[CRIU] [crtools-bot] restore: clean up code, which synchronizes resume of tasks (v2)

[Cyrill Gorcunov]

The commit is pushed to "master" and will appear on git://github.com/cyrillos/crtools.git
------>
commit 27b20dfcc6ad48512637b62624e2712514cd9723
Author: Andrey Vagin <avagin at openvz.org>
Date:   Thu Feb 2 13:32:55 2012 +0300

    restore: clean up code, which synchronizes resume of tasks (v2)
    
    I added two mechanism of synchronization. The second one is better.
    This patch deletes the first one.
    
    Before we had an entry (pid and lock) for each tasks and all this
    entries were shared between all processes. Now we don't need "lock"
    and we use pids from crtools to kill all processes if someone failed.
    
    v2: s/malloc/xmalloc
    
    Signed-off-by: Andrey Vagin <avagin at openvz.org>
    Acked-by: Pavel Emelyanov <xemul at parallels.com>
    Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
 cr-restore.c       |   44 +++++++++++++++++++-------------------------
 include/restorer.h |   18 ------------------
 restorer.c         |    3 ---
 3 files changed, 19 insertions(+), 46 deletions(-)

diff --git a/cr-restore.c b/cr-restore.c
index 0aeedfd..7a1021c 100644
--- a/cr-restore.c
+++ b/cr-restore.c
@@ -79,18 +79,16 @@ struct pipe_list_entry {
 
 static struct task_entries *task_entries;
 
-static void task_add_entry(int pid)
-{
-	int *nr = &task_entries->nr;
-	struct task_entry *e = &task_entries->entries[*nr];
-
-	(*nr)++;
-
-	BUG_ON((*nr) * sizeof(struct task_entry) +
-		sizeof(struct task_entries) > TASK_ENTRIES_SIZE);
+static struct task_pids {
+	int nr;
+	int arr[];
+} *task_pids;
 
-	e->pid = pid;
-	e->done = 0;
+static void task_add_pid(int pid)
+{
+	BUG_ON(sizeof(struct task_pids) + task_pids->nr * sizeof(int) > PAGE_SIZE);
+	task_pids->arr[task_pids->nr] = pid;
+	task_pids->nr++;
 }
 
 static struct shmem_id *shmem_ids;
@@ -372,6 +370,11 @@ static int prepare_shared(int ps_fd)
 
 	pr_info("Preparing info about shared resources\n");
 
+	task_pids = xmalloc(PAGE_SIZE);
+	if (task_pids == NULL)
+		return -1;
+	task_pids->nr = 0;
+
 	shmems = mmap(NULL, SHMEMS_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, 0, 0);
 	if (shmems == MAP_FAILED) {
 		pr_perror("Can't map shmem");
@@ -417,7 +420,9 @@ static int prepare_shared(int ps_fd)
 		if (ret < 0)
 			break;
 
-		task_add_entry(e.pid);
+		task_add_pid(e.pid);
+
+		task_entries->nr++;
 
 		lseek(ps_fd, e.nr_children * sizeof(u32) + e.nr_threads * sizeof(u32), SEEK_CUR);
 	}
@@ -1128,12 +1133,7 @@ static int restore_one_zobie(int pid, int exit_code)
 	pr_info("Restoring zombie with %d code\n", exit_code);
 
 	if (task_entries != NULL) {
-		struct task_entry *task_entry;
-
-		task_entry = task_get_entry(task_entries, pid);
-
 		cr_wait_dec(&task_entries->nr_in_progress);
-		cr_wait_set(&task_entry->done, 1);
 		cr_wait_while(&task_entries->start, CR_STATE_RESTORE);
 
 		zombie_prepare_signals();
@@ -1410,17 +1410,11 @@ static int restore_root_task(int fd, struct cr_options *opts)
 	ret = cr_wait_until_greater(&task_entries->nr_in_progress, 0);
 	if (ret < 0) {
 		pr_err("Someone can't be restored\n");
-		for (i = 0; i < task_entries->nr; i++)
-			kill(task_entries->entries[i].pid, SIGKILL);
+		for (i = 0; i < task_pids->nr; i++)
+			kill(task_pids->arr[i], SIGKILL);
 		return 1;
 	}
 
-	for (i = 0; i < task_entries->nr; i++) {
-		pr_info("Wait while the task %d restored\n",
-				task_entries->entries[i].pid);
-		cr_wait_while(&task_entries->entries[i].done, 0);
-	}
-
 	cr_wait_set(&task_entries->nr_in_progress, task_entries->nr);
 	cr_wait_set(&task_entries->start, CR_STATE_RESTORE_SIGCHLD);
 	cr_wait_until(&task_entries->nr_in_progress, 0);
diff --git a/include/restorer.h b/include/restorer.h
index 7e4fa55..5152a86 100644
--- a/include/restorer.h
+++ b/include/restorer.h
@@ -202,16 +202,10 @@ enum {
 	CR_STATE_COMPLETE
 };
 
-struct task_entry {
-	int pid;
-	u32 done; // futex
-};
-
 struct task_entries {
 	int nr;
 	u32 nr_in_progress;
 	u32 start; //futex
-	struct task_entry entries[0];
 };
 
 
@@ -232,16 +226,4 @@ find_shmem_by_pid(struct shmems *shmems, unsigned long start, int pid)
 	return NULL;
 }
 
-static always_inline struct task_entry *
-task_get_entry(struct task_entries *base, int pid)
-{
-	int i;
-
-	for (i = 0; i < base->nr; i++)
-		if (base->entries[i].pid == pid)
-			return &base->entries[i];
-
-	return NULL;
-}
-
 #endif /* CR_RESTORER_H__ */
diff --git a/restorer.c b/restorer.c
index 5755a05..5791dc9 100644
--- a/restorer.c
+++ b/restorer.c
@@ -624,10 +624,7 @@ long restore_task(struct task_restore_core_args *args)
 
 	restore_creds(&args->creds);
 
-	task_entry = task_get_entry(args->task_entries, my_pid);
-
 	cr_wait_dec(&args->task_entries->nr_in_progress);
-	cr_wait_set(&task_entry->done, 1);
 
 	write_num(sys_getpid());
 	write_string_n(": Restored");