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authorVincent Donnefort <vincent.donnefort@arm.com>2021-02-16 10:35:05 +0000
committerIngo Molnar <mingo@kernel.org>2021-03-06 12:40:22 +0100
commit62f250694092dd5fef9900dc3126f07110bf9d48 (patch)
tree8828fd231d7d4ed6052e20174732c2e73fb52273 /kernel/cpu.c
parent3ae70c251f344976428d1f6ee61ea7b4e170fec3 (diff)
downloadlinux-62f250694092dd5fef9900dc3126f07110bf9d48.tar.bz2
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
Diffstat (limited to 'kernel/cpu.c')
-rw-r--r--kernel/cpu.c19
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);