[PATCH 58/94] i8k: Fix non-SMP operation

[Sam Asadi <asadi.samuel@xxxxxxxxx>]

From: Guenter Roeck <linux@xxxxxxxxxxxx>

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>
Cc: stable@xxxxxxxxxxxxxxx # 3.14+
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Andreas Mohr <andi@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: sam-the-6 <asadi.samuel@xxxxxxxxx>
---
 drivers/char/i8k.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/char/i8k.c b/drivers/char/i8k.c
index d915707..93dcad0 100644
--- 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;
-- 
1.7.10.4

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