From: Vincent Donnefort vdonnefort@google.com
[ Upstream commit 6f855b39e4602b6b42a8e5cbcfefb8a1b8b5f0be ]
The DYING/STARTING callbacks are not expected to fail. However, as reported by Derek, buggy drivers such as tboot are still free to return errors within those sections, which halts the hot(un)plug and leaves the CPU in an unrecoverable state.
As there is no rollback possible, only log the failures and proceed with the following steps.
This restores the hotplug behaviour prior to commit 453e41085183 ("cpu/hotplug: Add cpuhp_invoke_callback_range()")
Fixes: 453e41085183 ("cpu/hotplug: Add cpuhp_invoke_callback_range()") Reported-by: Derek Dolney z23@posteo.net Signed-off-by: Vincent Donnefort vdonnefort@google.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Derek Dolney z23@posteo.net Reviewed-by: Valentin Schneider vschneid@redhat.com Link: https://bugzilla.kernel.org/show_bug.cgi?id=215867 Link: https://lore.kernel.org/r/20220927101259.1149636-1-vdonnefort@google.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/cpu.c | 56 +++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 40 insertions(+), 16 deletions(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c index e08d207011dd..393114c10c28 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -662,21 +662,51 @@ static bool cpuhp_next_state(bool bringup, return true; }
-static int cpuhp_invoke_callback_range(bool bringup, - unsigned int cpu, - struct cpuhp_cpu_state *st, - enum cpuhp_state target) +static int __cpuhp_invoke_callback_range(bool bringup, + unsigned int cpu, + struct cpuhp_cpu_state *st, + enum cpuhp_state target, + bool nofail) { enum cpuhp_state state; - int err = 0; + int ret = 0;
while (cpuhp_next_state(bringup, &state, st, target)) { + int err; + err = cpuhp_invoke_callback(cpu, state, bringup, NULL, NULL); - if (err) + if (!err) + continue; + + if (nofail) { + pr_warn("CPU %u %s state %s (%d) failed (%d)\n", + cpu, bringup ? "UP" : "DOWN", + cpuhp_get_step(st->state)->name, + st->state, err); + ret = -1; + } else { + ret = err; break; + } }
- return err; + return ret; +} + +static inline int cpuhp_invoke_callback_range(bool bringup, + unsigned int cpu, + struct cpuhp_cpu_state *st, + enum cpuhp_state target) +{ + return __cpuhp_invoke_callback_range(bringup, cpu, st, target, false); +} + +static inline void cpuhp_invoke_callback_range_nofail(bool bringup, + unsigned int cpu, + struct cpuhp_cpu_state *st, + enum cpuhp_state target) +{ + __cpuhp_invoke_callback_range(bringup, cpu, st, target, true); }
static inline bool can_rollback_cpu(struct cpuhp_cpu_state *st) @@ -994,7 +1024,6 @@ static int take_cpu_down(void *_param) struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE); int err, cpu = smp_processor_id(); - int ret;
/* Ensure this CPU doesn't handle any more interrupts. */ err = __cpu_disable(); @@ -1007,13 +1036,10 @@ static int take_cpu_down(void *_param) */ WARN_ON(st->state != (CPUHP_TEARDOWN_CPU - 1));
- /* Invoke the former CPU_DYING callbacks */ - ret = cpuhp_invoke_callback_range(false, cpu, st, target); - /* - * DYING must not fail! + * Invoke the former CPU_DYING callbacks. DYING must not fail! */ - WARN_ON_ONCE(ret); + cpuhp_invoke_callback_range_nofail(false, cpu, st, target);
/* Give up timekeeping duties */ tick_handover_do_timer(); @@ -1285,16 +1311,14 @@ void notify_cpu_starting(unsigned int cpu) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE); - int ret;
rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */ cpumask_set_cpu(cpu, &cpus_booted_once_mask); - ret = cpuhp_invoke_callback_range(true, cpu, st, target);
/* * STARTING must not fail! */ - WARN_ON_ONCE(ret); + cpuhp_invoke_callback_range_nofail(true, cpu, st, target); }
/*