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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 <dongli.zhang@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Qais Yousef <qais.yousef@arm.com>
Link: https://lore.kernel.org/r/20210409055316.1709-1-dongli.zhang@oracle.com
This commit is contained in:
Dongli Zhang 2021-04-08 22:53:16 -07:00 committed by Thomas Gleixner
parent 1782dc87b2
commit ebca71a8c9
1 changed files with 7 additions and 0 deletions
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7
kernel/cpu.c
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@ -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);