dde_linux: fix timer callback compatibility with older drivers

Fixes #3137

repos/dde_linux/src/drivers/nic/fec/lx_emul.cc

@@ -728,9 +728,16 @@ void reinit_completion(struct completion *work)
 }
 
 
+/*
+ * For compatibility with 4.4.3 drivers, the argument of this callback function
+ * is the 'data' member of the 'timer_list' object, which normally points to
+ * the 'timer_list' object itself when initialized with 'timer_setup()', but
+ * here it was overridden  in '__wait_completion()' to point to the 'Lx::Task'
+ * object instead.
+ */
 static void _completion_timeout(struct timer_list *t)
 {
-	Lx::Task *task = (Lx::Task *)t->data;
+	Lx::Task *task = (Lx::Task *)t;
 	task->unblock();
 }
 

repos/dde_linux/src/include/lx_emul/impl/timer.h

@@ -30,6 +30,15 @@ void timer_setup(struct timer_list *timer,
 {
 	timer->function = function;
 	timer->flags    = flags;
+
+	/*
+	 * For compatibility with 4.4.3 drivers, the 'data' member is passed as
+	 * argument to the callback function. Since the 4.16.3 callback function
+	 * interface has a 'timer_list' pointer as argument, the 'data' member
+	 * points to the 'timer_list' object  itself when set up with this
+	 * function.
+	 */
+	timer->data     = (unsigned long)timer;
 }
 
 

repos/dde_linux/src/include/lx_emul/timer.h

@@ -29,7 +29,14 @@ struct timer_list
 	void          (*function)(struct timer_list*);
 	unsigned int  flags;
 
-	unsigned long data; /* keep for compat with 4.4.3 drivers */
+	/*
+	 * For compatibility with 4.4.3 drivers, the 'data' member is kept and
+	 * passed as argument to the callback function. Since the 4.16.3 callback
+	 * function interface has a 'timer_list' pointer as argument, the 'data'
+	 * member points to the 'timer_list' object itself when set up with the
+	 * 'timer_setup()' function.
+	 */
+	unsigned long data;
 };
 
 int  mod_timer(struct timer_list *timer, unsigned long expires);

repos/dde_linux/src/lib/usb/lx_emul.cc

@@ -987,9 +987,9 @@ signed long schedule_timeout_uninterruptible(signed long timeout)
 #include <lx_emul/impl/completion.h>
 
 
-static void _completion_timeout(struct timer_list *t)
+static void _completion_timeout(unsigned long t)
 {
-	Lx::Task *task = (Lx::Task *)t->data;
+	Lx::Task *task = (Lx::Task *)t;
 	task->unblock();
 }
 
@@ -1000,8 +1000,8 @@ long __wait_completion(struct completion *work, unsigned long timeout)
 	unsigned long j = timeout ? jiffies + timeout : 0;
 
 	if (timeout) {
-		timer_setup(&t, _completion_timeout, 0u);
-		t.data = (unsigned long)Lx::scheduler().current();
+		setup_timer(&t, _completion_timeout,
+		            (unsigned long)Lx::scheduler().current());
 		mod_timer(&t, j);
 	}
 
@@ -1132,9 +1132,16 @@ struct callback_timer {
 	unsigned long data;
 };
 
+/*
+ * For compatibility with 4.4.3 drivers, the argument of this callback function
+ * is the 'data' member of the 'timer_list' object, which normally points to
+ * the 'timer_list' object itself when initialized with 'timer_setup()', but
+ * here it was overridden in 'setup_timer()' to point to the 'callback_timer'
+ * object instead.
+ */
 static void timer_callback(struct timer_list *t)
 {
-	struct callback_timer * tc = (struct callback_timer *)t->data;
+	struct callback_timer * tc = (struct callback_timer *)t;
 	tc->function(tc->data);
 }
 

repos/dde_linux/src/lx_kit/timer.cc

@@ -60,8 +60,14 @@ class Lx_kit::Timer : public Lx::Timer
 				case LIST:
 					{
 						timer_list *t = static_cast<timer_list *>(timer);
-						if (t->function)
-							t->function(t);
+						if (t->function) {
+							/*
+							 * Pass 't->data' instead of 't' for compatibility
+							 * with 4.4.3 drivers. When set up with
+							 * 'timer_setup()', 't->data' matches 't'.
+							 */
+							t->function((struct timer_list*)t->data);
+						}
 					}
 					break;