From 8163bcac779f62c6bf847caed9bce905db0693fb Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 22 Oct 2008 10:00:26 -0500 Subject: 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 Signed-off-by: Rusty Russell --- kernel/stop_machine.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 0e688c6a1a63..8aff79d90ddc 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -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; -- cgit v1.2.3