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powercap: fix race condition in register_control_type()

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[ Upstream commit 7bda1910c4bccd4b8d4726620bb3d6bbfb62286e ]

The device becomes visible to userspace via device_register()
even before it fully initialized by idr_init(). If userspace
or another thread tries to register a zone immediately after
device_register(), the control_type_valid() will fail because
the control_type is not yet in the list. The IDR is not yet
initialized, so this race condition causes zone registration
failure.

Move idr_init() and list addition before device_register()
fix the race condition.

Signed-off-by: Sumeet Pawnikar <sumeet4linux@gmail.com>
[ rjw: Subject adjustment, empty line added ]
Link: https://patch.msgid.link/20251205190216.5032-1-sumeet4linux@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Sumeet Pawnikar
2025-12-06 00:32:16 +05:30
committed by Greg Kroah-Hartman
parent 98676ee71f
commit e07dea55aa
1 changed files with 11 additions and 5 deletions
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16
drivers/powercap/powercap_sys.c
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@@ -625,17 +625,23 @@ struct powercap_control_type *powercap_register_control_type(
INIT_LIST_HEAD(&control_type->node);
control_type->dev.class = &powercap_class;
dev_set_name(&control_type->dev, "%s", name);
result = device_register(&control_type->dev);
if (result) {
put_device(&control_type->dev);
return ERR_PTR(result);
}
idr_init(&control_type->idr);
mutex_lock(&powercap_cntrl_list_lock);
list_add_tail(&control_type->node, &powercap_cntrl_list);
mutex_unlock(&powercap_cntrl_list_lock);
result = device_register(&control_type->dev);
if (result) {
mutex_lock(&powercap_cntrl_list_lock);
list_del(&control_type->node);
mutex_unlock(&powercap_cntrl_list_lock);
idr_destroy(&control_type->idr);
put_device(&control_type->dev);
return ERR_PTR(result);
}
return control_type;
}
EXPORT_SYMBOL_GPL(powercap_register_control_type);