[PATCH 3.15 13/84] i8k: Fix non-SMP operation

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

3.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Guenter Roeck <linux@xxxxxxxxxxxx>

commit 6d827fbcc370ca259a2905309f64161ab7b10596 upstream.

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@xxxxxxxxx>
Tested-by: Jim Bos <jim876@xxxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Andreas Mohr <andi@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/char/i8k.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- 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;


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