6.6-stable review patch. If anyone has any objections, please let me know.
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From: "Rafael J. Wysocki" rafael.j.wysocki@intel.com
[ Upstream commit 399dbcadc01ebf0035f325eaa8c264f8b5cd0a14 ]
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: 10666251554c ("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 --- drivers/acpi/battery.c | 43 +++++++++++++++++++++++++++++-------------- 1 file changed, 29 insertions(+), 14 deletions(-)
--- a/drivers/acpi/battery.c +++ b/drivers/acpi/battery.c @@ -94,7 +94,7 @@ enum {
struct acpi_battery { struct mutex lock; - struct mutex sysfs_lock; + struct mutex update_lock; struct power_supply *bat; struct power_supply_desc bat_desc; struct acpi_device *device; @@ -888,15 +888,12 @@ static int sysfs_add_battery(struct acpi
static void sysfs_remove_battery(struct acpi_battery *battery) { - mutex_lock(&battery->sysfs_lock); - if (!battery->bat) { - mutex_unlock(&battery->sysfs_lock); + if (!battery->bat) return; - } + battery_hook_remove_battery(battery); power_supply_unregister(battery->bat); battery->bat = NULL; - mutex_unlock(&battery->sysfs_lock); }
static void find_battery(const struct dmi_header *dm, void *private) @@ -1056,6 +1053,9 @@ static void acpi_battery_notify(acpi_han
if (!battery) return; + + guard(mutex)(&battery->update_lock); + old = battery->bat; /* * On Acer Aspire V5-573G notifications are sometimes triggered too @@ -1078,21 +1078,22 @@ static void acpi_battery_notify(acpi_han }
static int battery_notify(struct notifier_block *nb, - unsigned long mode, void *_unused) + unsigned long mode, void *_unused) { struct acpi_battery *battery = container_of(nb, struct acpi_battery, pm_nb); - int result;
- switch (mode) { - case PM_POST_HIBERNATION: - case PM_POST_SUSPEND: + if (mode == PM_POST_SUSPEND || mode == PM_POST_HIBERNATION) { + guard(mutex)(&battery->update_lock); + if (!acpi_battery_present(battery)) return 0;
if (battery->bat) { acpi_battery_refresh(battery); } else { + int result; + result = acpi_battery_get_info(battery); if (result) return result; @@ -1104,7 +1105,6 @@ static int battery_notify(struct notifie
acpi_battery_init_alarm(battery); acpi_battery_get_state(battery); - break; }
return 0; @@ -1182,6 +1182,8 @@ static int acpi_battery_update_retry(str { int retry, ret;
+ guard(mutex)(&battery->update_lock); + for (retry = 5; retry; retry--) { ret = acpi_battery_update(battery, false); if (!ret) @@ -1192,6 +1194,13 @@ static int acpi_battery_update_retry(str return ret; }
+static void sysfs_battery_cleanup(struct acpi_battery *battery) +{ + guard(mutex)(&battery->update_lock); + + sysfs_remove_battery(battery); +} + static int acpi_battery_add(struct acpi_device *device) { int result = 0; @@ -1214,7 +1223,7 @@ static int acpi_battery_add(struct acpi_ if (result) return result;
- result = devm_mutex_init(&device->dev, &battery->sysfs_lock); + result = devm_mutex_init(&device->dev, &battery->update_lock); if (result) return result;
@@ -1244,7 +1253,7 @@ fail_pm: device_init_wakeup(&device->dev, 0); unregister_pm_notifier(&battery->pm_nb); fail: - sysfs_remove_battery(battery); + sysfs_battery_cleanup(battery);
return result; } @@ -1263,6 +1272,9 @@ static void acpi_battery_remove(struct a
device_init_wakeup(&device->dev, 0); unregister_pm_notifier(&battery->pm_nb); + + guard(mutex)(&battery->update_lock); + sysfs_remove_battery(battery); }
@@ -1280,6 +1292,9 @@ static int acpi_battery_resume(struct de return -EINVAL;
battery->update_time = 0; + + guard(mutex)(&battery->update_lock); + acpi_battery_update(battery, true); return 0; }