
return list_first_entry_or_null(&wmi_list,
struct wmi_smbios_priv,
list);
}
static DECLARE_RWSEM(chardev_lock); /* Protects chardev_priv */
static struct wmi_smbios_priv *chardev_priv;
static int run_smbios_call(struct wmi_device *wdev)
{
@ -106,16 +97,13 @@ static int dell_smbios_wmi_call(struct device *dev, struct calling_interface_buf
static ssize_t dell_smbios_wmi_read(struct file *filp, char __user *buffer, size_t length,
loff_t *offset)
{
struct wmi_smbios_priv *priv;
guard(rwsem_read)(&chardev_lock);
guard(rwsem_read)(&list_lock);
priv = get_first_smbios_priv();
if (!priv)
if (!chardev_priv)
return -ENODEV;
return simple_read_from_buffer(buffer, length, offset, &priv->req_buf_size,
sizeof(priv->req_buf_size));
return simple_read_from_buffer(buffer, length, offset, &chardev_priv->req_buf_size,
sizeof(chardev_priv->req_buf_size));
}
static long dell_smbios_wmi_do_ioctl(struct wmi_smbios_priv *priv,
@ -159,20 +147,18 @@ static long dell_smbios_wmi_do_ioctl(struct wmi_smbios_priv *priv,
static long dell_smbios_wmi_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct dell_wmi_smbios_buffer __user *input = (struct dell_wmi_smbios_buffer __user *)arg;
struct wmi_smbios_priv *priv;
if (cmd != DELL_WMI_SMBIOS_CMD)
return -ENOIOCTLCMD;
guard(rwsem_read)(&list_lock);
guard(rwsem_read)(&chardev_lock);
priv = get_first_smbios_priv();
if (!priv)
if (!chardev_priv)
return -ENODEV;
guard(mutex)(&priv->call_lock);
guard(mutex)(&chardev_priv->call_lock);
return dell_smbios_wmi_do_ioctl(priv, input);
return dell_smbios_wmi_do_ioctl(chardev_priv, input);
}
static const struct file_operations dell_smbios_wmi_fops = {
@ -189,10 +175,29 @@ static void dell_smbios_wmi_unregister_chardev(void *data)
misc_deregister(char_dev);
}
static void dell_smbios_wmi_clear_chardev(void *data)
{
guard(rwsem_write)(&chardev_lock);
chardev_priv = NULL;
}
static int dell_smbios_wmi_register_chardev(struct wmi_smbios_priv *priv)
{
int ret;
scoped_guard(rwsem_write, &chardev_lock) {
/* We can only have a single chardev at a time */
if (chardev_priv)
return -EBUSY;
chardev_priv = priv;
}
ret = devm_add_action_or_reset(&priv->wdev->dev, dell_smbios_wmi_clear_chardev, NULL);
if (ret < 0)
return ret;
priv->char_dev.minor = MISC_DYNAMIC_MINOR;
priv->char_dev.name = "wmi/dell-smbios";
priv->char_dev.fops = &dell_smbios_wmi_fops;
@ -256,24 +261,12 @@ static int dell_smbios_wmi_probe(struct wmi_device *wdev, const void *context)
if (ret)
return ret;
ret = dell_smbios_register_device(&wdev->dev, 1, &dell_smbios_wmi_call);
if (ret)
return ret;
guard(rwsem_write)(&list_lock);
list_add_tail(&priv->list, &wmi_list);
return 0;
return dell_smbios_register_device(&wdev->dev, 1, &dell_smbios_wmi_call);
}
static void dell_smbios_wmi_remove(struct wmi_device *wdev)
{
struct wmi_smbios_priv *priv = dev_get_drvdata(&wdev->dev);
dell_smbios_unregister_device(&wdev->dev);
guard(rwsem_write)(&list_lock);
list_del(&priv->list);
}
static const struct wmi_device_id dell_smbios_wmi_id_table[] = {
@ -311,6 +304,7 @@ static struct wmi_driver dell_smbios_wmi_driver = {
.probe = dell_smbios_wmi_probe,
.remove = dell_smbios_wmi_remove,
.id_table = dell_smbios_wmi_id_table,
.no_singleton = true,
};
int init_dell_smbios_wmi(void)