[RFT 5/7] firmware: ensure the firmware cache is not used on incompatible calls

["Luis R. Rodriguez" <mcgrof@kernel.org>]

request_firmware_into_buf() explicitly disables the firmware cache,
meanwhile the firmware cache cannot be used when request_firmware_nowait()
is used without the uevent. Enforce a sanity check for this to avoid future
issues undocumented behaviours should misuses of the firmware cache
happen later.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 drivers/base/firmware_loader.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/base/firmware_loader.c b/drivers/base/firmware_loader.c
index 5f3d44d0bfe0..99c540164074 100644
--- a/drivers/base/firmware_loader.c
+++ b/drivers/base/firmware_loader.c
@@ -431,6 +431,11 @@ static int fw_add_devm_name(struct device *dev, const char *name)
 	return 0;
 }
 #else
+static bool fw_cache_is_setup(struct device *dev, const char *name)
+{
+	return false;
+}
+
 static int fw_add_devm_name(struct device *dev, const char *name)
 {
 	return 0;
@@ -672,6 +677,9 @@ request_firmware_into_buf(const struct firmware **firmware_p, const char *name,
 {
 	int ret;
 
+	if (fw_cache_is_setup(device, name))
+		return -EOPNOTSUPP;
+
 	__module_get(THIS_MODULE);
 	ret = _request_firmware(firmware_p, name, device, buf, size,
 				FW_OPT_UEVENT | FW_OPT_NOCACHE);
@@ -769,6 +777,9 @@ request_firmware_nowait(
 	fw_work->opt_flags = FW_OPT_NOWAIT |
 		(uevent ? FW_OPT_UEVENT : FW_OPT_USERHELPER);
 
+	if (!uevent && fw_cache_is_setup(device, name))
+		return -EOPNOTSUPP;
+
 	if (!try_module_get(module)) {
 		kfree_const(fw_work->name);
 		kfree(fw_work);
-- 
2.16.2