restore: unify handling of thread args of leaders and other threads

Currently we have an array for thread_args, but leader's thread_args
is a part of task_args.
Here is two problems. The array has a space for leader's thread args,
but it is unused. Code which fills thread args is duplicated two
times. This patch fixed both problem. It replaces thread_args on a
pointer from task_args and deletes code, which fills leaders
thread_args.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-restore.c

@@ -1807,12 +1807,6 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 	task_args	= mem;
 	thread_args	= mem + restore_task_vma_len;
 
-	/*
-	 * Adjust stack.
-	 */
-	new_sp = RESTORE_ALIGN_STACK((long)task_args->t.mem_zone.stack,
-			sizeof(task_args->t.mem_zone.stack));
-
 	/*
 	 * Get a reference to shared memory area which is
 	 * used to signal if shmem restoration complete
@@ -1861,7 +1855,6 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 
 	BUG_ON(core->mtype != CORE_ENTRY__MARCH__X86_64);
 
-	task_args->t.pid	= pid;
 	task_args->logfd	= log_get_fd();
 	task_args->loglevel	= log_get_loglevel();
 	task_args->sigchld_act	= sigchld_act;
@@ -1874,12 +1867,14 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 	for (i = 0; i < current->nr_threads; i++) {
 		int fd_core;
 		CoreEntry *tcore;
+
 		thread_args[i].pid = current->threads[i].virt;
 
 		/* skip self */
-		if (thread_args[i].pid == pid)
-			continue;
-
+		if (thread_args[i].pid == pid) {
+			task_args->t = thread_args + i;
+			tcore = core;
+		} else {
 			fd_core = open_image_ro(CR_FD_CORE, thread_args[i].pid);
 			if (fd_core < 0) {
 				pr_err("Can't open core data for thread %d\n",
@@ -1889,8 +1884,9 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 
 			ret = pb_read_one(fd_core, &tcore, PB_CORE);
 			close(fd_core);
+		}
 
-		if (tcore->tc || tcore->ids) {
+		if ((tcore->tc || tcore->ids) && thread_args[i].pid != pid) {
 			pr_err("Thread has optional fields present %d\n",
 			       thread_args[i].pid);
 			ret = -1;
@@ -1921,6 +1917,7 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 		if (sigreturn_prep_xsave_frame(&thread_args[i], core))
 			goto err;
 
+		if (thread_args[i].pid != pid)
 			core_entry__free_unpacked(tcore, NULL);
 
 		pr_info("Thread %4d stack %8p heap %8p rt_sigframe %8p\n",
@@ -1930,24 +1927,16 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 
 	}
 
-	task_args->t.clear_tid_addr	= core->thread_info->clear_tid_addr;
-	task_args->ids			= *core->ids;
-	task_args->t.gpregs		= *core->thread_info->gpregs;
-	task_args->t.blk_sigset		= core->tc->blk_sigset;
-	task_args->t.has_blk_sigset	= true;
+	task_args->t->blk_sigset	= core->tc->blk_sigset;
+	task_args->t->has_blk_sigset	= true;
 
-	if (core->thread_core) {
-		task_args->t.has_futex		= true;
-		task_args->t.futex_rla		= core->thread_core->futex_rla;
-		task_args->t.futex_rla_len	= core->thread_core->futex_rla_len;
-
-		ret = prep_sched_info(&task_args->t.sp, core->thread_core);
-		if (ret)
-			goto err;
-	}
+	/*
+	 * Adjust stack.
+	 */
+	new_sp = RESTORE_ALIGN_STACK((long)task_args->t->mem_zone.stack,
+			sizeof(task_args->t->mem_zone.stack));
 
-	if (sigreturn_prep_xsave_frame(&task_args->t, core))
-		goto err;
+	task_args->ids			= *core->ids;
 
 	/* No longer need it */
 	core_entry__free_unpacked(core, NULL);
@@ -1980,7 +1969,7 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 		"task_args->nr_threads: %d\n"
 		"task_args->clone_restore_fn: %p\n"
 		"task_args->thread_args: %p\n",
-		task_args, task_args->t.pid,
+		task_args, task_args->t->pid,
 		task_args->nr_threads,
 		task_args->clone_restore_fn,
 		task_args->thread_args);

include/restorer.h

@@ -93,7 +93,7 @@ struct thread_restore_args {
 } __aligned(sizeof(long));
 
 struct task_restore_core_args {
-	struct thread_restore_args	t;			/* thread group leader */
+	struct thread_restore_args	*t;			/* thread group leader */
 
 	int				fd_exe_link;		/* opened self->exe file */
 	int				logfd;

pie/restorer.c

@@ -627,9 +627,9 @@ long __export_restore_task(struct task_restore_core_args *args)
 	 * registers from the frame, set them up and
 	 * finally pass execution to the new IP.
 	 */
-	rt_sigframe = (void *)args->t.mem_zone.rt_sigframe + 8;
+	rt_sigframe = (void *)args->t->mem_zone.rt_sigframe + 8;
 
-	if (restore_thread_common(rt_sigframe, &args->t))
+	if (restore_thread_common(rt_sigframe, args->t))
 		goto core_restore_end;
 
 	/*
@@ -674,7 +674,7 @@ long __export_restore_task(struct task_restore_core_args *args)
 			char last_pid_buf[16], *s;
 
 			/* skip self */
-			if (thread_args[i].pid == args->t.pid)
+			if (thread_args[i].pid == args->t->pid)
 				continue;
 
 			mutex_lock(&args->rst_lock);