[CRIU] [PATCH 3/4] restore: unify handling of thread args of leaders and other threads

[Andrey Vagin]

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 at openvz.org>
---
 cr-restore.c       | 58 +++++++++++++++++++++++-------------------------------
 include/restorer.h |  2 +-
 pie/restorer.c     |  6 +++---
 3 files changed, 29 insertions(+), 37 deletions(-)

diff --git a/cr-restore.c b/cr-restore.c
index 79f2a5a..8fe6288 100644
--- a/cr-restore.c
+++ b/cr-restore.c
@@ -1676,12 +1676,6 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 	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
 	 * from low-level restore code.
@@ -1729,7 +1723,6 @@ 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;
@@ -1742,23 +1735,26 @@ 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",
+				       thread_args[i].pid);
+				goto err;
+			}
 
-		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",
-			       thread_args[i].pid);
-			goto err;
+			ret = pb_read_one(fd_core, &tcore, PB_CORE);
+			close(fd_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;
@@ -1786,7 +1782,8 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
 				goto err;
 		}
 
-		core_entry__free_unpacked(tcore, NULL);
+		if (thread_args[i].pid != pid)
+			core_entry__free_unpacked(tcore, NULL);
 
 		pr_info("Thread %4d stack %8p heap %8p rt_sigframe %8p\n",
 				i, thread_args[i].mem_zone.stack,
@@ -1795,21 +1792,16 @@ 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;
+	/*
+	 * Adjust stack.
+	 */
+	new_sp = RESTORE_ALIGN_STACK((long)task_args->t->mem_zone.stack,
+			sizeof(task_args->t->mem_zone.stack));
 
-		ret = prep_sched_info(&task_args->t.sp, core->thread_core);
-		if (ret)
-			goto err;
-	}
+	task_args->ids			= *core->ids;
 
 	/* No longer need it */
 	core_entry__free_unpacked(core, NULL);
@@ -1842,7 +1834,7 @@ 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);
diff --git a/include/restorer.h b/include/restorer.h
index 9011830..2d33635 100644
--- a/include/restorer.h
+++ b/include/restorer.h
@@ -82,7 +82,7 @@ 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;
diff --git a/pie/restorer.c b/pie/restorer.c
index b6211f1..e026d41 100644
--- a/pie/restorer.c
+++ b/pie/restorer.c
@@ -609,9 +609,9 @@ 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;
 
 	/*
@@ -656,7 +656,7 @@ 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);
-- 
1.7.11.7