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[PATCH v3] ACPI: battery: prevent sysfs_add_battery re-entry on rapid events

GuangFei Luo posted 1 patch 2 weeks, 6 days ago
There is a newer version of this series
drivers/acpi/battery.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
[PATCH v3] ACPI: battery: prevent sysfs_add_battery re-entry on rapid events
Posted by GuangFei Luo 2 weeks, 6 days ago 
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:

  - 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@intel.com>
Closes: https://lore.kernel.org/r/202509101620.yI0HZ5gT-lkp@intel.com/
Reported-by: Dan Carpenter <dan.carpenter@linaro.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@163.com>
Cc: stable@vger.kernel.org
---
 drivers/acpi/battery.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 6905b56bf3e4..f6d4a8b39a9c 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -850,6 +850,12 @@ static void __exit battery_hook_exit(void)
 
 static int sysfs_add_battery(struct acpi_battery *battery)
 {
+	mutex_lock(&battery->sysfs_lock);
+	if (battery->bat) {
+		mutex_unlock(&battery->sysfs_lock);
+		return 0;
+	}
+
 	struct power_supply_config psy_cfg = {
 		.drv_data = battery,
 		.attr_grp = acpi_battery_groups,
@@ -896,9 +902,11 @@ static int sysfs_add_battery(struct acpi_battery *battery)
 		int result = PTR_ERR(battery->bat);
 
 		battery->bat = NULL;
+		mutex_unlock(&battery->sysfs_lock);
 		return result;
 	}
 	battery_hook_add_battery(battery);
+	mutex_unlock(&battery->sysfs_lock);
 	return 0;
 }
 
@@ -1026,11 +1034,9 @@ 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
-- 
2.43.0
Re: [PATCH v3] ACPI: battery: prevent sysfs_add_battery re-entry on rapid events
Posted by Greg KH 2 weeks, 6 days ago 
On Fri, Sep 12, 2025 at 11:48:59PM +0800, GuangFei Luo wrote:
> 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:
> 
>   - ACPI_BATTERY_NOTIFY_STATUS (0x80)
>   - ACPI_BATTERY_NOTIFY_INFO   (0x81)

Changelog should go below the --- line.

>  static int sysfs_add_battery(struct acpi_battery *battery)
>  {
> +	mutex_lock(&battery->sysfs_lock);

Why not just use a guard() here?  That would make the logic elsewhere
much simpler.

thanks,

greg k-h
[PATCH v3] ACPI: battery: prevent sysfs_add_battery re-entry on rapid events
Posted by GuangFei Luo 2 weeks, 6 days ago 
Hi Greg,

Thanks for your review and suggestion.

I've updated sysfs_add_battery() to address your comment.
The locking is now applied explicitly inside the function
to prevent re-entry issues, while keeping the function
self-contained for all call sites.

Patch version: v3

Thanks,
GuangFei

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:

  - 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@intel.com>
Closes: https://lore.kernel.org/r/202509101620.yI0HZ5gT-lkp@intel.com/
Reported-by: Dan Carpenter <dan.carpenter@linaro.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@163.com>
Cc: stable@vger.kernel.org
---
 drivers/acpi/battery.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 6905b56bf3e4..f6d4a8b39a9c 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -850,6 +850,12 @@ static void __exit battery_hook_exit(void)
 
 static int sysfs_add_battery(struct acpi_battery *battery)
 {
+	mutex_lock(&battery->sysfs_lock);
+	if (battery->bat) {
+		mutex_unlock(&battery->sysfs_lock);
+		return 0;
+	}
+
 	struct power_supply_config psy_cfg = {
 		.drv_data = battery,
 		.attr_grp = acpi_battery_groups,
@@ -896,9 +902,11 @@ static int sysfs_add_battery(struct acpi_battery *battery)
 		int result = PTR_ERR(battery->bat);
 
 		battery->bat = NULL;
+		mutex_unlock(&battery->sysfs_lock);
 		return result;
 	}
 	battery_hook_add_battery(battery);
+	mutex_unlock(&battery->sysfs_lock);
 	return 0;
 }
 
@@ -1026,11 +1034,9 @@ 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
-- 
2.43.0
Re: [PATCH v3] ACPI: battery: prevent sysfs_add_battery re-entry on rapid events
Posted by Greg KH 2 weeks, 5 days ago 
On Sat, Sep 13, 2025 at 12:25:16AM +0800, GuangFei Luo wrote:
> Hi Greg,
> 
> Thanks for your review and suggestion.
> 
> I've updated sysfs_add_battery() to address your comment.
> The locking is now applied explicitly inside the function
> to prevent re-entry issues, while keeping the function
> self-contained for all call sites.
> 
> Patch version: v3
> 
> Thanks,
> GuangFei
> 
> 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:

Note, none of the above should be here in the changelog body, it should
be below the --- line.

> diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
> index 6905b56bf3e4..f6d4a8b39a9c 100644
> --- a/drivers/acpi/battery.c
> +++ b/drivers/acpi/battery.c
> @@ -850,6 +850,12 @@ static void __exit battery_hook_exit(void)
>  
>  static int sysfs_add_battery(struct acpi_battery *battery)
>  {
> +	mutex_lock(&battery->sysfs_lock);

Again, can you use guard() to make this logic simpler?  That would turn
this into a much smaller patch.

thanks,

greg k-h

Patchew 2.1-devel-b67e4c2

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