Re: [PATCH 8/9] rfkill: Userspace control for airplane mode

Provide an interface for the airplane-mode indicator be controlled from
userspace. User has to first acquire the control through
RFKILL_OP_AIRPLANE_MODE_ACQUIRE and keep the fd open for the whole time
it wants to be in control of the indicator. Closing the fd or using
RFKILL_OP_AIRPLANE_MODE_RELEASE restores the default policy.

To change state of the indicator, the RFKILL_OP_AIRPLANE_MODE_CHANGE
operation is used, passing the value on "struct rfkill_event.soft". If
the caller has not acquired the airplane-mode control beforehand, the
operation fails.

Signed-off-by: João Paulo Rechi Vita <redacted>
---
 Documentation/rfkill.txt    | 10 ++++++++++
 include/uapi/linux/rfkill.h |  3 +++
 net/rfkill/core.c           | 47 ++++++++++++++++++++++++++++++++++++++++++---
 3 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/net/rfkill/core.c b/net/rfkill/core.c
index fb11547..8067701 100644
--- a/net/rfkill/core.c
+++ b/net/rfkill/core.c

@@ -1207,6 +1210,34 @@ static ssize_t rfkill_fop_write(struct file *file, const char __user *buf,

        mutex_lock(&rfkill_global_mutex);

+       if (ev.op == RFKILL_OP_AIRPLANE_MODE_ACQUIRE) {
+               if (rfkill_apm_owned && !data->is_apm_owner) {
+                       count = -EACCES;
+               } else {
+                       rfkill_apm_owned = true;
+                       data->is_apm_owner = true;
+               }
+       }
+
+       if (ev.op == RFKILL_OP_AIRPLANE_MODE_RELEASE) {
+               if (rfkill_apm_owned && !data->is_apm_owner) {

+                       count = -EACCES;
+               } else {
+                       bool state = rfkill_global_states[RFKILL_TYPE_ALL].cur;
+
+                       rfkill_apm_owned = false;
+                       data->is_apm_owner = false;
+                       rfkill_apm_led_trigger_event(state);
+               }
+       }
+
+       if (ev.op == RFKILL_OP_AIRPLANE_MODE_CHANGE) {
+               if (rfkill_apm_owned && data->is_apm_owner)
+                       rfkill_apm_led_trigger_event(ev.soft);
+               else
+                       count = -EACCES;
+       }
+
        if (ev.op == RFKILL_OP_CHANGE_ALL)
                rfkill_update_global_state(ev.type, ev.soft);

@@ -1230,7 +1261,17 @@ static int rfkill_fop_release(struct inode *inode, struct file *file)
        struct rfkill_int_event *ev, *tmp;

        mutex_lock(&rfkill_global_mutex);
+
+       if (data->is_apm_owner) {
+               bool state = rfkill_global_states[RFKILL_TYPE_ALL].cur;
+
+               rfkill_apm_owned = false;
+               data->is_apm_owner = false;
+               rfkill_apm_led_trigger_event(state);