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| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2008-10-22 10:00:26 -0500 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2008-10-22 10:00:26 +1100 |
| commit | 8163bcac779f62c6bf847caed9bce905db0693fb (patch) | |
| tree | 8fcf397c504fadbebecde09901aacef06b4551d8 /kernel/stop_machine.c | |
| parent | c9583e55fa2b08a230c549bd1e3c0bde6c50d9cc (diff) | |
| download | lwn-8163bcac779f62c6bf847caed9bce905db0693fb.tar.gz lwn-8163bcac779f62c6bf847caed9bce905db0693fb.zip | |
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>
Diffstat (limited to 'kernel/stop_machine.c')
| -rw-r--r-- | kernel/stop_machine.c | 9 |
1 files 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; |