firmware: ensure the firmware cache is not used on incompatible calls

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.

One of the reasons we want to enforce this is the firmware cache is
used for helping with suspend/resume, and if incompatible calls use it
they can stall suspend.
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/firmware_loader/main.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 +777,12 @@ 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)) {
+		kfree_const(fw_work->name);
+		kfree(fw_work);
+		return -EOPNOTSUPP;
+	}
+
 	if (!try_module_get(module)) {
 		kfree_const(fw_work->name);
 		kfree(fw_work);