crtools: Sanitize the tasklist states switch

Introduce a helper for walking the list and sending signals.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>

cr-dump.c

@@ -1166,6 +1166,31 @@ err:
 	return ret;
 }
 
+static void pstree_switch_state(struct list_head *list,
+		enum cr_task_state state, int leader_only)
+{
+	static const int state_sigs[] = {
+		[CR_TASK_STOP] = SIGSTOP,
+		[CR_TASK_RUN] = SIGCONT,
+		[CR_TASK_KILL] = SIGKILL,
+	};
+
+	struct pstree_item *item;
+
+	/*
+	 * Since ptrace-seize doesn't work on frozen tasks
+	 * we stick with explicit tasks stopping via stop
+	 * signal, but in future it's aimed to switch to
+	 * kernel freezer.
+	 */
+
+	list_for_each_entry(item, list, list) {
+		kill(item->pid, state_sigs[state]);
+		if (leader_only)
+			break;
+	}
+}
+
 int cr_dump_tasks(pid_t pid, struct cr_options *opts)
 {
 	LIST_HEAD(pstree_list);
@@ -1187,17 +1212,7 @@ int cr_dump_tasks(pid_t pid, struct cr_options *opts)
 	if (collect_sockets())
 		goto err;
 
-	/*
-	 * Since ptrace-seize doesn't work on frozen tasks
-	 * we stick with explicit tasks stopping via stop
-	 * signal, but in future it's aimed to switch to
-	 * kernel freezer.
-	 */
-	list_for_each_entry(item, &pstree_list, list) {
-		stop_task(item->pid);
-		if (opts->leader_only)
-			break;
-	}
+	pstree_switch_state(&pstree_list, CR_TASK_STOP, opts->leader_only);
 
 	list_for_each_entry(item, &pstree_list, list) {
 
@@ -1254,22 +1269,11 @@ int cr_dump_tasks(pid_t pid, struct cr_options *opts)
 
 err:
 	switch (opts->final_state) {
-	case CR_TASK_LEAVE_RUNNING:
-		list_for_each_entry(item, &pstree_list, list) {
-			continue_task(item->pid);
-			if (opts->leader_only)
-				break;
-		}
-		break;
+	case CR_TASK_RUN:
 	case CR_TASK_KILL:
-		list_for_each_entry(item, &pstree_list, list) {
-			kill_task(item->pid);
-			if (opts->leader_only)
-				break;
-		}
-		break;
-	case CR_TASK_LEAVE_STOPPED:
-	default:
+		pstree_switch_state(&pstree_list,
+				opts->final_state, opts->leader_only);
+	case CR_TASK_STOP: /* they are already stopped */
 		break;
 	}
 

crtools.c

@@ -296,7 +296,7 @@ int main(int argc, char *argv[])
 			break;
 		case 'c':
 			opts.show_pages_content	= true;
-			opts.final_state = CR_TASK_LEAVE_RUNNING;
+			opts.final_state = CR_TASK_RUN;
 			break;
 		case 'f':
 			opts.show_dump_file = optarg;

include/crtools.h

@@ -28,15 +28,15 @@ enum {
 	CR_FD_MAX
 };
 
-enum cr_task_final_state {
-	CR_TASK_LEAVE_STOPPED,		/* leave tasks stopped after dump/restore */
-	CR_TASK_LEAVE_RUNNING,		/* leave tasks running after dump/restore */
-	CR_TASK_KILL,			/* kill tasks after dump */
+enum cr_task_state {
+	CR_TASK_RUN,
+	CR_TASK_STOP,
+	CR_TASK_KILL,
 };
 
 struct cr_options {
 	bool				leader_only;
-	enum cr_task_final_state	final_state;
+	enum cr_task_state		final_state;
 	bool				show_pages_content;
 	char				*show_dump_file;
 };

include/util.h

@@ -98,10 +98,6 @@ extern void printk(const char *format, ...);
 
 #define BUG_ON(condition)	BUG_ON_HANDLER((condition))
 
-#define stop_task(pid)		kill(pid, SIGSTOP)
-#define kill_task(pid)		kill(pid, SIGKILL)
-#define continue_task(pid)	kill(pid, SIGCONT)
-
 #define write_ptr(fd, ptr)			\
 	write(fd, (ptr), sizeof(*(ptr)))
 

ptrace.c

@@ -61,7 +61,7 @@ err:
 	return ret;
 
 err_cont:
-	continue_task(pid);
+	kill(pid, SIGCONT);
 	goto err;
 }