firmware_class: Rework usermodehelper check

Instead of two functions, read_lock_usermodehelper() and
usermodehelper_is_disabled(), used in combination, introduce
usermodehelper_read_trylock() that will only return with umhelper_sem
held if usermodehelper_disabled is unset (and will return -EAGAIN
otherwise) and make _request_firmware() use it.

Rename read_unlock_usermodehelper() to
usermodehelper_read_unlock() to follow the naming convention of the
new function.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable@vger.kernel.org

1 files changed, 5 insertions, 6 deletions

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 6c9387d646ec..deee871e509c 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -533,12 +533,10 @@ static int _request_firmware(const struct firmware **firmware_p,
                 return 0;
         }
 
-        read_lock_usermodehelper();
-
-        if (WARN_ON(usermodehelper_is_disabled())) {
+        retval = usermodehelper_read_trylock();
+        if (WARN_ON(retval)) {
                 dev_err(device, "firmware: %s will not be loaded\n", name);
-                retval = -EBUSY;
-                goto out;
+                goto out_nolock;
         }
 
         if (uevent)
@@ -573,8 +571,9 @@ static int _request_firmware(const struct firmware **firmware_p,
         fw_destroy_instance(fw_priv);
 
 out:
-        read_unlock_usermodehelper();
+        usermodehelper_read_unlock();
 
+out_nolock:
         if (retval) {
                 release_firmware(firmware);
                 *firmware_p = NULL;