Re: [PATCH v4] ACPI: battery: prevent sysfs_add_battery re-entry on rapid events

[Greg KH <gregkh@linuxfoundation.org>]

On Sat, Sep 13, 2025 at 03:19:25PM +0800, GuangFei Luo wrote:
> v4:
>   - Uses guard(mutex) for battery->sysfs_lock in sysfs_add_battery().
>   - Since sysfs_add_battery() now handles the battery->bat check with
>     proper locking,the extra if (!battery->bat) check at the call site
>     has become redundant.
> 
> 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:

Again, all of this goes below the --- line, not above it.