[Crash-utility] [PATCH v2 08/25] modify bt -c to hide offline cpus' data

bt -c will display the stack trace of the active task on specified cpus. This patch will hide offline cpus' data and print a message like "bt: CPU xx is offline" to indicate the hide(xx is the id of the offline cpu). The original output is like below: <cut> crash> bt -c 2,3 PID: 0 TASK: ffff88003f380040 CPU: 2 COMMAND: "swapper" #0 [ffff88003f3adf00] cpu_idle at ffffffff8100a00b PID: 22 TASK: ffff88003f3fb500 CPU: 3 COMMAND: "events/3" #0 [ffff880002387e90] crash_nmi_callback at ffffffff8102fee6 #1 [ffff880002387ea0] notifier_call_chain at ffffffff8152d515 #2 [ffff880002387ee0] atomic_notifier_call_chain at ffffffff8152d57a #3 [ffff880002387ef0] notify_die at ffffffff810a154e #4 [ffff880002387f20] do_nmi at ffffffff8152b1db #5 [ffff880002387f50] nmi at ffffffff8152aaa0 ... <cut> With data of offline cpu(cpu #2) hiden, the output is like below: <cut> crash> bt -c 2,3 bt: CPU 2 is OFFLINE. PID: 22 TASK: ffff88003f3fb500 CPU: 3 COMMAND: "events/3" #0 [ffff880002387e90] crash_nmi_callback at ffffffff8102fee6 #1 [ffff880002387ea0] notifier_call_chain at ffffffff8152d515 #2 [ffff880002387ee0] atomic_notifier_call_chain at ffffffff8152d57a #3 [ffff880002387ef0] notify_die at ffffffff810a154e #4 [ffff880002387f20] do_nmi at ffffffff8152b1db ... <cut> Signed-off-by: Qiao Nuohan <qiaonuohan(a)cn.fujitsu.com&gt; --- kernel.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel.c b/kernel.c index 8948c84..f5f98ca 100755 --- a/kernel.c +++ b/kernel.c @@ -2261,6 +2261,12 @@ cmd_bt(void) for (i = 0; i < kt->cpus; i++) { if (NUM_IN_BITMAP(cpus, i)) { + if (hide_offline_cpu(i)) { + error(INFO, "%sCPU %d is OFFLINE.\n", + subsequent++ ? "\n" : "", i); + continue; + } + if ((task = get_active_task(i))) tc = task_to_context(task); else -- 1.8.5.3