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Message-ID: <20250907033925.223849-1-luogf2025@163.com>
Date: Sun,  7 Sep 2025 11:39:24 +0800
From: GuangFei Luo <luogf2025@....com>
To: "Rafael J . Wysocki" <rafael@...nel.org>
Cc: Len Brown <lenb@...nel.org>,
	linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	stable@...r.kernel.org,
	luogf2025@....com
Subject: [PATCH] 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.

Fixes: 508df92d1f8d ("ACPI: battery: register power_supply subdevice only when battery is present")
Signed-off-by: GuangFei Luo <luogf2025@....com>
---
 drivers/acpi/battery.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 6905b56bf3e4..3801fd34c969 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -1026,11 +1026,13 @@ static int acpi_battery_update(struct acpi_battery *battery, bool resume)
 		return result;
 	acpi_battery_quirks(battery);
 
+	mutex_lock(&battery->sysfs_lock);
 	if (!battery->bat) {
 		result = sysfs_add_battery(battery);
 		if (result)
 			return result;
 	}
+	mutex_unlock(&battery->sysfs_lock);
 
 	/*
 	 * Wakeup the system if battery is critical low
-- 
2.43.0


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