diff options
| author | Vincent Donnefort | 2021-02-16 10:35:05 +0000 |
|---|---|---|
| committer | Ingo Molnar | 2021-03-06 12:40:22 +0100 |
| commit | 62f250694092dd5fef9900dc3126f07110bf9d48 (patch) | |
| tree | 8828fd231d7d4ed6052e20174732c2e73fb52273 | |
| parent | 3ae70c251f344976428d1f6ee61ea7b4e170fec3 (diff) | |
cpu/hotplug: CPUHP_BRINGUP_CPU failure exception
The atomic states (between CPUHP_AP_IDLE_DEAD and CPUHP_AP_ONLINE) are
triggered by the CPUHP_BRINGUP_CPU step. If the latter fails, no atomic
state can be rolled back.
DEAD callbacks too can't fail and disallow recovery. As a consequence,
during hotunplug, the fail injection interface should prohibit all states
from CPUHP_BRINGUP_CPU to CPUHP_ONLINE.
Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210216103506.416286-3-vincent.donnefort@arm.com
| -rw-r--r-- | kernel/cpu.c | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 9121edf5759a..680ed8f427c0 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1045,9 +1045,13 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, * to do the further cleanups. */ ret = cpuhp_down_callbacks(cpu, st, target); - if (ret && st->state == CPUHP_TEARDOWN_CPU && st->state < prev_state) { - cpuhp_reset_state(st, prev_state); - __cpuhp_kick_ap(st); + if (ret && st->state < prev_state) { + if (st->state == CPUHP_TEARDOWN_CPU) { + cpuhp_reset_state(st, prev_state); + __cpuhp_kick_ap(st); + } else { + WARN(1, "DEAD callback error for CPU%d", cpu); + } } out: @@ -2222,6 +2226,15 @@ static ssize_t write_cpuhp_fail(struct device *dev, return -EINVAL; /* + * DEAD callbacks cannot fail... + * ... neither can CPUHP_BRINGUP_CPU during hotunplug. The latter + * triggering STARTING callbacks, a failure in this state would + * hinder rollback. + */ + if (fail <= CPUHP_BRINGUP_CPU && st->state > CPUHP_BRINGUP_CPU) + return -EINVAL; + + /* * Cannot fail anything that doesn't have callbacks. */ mutex_lock(&cpuhp_state_mutex); |