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[ Upstream commit399dbcadc0] There is no synchronization between different code paths in the ACPI battery driver that update its sysfs interface or its power supply class device interface. In some cases this results to functional failures due to race conditions. One example of this is when two ACPI notifications: - ACPI_BATTERY_NOTIFY_STATUS (0x80) - ACPI_BATTERY_NOTIFY_INFO (0x81) are triggered (by the platform firmware) in a row with a little delay in between after removing and reinserting a laptop battery. Both notifications cause acpi_battery_update() to be called and if the delay between them is sufficiently small, sysfs_add_battery() can be re-entered before battery->bat is set which leads to a duplicate sysfs entry error: sysfs: cannot create duplicate filename '/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0A:00/power_supply/BAT1' CPU: 1 UID: 0 PID: 185 Comm: kworker/1:4 Kdump: loaded Not tainted 6.12.38+deb13-amd64 #1 Debian 6.12.38-1 Hardware name: Gateway NV44 /SJV40-MV , BIOS V1.3121 04/08/2009 Workqueue: kacpi_notify acpi_os_execute_deferred Call Trace: <TASK> dump_stack_lvl+0x5d/0x80 sysfs_warn_dup.cold+0x17/0x23 sysfs_create_dir_ns+0xce/0xe0 kobject_add_internal+0xba/0x250 kobject_add+0x96/0xc0 ? get_device_parent+0xde/0x1e0 device_add+0xe2/0x870 __power_supply_register.part.0+0x20f/0x3f0 ? wake_up_q+0x4e/0x90 sysfs_add_battery+0xa4/0x1d0 [battery] acpi_battery_update+0x19e/0x290 [battery] acpi_battery_notify+0x50/0x120 [battery] acpi_ev_notify_dispatch+0x49/0x70 acpi_os_execute_deferred+0x1a/0x30 process_one_work+0x177/0x330 worker_thread+0x251/0x390 ? __pfx_worker_thread+0x10/0x10 kthread+0xd2/0x100 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x34/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> kobject: kobject_add_internal failed for BAT1 with -EEXIST, don't try to register things with the same name in the same directory. There are also other scenarios in which analogous issues may occur. Address this by using a common lock in all of the code paths leading to updates of driver interfaces: ACPI Notify () handler, system resume callback and post-resume notification, device addition and removal. This new lock replaces sysfs_lock that has been used only in sysfs_remove_battery() which now is going to be always called under the new lock, so it doesn't need any internal locking any more. Fixes:1066625155("ACPI: battery: Install Notify() handler directly") Closes: https://lore.kernel.org/linux-acpi/20250910142653.313360-1-luogf2025@163.com/ Reported-by: GuangFei Luo <luogf2025@163.com> Tested-by: GuangFei Luo <luogf2025@163.com> Cc: 6.6+ <stable@vger.kernel.org> # 6.6+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.