i8k: Fix non-SMP operation

Commit f36fdb9f0266 (i8k: Force SMM to run on CPU 0) adds support
for multi-core CPUs to the driver. Unfortunately, that causes it
to fail loading if compiled without SMP support, at least on
32 bit kernels. Kernel log shows "i8k: unable to get SMM Dell
signature", and function i8k_smm is found to return -EINVAL.

Testing revealed that the culprit is the missing return value check
of set_cpus_allowed_ptr.

Fixes: f36fdb9f0266 (i8k: Force SMM to run on CPU 0)
Reported-by: Jim Bos <jim876@xs4all.nl>
Tested-by: Jim Bos <jim876@xs4all.nl>
Cc: stable@vger.kernel.org # 3.14+
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Cc: Andreas Mohr <andi@lisas.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/i8k.c b/drivers/char/i8k.c
index d915707..93dcad0 100644 (file)
--- a/drivers/char/i8k.c
+++ b/drivers/char/i8k.c
@@ -138,7 +138,9 @@ static int i8k_smm(struct smm_regs *regs)
        if (!alloc_cpumask_var(&old_mask, GFP_KERNEL))
                return -ENOMEM;
        cpumask_copy(old_mask, &current->cpus_allowed);
-       set_cpus_allowed_ptr(current, cpumask_of(0));
+       rc = set_cpus_allowed_ptr(current, cpumask_of(0));
+       if (rc)
+               goto out;
        if (smp_processor_id() != 0) {
                rc = -EBUSY;
                goto out;