stop_machine: fix error code handling on multiple cpus
Using |= for updating a value which might be updated on several cpus
concurrently will not always work since we need to make sure that the
update happens atomically.
To fix this just use a write if the called function returns an error
code on a cpu. We end up writing the error code of an arbitrary cpu
if multiple ones fail but that should be sufficient.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 0e688c6..8aff79d 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -66,6 +66,7 @@
enum stopmachine_state curstate = STOPMACHINE_NONE;
struct stop_machine_data *smdata = &idle;
int cpu = smp_processor_id();
+ int err;
if (!active_cpus) {
if (cpu == first_cpu(cpu_online_map))
@@ -86,9 +87,11 @@
hard_irq_disable();
break;
case STOPMACHINE_RUN:
- /* |= allows error detection if functions on
- * multiple CPUs. */
- smdata->fnret |= smdata->fn(smdata->data);
+ /* On multiple CPUs only a single error code
+ * is needed to tell that something failed. */
+ err = smdata->fn(smdata->data);
+ if (err)
+ smdata->fnret = err;
break;
default:
break;
