Re: [PATCH v3] ACPI: battery: prevent sysfs_add_battery re-entry on rapid events

On Fri, Sep 12, 2025 at 11:48:59PM +0800, GuangFei Luo wrote:

v3:

• Modified the earlier approach: since sysfs_add_battery() is invoked from multiple places, the most reliable way is to add the lock inside the function itself.
• sysfs_remove_battery() had a similar race issue in the past, which was fixed by adding a lock as well. Reference: https://lore.kernel.org/all/9c921c22a7f33397a6774d7fa076db9b6a0fd669

.1312318300.git.len.brown@intel.com/

v2:

• Fix missing mutex_unlock in acpi_battery_update() (Reported-by: kernel test robot)

v1: When removing and reinserting the laptop battery, ACPI can trigger two notifications in quick succession:

• ACPI_BATTERY_NOTIFY_STATUS (0x80)
• ACPI_BATTERY_NOTIFY_INFO (0x81)

Changelog should go below the --- line.

static int sysfs_add_battery(struct acpi_battery *battery) {

• mutex_lock(&battery->sysfs_lock);

Why not just use a guard() here? That would make the logic elsewhere much simpler.

thanks,

greg k-h