MIPS: smp: Make stop_this_cpu() actually stop the CPU

Since cpu_wait() enables interrupts upon return, CPUs which have
entered stop_this_cpu() may still end up handling interrupts.
This can lead to the softlockup detector firing on a panic or
restart/poweroff/halt.  Just disable interrupts and spin to ensure
nothing else runs on the CPU once it has entered stop_this_cpu().

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9601/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 2 insertions, 4 deletions

diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 1c0d8c50b7e1..5b020bda3e05 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -176,10 +176,8 @@ static void stop_this_cpu(void *dummy)
          * Remove this CPU:
          */
         set_cpu_online(smp_processor_id(), false);
-        for (;;) {
-                if (cpu_wait)
-                        (*cpu_wait)();          /* Wait if available. */
-        }
+        local_irq_disable();
+        while (1);
 }
 
 void smp_send_stop(void)