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Message-ID: <20250913075648.698043-1-luogf2025@163.com>
Date: Sat, 13 Sep 2025 15:56:48 +0800
From: GuangFei Luo <luogf2025@....com>
To: rafael@...nel.org,
gregkh@...uxfoundation.org
Cc: dan.carpenter@...aro.org,
lenb@...nel.org,
linux-acpi@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org,
lkp@...el.com,
luogf2025@....com,
sre@...nel.org,
stable@...r.kernel.org
Subject: [PATCH v5] ACPI: battery: prevent sysfs_add_battery re-entry on rapid events
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)
Both notifications call acpi_battery_update(). Because the events
happen very close in time, sysfs_add_battery() can be re-entered
before battery->bat is set, causing a duplicate sysfs entry error.
This patch ensures that sysfs_add_battery() is not re-entered
when battery->bat is already non-NULL, preventing the duplicate
sysfs creation and stabilizing battery hotplug handling.
[ 476.117945] sysfs: cannot create duplicate filename '/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0A:00/power_supply/BAT1'
[ 476.118896] 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
[ 476.118903] Hardware name: Gateway NV44 /SJV40-MV , BIOS V1.3121 04/08/2009
[ 476.118906] Workqueue: kacpi_notify acpi_os_execute_deferred
[ 476.118917] Call Trace:
[ 476.118922] <TASK>
[ 476.118929] dump_stack_lvl+0x5d/0x80
[ 476.118938] sysfs_warn_dup.cold+0x17/0x23
[ 476.118943] sysfs_create_dir_ns+0xce/0xe0
[ 476.118952] kobject_add_internal+0xba/0x250
[ 476.118959] kobject_add+0x96/0xc0
[ 476.118964] ? get_device_parent+0xde/0x1e0
[ 476.118970] device_add+0xe2/0x870
[ 476.118975] __power_supply_register.part.0+0x20f/0x3f0
[ 476.118981] ? wake_up_q+0x4e/0x90
[ 476.118990] sysfs_add_battery+0xa4/0x1d0 [battery]
[ 476.118998] acpi_battery_update+0x19e/0x290 [battery]
[ 476.119002] acpi_battery_notify+0x50/0x120 [battery]
[ 476.119006] acpi_ev_notify_dispatch+0x49/0x70
[ 476.119012] acpi_os_execute_deferred+0x1a/0x30
[ 476.119015] process_one_work+0x177/0x330
[ 476.119022] worker_thread+0x251/0x390
[ 476.119026] ? __pfx_worker_thread+0x10/0x10
[ 476.119030] kthread+0xd2/0x100
[ 476.119033] ? __pfx_kthread+0x10/0x10
[ 476.119035] ret_from_fork+0x34/0x50
[ 476.119040] ? __pfx_kthread+0x10/0x10
[ 476.119042] ret_from_fork_asm+0x1a/0x30
[ 476.119049] </TASK>
[ 476.142552] kobject: kobject_add_internal failed for BAT1 with -EEXIST, don't try to register things with the same name in the same directory.
[ 476.415022] ata1.00: unexpected _GTF length (8)
[ 476.428076] sd 0:0:0:0: [sda] Starting disk
[ 476.835035] ata1.00: unexpected _GTF length (8)
[ 476.839720] ata1.00: configured for UDMA/133
[ 491.328831] sysfs: cannot create duplicate filename '/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0A:00/power_supply/BAT1'
[ 491.329720] 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
[ 491.329727] Hardware name: Gateway NV44 /SJV40-MV , BIOS V1.3121 04/08/2009
[ 491.329731] Workqueue: kacpi_notify acpi_os_execute_deferred
[ 491.329741] Call Trace:
[ 491.329745] <TASK>
[ 491.329751] dump_stack_lvl+0x5d/0x80
[ 491.329758] sysfs_warn_dup.cold+0x17/0x23
[ 491.329762] sysfs_create_dir_ns+0xce/0xe0
[ 491.329770] kobject_add_internal+0xba/0x250
[ 491.329775] kobject_add+0x96/0xc0
[ 491.329779] ? get_device_parent+0xde/0x1e0
[ 491.329784] device_add+0xe2/0x870
[ 491.329790] __power_supply_register.part.0+0x20f/0x3f0
[ 491.329797] sysfs_add_battery+0xa4/0x1d0 [battery]
[ 491.329805] acpi_battery_update+0x19e/0x290 [battery]
[ 491.329809] acpi_battery_notify+0x50/0x120 [battery]
[ 491.329812] acpi_ev_notify_dispatch+0x49/0x70
[ 491.329817] acpi_os_execute_deferred+0x1a/0x30
[ 491.329820] process_one_work+0x177/0x330
[ 491.329826] worker_thread+0x251/0x390
[ 491.329830] ? __pfx_worker_thread+0x10/0x10
[ 491.329833] kthread+0xd2/0x100
[ 491.329836] ? __pfx_kthread+0x10/0x10
[ 491.329838] ret_from_fork+0x34/0x50
[ 491.329842] ? __pfx_kthread+0x10/0x10
[ 491.329844] ret_from_fork_asm+0x1a/0x30
[ 491.329850] </TASK>
[ 491.329855] kobject: kobject_add_internal failed for BAT1 with -EEXIST, don't try to register things with the same name in the same directory.
Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/r/202509101620.yI0HZ5gT-lkp@intel.com/
Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
Closes: https://lore.kernel.org/r/202509101620.yI0HZ5gT-lkp@intel.com/
Fixes: 508df92d1f8d ("ACPI: battery: register power_supply subdevice only when battery is present")
Signed-off-by: GuangFei Luo <luogf2025@....com>
Cc: stable@...r.kernel.org
---
v5:
- Move changelog above the '---' line as per submission guidelines.
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@...el.com/
v2:
- Fix missing mutex_unlock in acpi_battery_update()
(Reported-by: kernel test robot)
v1:
- Initial patch to handle race when hotplugging battery, preventing
duplicate sysfs entries.
---
drivers/acpi/battery.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 6905b56bf3e4..20d68f3e881f 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -850,6 +850,10 @@ static void __exit battery_hook_exit(void)
static int sysfs_add_battery(struct acpi_battery *battery)
{
+ guard(mutex)(&battery->sysfs_lock);
+ if (battery->bat)
+ return 0;
+
struct power_supply_config psy_cfg = {
.drv_data = battery,
.attr_grp = acpi_battery_groups,
@@ -1026,11 +1030,9 @@ static int acpi_battery_update(struct acpi_battery *battery, bool resume)
return result;
acpi_battery_quirks(battery);
- if (!battery->bat) {
- result = sysfs_add_battery(battery);
- if (result)
- return result;
- }
+ result = sysfs_add_battery(battery);
+ if (result)
+ return result;
/*
* Wakeup the system if battery is critical low
@@ -1112,12 +1114,12 @@ static int battery_notify(struct notifier_block *nb,
result = acpi_battery_get_info(battery);
if (result)
return result;
-
- result = sysfs_add_battery(battery);
- if (result)
- return result;
}
+ result = sysfs_add_battery(battery);
+ if (result)
+ return result;
+
acpi_battery_init_alarm(battery);
acpi_battery_get_state(battery);
break;
--
2.43.0
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