firmware: Introduce request_firmware_direct()

When CONFIG_FW_LOADER_USER_HELPER is set, request_firmware() falls
back to the usermode helper for loading via udev when the direct
loading fails.  But the recent udev takes way too long timeout (60
seconds) for non-existing firmware.  This is unacceptable for the
drivers like microcode loader where they load firmwares optionally,
i.e. it's no error even if no requested file exists.

This patch provides a new helper function, request_firmware_direct().
It behaves as same as request_firmware() except for that it doesn't
fall back to usermode helper but returns an error immediately if the
f/w can't be loaded directly in kernel.

Without CONFIG_FW_LOADER_USER_HELPER=y, request_firmware_direct() is
just an alias of request_firmware(), due to obvious reason.

Tested-by: Prarit Bhargava <prarit@redhat.com>
Acked-by: Ming Lei <ming.lei@canonical.com>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/firmware.h b/include/linux/firmware.h
index e154c1005cd1..59529330efd6 100644
--- a/include/linux/firmware.h
+++ b/include/linux/firmware.h
@@ -68,4 +68,11 @@ static inline void release_firmware(const struct firmware *fw)
 
 #endif
 
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+int request_firmware_direct(const struct firmware **fw, const char *name,
+                            struct device *device);
+#else
+#define request_firmware_direct request_firmware
+#endif
+
 #endif