Fix data race when accessing dongle children

src/daemon/device.c

@@ -17,6 +17,7 @@ pthread_cond_t macrovar[DEV_MAX] = { [0 ... DEV_MAX-1] = PTHREAD_COND_INITIALIZE
 pthread_cond_t macroint[DEV_MAX];                                                           ///< Should a macro thread's sleep be interrupted, due to repeated key press?
 pthread_mutex_t interruptmutex[DEV_MAX] = { [0 ... DEV_MAX-1] = PTHREAD_MUTEX_INITIALIZER };///< Used for interrupt transfers
 pthread_cond_t interruptcond[DEV_MAX];                                                      ///< Same as above
+pthread_mutex_t childrenmutex[DEV_MAX] = { [0 ... DEV_MAX-1] = PTHREAD_MUTEX_INITIALIZER };
 
 ///
 /// \brief cond_nanosleep matches semantics of pthread_cond_timedwait, but with a relative wake time
@@ -175,7 +176,7 @@ int _start_dev(usbdevice* kb, int makeactive){
     ///
     if(IS_SINGLE_EP(kb))
         kb->features &= ~FEAT_BIND;
-    
+
     ///
     /// The Polaris doesn't support hardware profiles, so remove the FEAT_HWLOAD bit.
     ///
@@ -187,7 +188,7 @@ int _start_dev(usbdevice* kb, int makeactive){
     ///
     if(USES_FILE_HWSAVE(kb))
         kb->features &= ~FEAT_HWLOAD;
-    
+
     ///
     /// K66 has no backlight
     ///

src/daemon/device.h

@@ -60,6 +60,10 @@ extern pthread_mutex_t interruptmutex[DEV_MAX];
 extern pthread_cond_t interruptcond[DEV_MAX];
 #define intcond(kb) (interruptcond + INDEX_OF(kb, keyboard))
 
+// Mutex to access the children for each device
+extern pthread_mutex_t childrenmutex[DEV_MAX];
+#define cmutex(kb) (childrenmutex + INDEX_OF(kb, keyboard))
+
 int init_cond_monotonic(void);
 
 // Sets up device hardware, after software initialization is finished. Also used during resets

src/daemon/device_bragi.c

@@ -205,7 +205,9 @@ static inline int bragi_dongle_probe(usbdevice* kb){
             subkb->bragi_child_id = i;
 
             // Add the device to our children array
+            pthread_mutex_lock(cmutex(kb));
             kb->children[i-1] = subkb;
+            pthread_mutex_unlock(cmutex(kb));
 
             // Fill dev information
             ushort vid = bragi_get_property(subkb, BRAGI_VID);

src/daemon/keymap.c

@@ -590,6 +590,7 @@ void process_input_urb(void* context, unsigned char* buffer, int urblen, ushort
     // All device specific events have the max length of bytes
     usbdevice* targetkb = kb;
     if(kb->protocol == PROTO_BRAGI && IS_DONGLE(kb)){
+        pthread_mutex_lock(cmutex(kb));
         if(urblen == kb->out_ep_packet_size){
             // Extract the device id
             int devid = firstbyte & 0x7;
@@ -608,6 +609,7 @@ void process_input_urb(void* context, unsigned char* buffer, int urblen, ushort
                 ckb_err("kb->children[0] is NULL");
 #endif
         }
+        pthread_mutex_unlock(cmutex(kb));
     }
 
     // If the response starts with CMD_GET (0x0e) for NXP, or it came from a bragi command EP, that means it needs to go to os_usbrecv()