[PATCH -next] platform/x86: dell-smbios-wmi: fix missing unlock on error in dell_smbios_wmi_call()

[Wei Yongjun <weiyongjun1@xxxxxxxxxx>]

Add the missing unlock before return from function dell_smbios_wmi_call()
in the error handling case.

Fixes: 1a258e670434 ("platform/x86: dell-smbios-wmi: Add new WMI dispatcher driver")
Signed-off-by: Wei Yongjun <weiyongjun1@xxxxxxxxxx>
---
 drivers/platform/x86/dell-smbios-wmi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/dell-smbios-wmi.c b/drivers/platform/x86/dell-smbios-wmi.c
index 35c13815..04da5a7 100644
--- a/drivers/platform/x86/dell-smbios-wmi.c
+++ b/drivers/platform/x86/dell-smbios-wmi.c
@@ -91,8 +91,10 @@ int dell_smbios_wmi_call(struct calling_interface_buffer *buffer)
 
 	mutex_lock(&call_mutex);
 	priv = get_first_smbios_priv();
-	if (!priv)
+	if (!priv) {
+		mutex_unlock(&call_mutex);
 		return -ENODEV;
+	}
 
 	size = sizeof(struct calling_interface_buffer);
 	difference = priv->req_buf_size - sizeof(u64) - size;