From: Matt Redfearn <matt.redfearn@imgtec.com>
Date: Fri, 4 Nov 2016 09:28:58 +0000 (+0000)
Subject: MIPS: SMP-CPS: Don't BUG if a CPU fails to start
X-Git-Tag: v4.11-rc1~135^2~114
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=5b0093f3a4acc7f393f102e7e064f70efc3375b9;p=linux.git

MIPS: SMP-CPS: Don't BUG if a CPU fails to start

If there is no online CPU within a core which could receive the IPI to
start another VP in that core, a BUG() is triggered. Instead print a
warning and gracefully handle the failure such that the system remains
usable, albeit without the requested secondary CPU.

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Qais Yousef <qsyousef@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14504/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
---

diff --git a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c
index 44339b470ef4..a2544c2394e4 100644
--- a/arch/mips/kernel/smp-cps.c
+++ b/arch/mips/kernel/smp-cps.c
@@ -326,7 +326,11 @@ static void cps_boot_secondary(int cpu, struct task_struct *idle)
 			if (cpu_online(remote))
 				break;
 		}
-		BUG_ON(remote >= NR_CPUS);
+		if (remote >= NR_CPUS) {
+			pr_crit("No online CPU in core %u to start CPU%d\n",
+				core, cpu);
+			goto out;
+		}
 
 		err = smp_call_function_single(remote, remote_vpe_boot,
 					       NULL, 1);