linux-kernel - [PATCH v2 3/3] kernel/smp: Tell the user we're bringing up secondary CPUs

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Date:   Wed, 26 Oct 2016 16:37:55 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     akpm@...l.org
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, peterz@...radead.org, jgross@...e.com,
        mgorman@...hsingularity.net, richard@....at, len.brown@...el.com,
        bp@...e.de, boris.ostrovsky@...cle.com, tim.c.chen@...ux.intel.com,
        ak@...ux.intel.com, jolsa@...hat.com, linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/3] kernel/smp: Tell the user we're bringing up secondary CPUs

Currently we don't print anything before starting to bring up secondary
CPUs. This can be confusing if it takes a long time to bring up the
secondaries, or if the kernel crashes while doing so and produces no
further output.

On x86 they work around this by detecting when the first secondary CPU
comes up and printing a message (see announce_cpu()). But doing it in
smp_init() is simpler and works for all arches.

Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Reviewed-by: Borislav Petkov <bp@...e.de>
---
 kernel/smp.c | 2 ++
 1 file changed, 2 insertions(+)

v2: Drop "smp:" from pr_info() now we have pr_fmt() defined.

diff --git a/kernel/smp.c b/kernel/smp.c
index 4323c5db7d26..77fcdb9f2775 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -555,6 +555,8 @@ void __init smp_init(void)
 	idle_threads_init();
 	cpuhp_threads_init();

+	pr_info("Bringing up secondary CPUs ...\n");
+
 	/* FIXME: This should be done in userspace --RR */
 	for_each_present_cpu(cpu) {
 		if (num_online_cpus() >= setup_max_cpus)
-- 
2.7.4