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stop_machine: fix error code handling on multiple cpus

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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>
This commit is contained in:
Heiko Carstens 2008-10-22 10:00:26 -05:00 committed by Rusty Russell
parent c9583e55fa
commit 8163bcac77
1 changed files with 6 additions and 3 deletions
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9
kernel/stop_machine.c
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@ -66,6 +66,7 @@ static void stop_cpu(struct work_struct *unused)
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 @@ static void stop_cpu(struct work_struct *unused)
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;