From ebca71a8c96f0af2ba482489ecc64d88979cd825 Mon Sep 17 00:00:00 2001 From: Dongli Zhang Date: Thu, 8 Apr 2021 22:53:16 -0700 Subject: cpu/hotplug: Add debug printks for hotplug callback failures CPU hotplug callbacks can fail and cause a rollback to the previous state. These failures are silent and therefore hard to debug. Add pr_debug() to the up and down paths which provide information about the error code, the CPU and the failed state. The debug printks can be enabled via kernel command line or sysfs. [ tglx: Adopt to current mainline, massage printk and changelog ] Signed-off-by: Dongli Zhang Signed-off-by: Thomas Gleixner Reviewed-by: Qais Yousef Link: https://lore.kernel.org/r/20210409055316.1709-1-dongli.zhang@oracle.com --- kernel/cpu.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'kernel/cpu.c') diff --git a/kernel/cpu.c b/kernel/cpu.c index 7ef28e1d5ecd..192e43a87407 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -692,6 +692,10 @@ static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, ret = cpuhp_invoke_callback_range(true, cpu, st, target); if (ret) { + pr_debug("CPU UP failed (%d) CPU %u state %s (%d)\n", + ret, cpu, cpuhp_get_step(st->state)->name, + st->state); + cpuhp_reset_state(st, prev_state); if (can_rollback_cpu(st)) WARN_ON(cpuhp_invoke_callback_range(false, cpu, st, @@ -1091,6 +1095,9 @@ static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, ret = cpuhp_invoke_callback_range(false, cpu, st, target); if (ret) { + pr_debug("CPU DOWN failed (%d) CPU %u state %s (%d)\n", + ret, cpu, cpuhp_get_step(st->state)->name, + st->state); cpuhp_reset_state(st, prev_state); -- cgit