Messages in this thread Patch in this message |  | | From | Sumeet Pawnikar <> | | Subject | [PATCH] powercap: fix race condition in register_control_type | | Date | Sat, 6 Dec 2025 00:31:33 +0530 |
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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> --- drivers/powercap/powercap_sys.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/powercap/powercap_sys.c b/drivers/powercap/powercap_sys.c index 4112a0097338..bdc65e040d17 100644 --- a/drivers/powercap/powercap_sys.c +++ b/drivers/powercap/powercap_sys.c @@ -625,17 +625,22 @@ 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); -- 2.43.0
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