PM: Print a warning if firmware is requested when tasks are frozen

Some drivers erroneously use request_firmware() from their ->resume()
(or ->thaw(), or ->restore()) callbacks, which is not going to work
unless the firmware has been built in.  This causes system resume to
stall until the firmware-loading timeout expires, which makes users
think that the resume has failed and reboot their machines
unnecessarily.  For this reason, make _request_firmware() print a
warning and return immediately with error code if it has been called
when tasks are frozen and it's impossible to start any new usermode
helpers.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Reviewed-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 8c798ef7f13f..bbb03e6f7255 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -521,6 +521,11 @@ static int _request_firmware(const struct firmware **firmware_p,
         if (!firmware_p)
                 return -EINVAL;
 
+        if (WARN_ON(usermodehelper_is_disabled())) {
+                dev_err(device, "firmware: %s will not be loaded\n", name);
+                return -EBUSY;
+        }
+
         *firmware_p = firmware = kzalloc(sizeof(*firmware), GFP_KERNEL);
         if (!firmware) {
                 dev_err(device, "%s: kmalloc(struct firmware) failed\n",