linux-kernel - [tip:x86/urgent] x86/apic: Fix num_processors value in case of failure

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Date:   Wed, 7 Sep 2016 23:29:13 -0700
From:   tip-bot for Dou Liyang <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     torvalds@...ux-foundation.org, rientjes@...gle.com,
        douly.fnst@...fujitsu.com, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, peterz@...radead.org, hpa@...or.com,
        mingo@...nel.org
Subject: [tip:x86/urgent] x86/apic: Fix num_processors value in case of
 failure

Commit-ID:  c291b015158577be533dd5a959dfc09bab119eed
Gitweb:     http://git.kernel.org/tip/c291b015158577be533dd5a959dfc09bab119eed
Author:     Dou Liyang <douly.fnst@...fujitsu.com>
AuthorDate: Wed, 7 Sep 2016 10:21:33 +0800
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 8 Sep 2016 08:11:03 +0200

x86/apic: Fix num_processors value in case of failure

If the topology package map check of the APIC ID and the CPU is a failure,
we don't generate the processor info for that APIC ID yet we increase
disabled_cpus by one - which is buggy.

Only increase num_processors once we are sure we don't fail.

Signed-off-by: Dou Liyang <douly.fnst@...fujitsu.com>
Acked-by: David Rientjes <rientjes@...gle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/1473214893-16481-1-git-send-email-douly.fnst@cn.fujitsu.com
[ Rewrote the changelog. ]
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/apic/apic.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 50c95af..f3e9b2d 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2093,7 +2093,6 @@ int generic_processor_info(int apicid, int version)
 		return -EINVAL;
 	}
 
-	num_processors++;
 	if (apicid == boot_cpu_physical_apicid) {
 		/*
 		 * x86_bios_cpu_apicid is required to have processors listed
@@ -2116,10 +2115,13 @@ int generic_processor_info(int apicid, int version)
 
 		pr_warning("APIC: Package limit reached. Processor %d/0x%x ignored.\n",
 			   thiscpu, apicid);
+
 		disabled_cpus++;
 		return -ENOSPC;
 	}
 
+	num_processors++;
+
 	/*
 	 * Validate version
 	 */