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 44339b470ef44e598dc20acbfdfd840487503a31..a2544c2394e42331cceee8f0bbf5b538f36e24fb 100644 (file)
--- 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);