linux-kernel - [PATCH] x86: Issue a warning if number of present CPUs > maxcpus and CONFIG

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Message-ID: <20140215150223.63bb52fb@hananiah.suse.cz>
Date:	Sat, 15 Feb 2014 15:02:23 +0100
From:	Petr Tesarik <ptesarik@...e.cz>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Borislav Petkov <bp@...en8.de>,
	Jan Beulich <jbeulich@...e.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] x86: Issue a warning if number of present CPUs > maxcpus
 and CONFIG_HOTPLUG=n

Note that the check against i (value passed as maxcpus, but at least 1)
is repeated further down, including the warning, but since possible is
already clamped to max_cpus at that time, it is never printed. In fact,
for the non-hotplug case, the warning about exceeding maxcpus is only
ever printed if "possible_cpus" was also specified on the command line.

I strongly believe that such limitation was unintentional.

I also changed the message slightly -- the kernel parameter name is
maxcpus, not max_cpus.

Signed-off-by: Petr Tesarik <ptesarik@...e.cz>
---
 arch/x86/kernel/smpboot.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index a32da80..376b6c6 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1226,9 +1226,6 @@ __init void prefill_possible_map(void)
 #ifdef CONFIG_HOTPLUG_CPU
 		if (setup_max_cpus)
 			possible += disabled_cpus;
-#else
-		if (possible > i)
-			possible = i;
 #endif
 	} else
 		possible = setup_possible_cpus;
@@ -1246,7 +1243,7 @@ __init void prefill_possible_map(void)
 	if (!setup_max_cpus)
 #endif
 	if (possible > i) {
-		pr_warn("%d Processors exceeds max_cpus limit of %u\n",
+		pr_warn("%d Processors exceeds maxcpus limit of %u\n",
 			possible, setup_max_cpus);
 		possible = i;
 	}
-- 
1.8.4.5
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