powerpc/kdump: Fix race in kdump shutdown

[pandora-kernel.git] / arch / powerpc / kernel / crash.c

diff --git a/arch/powerpc/kernel/crash.c b/arch/powerpc/kernel/crash.c
index cca7c8f..8c066d6 100644 (file)
--- a/arch/powerpc/kernel/crash.c
+++ b/arch/powerpc/kernel/crash.c
@@ -162,6 +162,32 @@ static void crash_kexec_prepare_cpus(int cpu)
        /* Leave the IPI callback set */
 }
 
+/* wait for all the CPUs to hit real mode but timeout if they don't come in */
+static void crash_kexec_wait_realmode(int cpu)
+{
+       unsigned int msecs;
+       int i;
+
+       msecs = 10000;
+       for (i=0; i < NR_CPUS && msecs > 0; i++) {
+               if (i == cpu)
+                       continue;
+
+               while (paca[i].kexec_state < KEXEC_STATE_REAL_MODE) {
+                       barrier();
+                       if (!cpu_possible(i)) {
+                               break;
+                       }
+                       if (!cpu_online(i)) {
+                               break;
+                       }
+                       msecs--;
+                       mdelay(1);
+               }
+       }
+       mb();
+}
+
 /*
  * This function will be called by secondary cpus or by kexec cpu
  * if soft-reset is activated to stop some CPUs.
@@ -419,6 +445,7 @@ void default_machine_crash_shutdown(struct pt_regs *regs)
        crash_kexec_prepare_cpus(crashing_cpu);
        cpu_set(crashing_cpu, cpus_in_crash);
        crash_kexec_stop_spus();
+       crash_kexec_wait_realmode(crashing_cpu);
        if (ppc_md.kexec_cpu_down)
                ppc_md.kexec_cpu_down(1, 0);
 }