The attempt to prevent overwriting an active state resulted in a disaster which effectively disables all dynamically allocated hotplug states. Cleanup the mess. Fixes: dc280d936239 ("cpu/hotplug: Prevent overwriting of callbacks") Reported-by: Markus Trippelsdorf Reported-by: Boris Ostrovsky Signed-off-by: Thomas Gleixner --- kernel/cpu.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1471,6 +1471,7 @@ int __cpuhp_setup_state(enum cpuhp_state bool multi_instance) { int cpu, ret = 0; + bool dynstate; if (cpuhp_cb_check(state) || !name) return -EINVAL; @@ -1480,6 +1481,12 @@ int __cpuhp_setup_state(enum cpuhp_state ret = cpuhp_store_callbacks(state, name, startup, teardown, multi_instance); + dynstate = state == CPUHP_AP_ONLINE_DYN; + if (ret > 0 && dynstate) { + state = ret; + ret = 0; + } + if (ret || !invoke || !startup) goto out; @@ -1508,7 +1515,7 @@ int __cpuhp_setup_state(enum cpuhp_state * If the requested state is CPUHP_AP_ONLINE_DYN, return the * dynamically allocated state in case of success. */ - if (!ret && state == CPUHP_AP_ONLINE_DYN) + if (!ret && dynstate) return state; return ret; }