firmware: enable to force disable the fallback mechanism at run time

You currently need four different kernel builds to test the firmware
API fully. By adding a proc knob to force disable the fallback mechanism
completely we are able to reduce the amount of kernels you need built
to test the firmware API down to two.

Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/base/firmware_loader/fallback_table.c b/drivers/base/firmware_loader/fallback_table.c
index 92365e053e30..7428659d8df9 100644
--- a/drivers/base/firmware_loader/fallback_table.c
+++ b/drivers/base/firmware_loader/fallback_table.c
@@ -39,6 +39,15 @@ struct ctl_table firmware_config_table[] = {
                 .extra1         = &zero,
                 .extra2         = &one,
         },
+        {
+                .procname       = "ignore_sysfs_fallback",
+                .data           = &fw_fallback_config.ignore_sysfs_fallback,
+                .maxlen         = sizeof(unsigned int),
+                .mode           = 0644,
+                .proc_handler   = proc_douintvec_minmax,
+                .extra1         = &zero,
+                .extra2         = &one,
+        },
         { }
 };
 EXPORT_SYMBOL_GPL(firmware_config_table);