criu: dump: prepare parasite control for threads at infect time

Currently parasite_thread_ctl for non-leader threads is initialized after we
stop the compel daemon. Moving this initialization earlier will allow us to
make stack pointers of all threads available during memory dump.
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>

criu/cr-dump.c

@@ -841,6 +841,7 @@ static int collect_file_locks(void)
 static int dump_task_thread(struct parasite_ctl *parasite_ctl,
 				const struct pstree_item *item, int id)
 {
+	struct parasite_thread_ctl *tctl = dmpi(item)->thread_ctls[id];
 	struct pid *tid = &item->threads[id];
 	CoreEntry *core = item->core[id];
 	pid_t pid = tid->real;
@@ -851,7 +852,7 @@ static int dump_task_thread(struct parasite_ctl *parasite_ctl,
 	pr_info("Dumping core for thread (pid: %d)\n", pid);
 	pr_info("----------------------------------------\n");
 
-	ret = parasite_dump_thread_seized(parasite_ctl, id, tid, core);
+	ret = parasite_dump_thread_seized(tctl, parasite_ctl, id, tid, core);
 	if (ret) {
 		pr_err("Can't dump thread for pid %d\n", pid);
 		goto err;

criu/include/parasite-syscall.h

@@ -21,6 +21,7 @@ struct parasite_dump_cgroup_args;
 struct rt_sigframe;
 
 struct parasite_ctl;
+struct parasite_thread_ctl;
 
 extern int parasite_dump_sigacts_seized(struct parasite_ctl *ctl, struct pstree_item *);
 extern int parasite_dump_itimers_seized(struct parasite_ctl *ctl, struct pstree_item *);
@@ -32,8 +33,9 @@ extern int parasite_dump_posix_timers_seized(struct proc_posix_timers_stat *proc
 extern int parasite_dump_misc_seized(struct parasite_ctl *ctl, struct parasite_dump_misc *misc);
 extern int parasite_dump_creds(struct parasite_ctl *ctl, struct _CredsEntry *ce);
 extern int parasite_dump_thread_leader_seized(struct parasite_ctl *ctl, int pid, struct _CoreEntry *core);
-extern int parasite_dump_thread_seized(struct parasite_ctl *ctl, int id,
-					struct pid *tid, struct _CoreEntry *core);
+extern int parasite_dump_thread_seized(struct parasite_thread_ctl *tctl,
+				       struct parasite_ctl *ctl, int id,
+				       struct pid *tid, struct _CoreEntry *core);
 extern int dump_thread_core(int pid, CoreEntry *core,
 					const struct parasite_dump_thread *dt);
 

criu/include/pstree.h

@@ -56,6 +56,7 @@ struct dmp_info {
 	struct ns_id *netns;
 	struct page_pipe *mem_pp;
 	struct parasite_ctl *parasite_ctl;
+	struct parasite_thread_ctl **thread_ctls;
 };
 
 static inline struct dmp_info *dmpi(const struct pstree_item *i)

criu/parasite-syscall.c

@@ -162,7 +162,8 @@ int parasite_dump_thread_leader_seized(struct parasite_ctl *ctl, int pid, CoreEn
 	return dump_thread_core(pid, core, args);
 }
 
-int parasite_dump_thread_seized(struct parasite_ctl *ctl, int id,
+int parasite_dump_thread_seized(struct parasite_thread_ctl *tctl,
+				struct parasite_ctl *ctl, int id,
 				struct pid *tid, CoreEntry *core)
 {
 	struct parasite_dump_thread *args;
@@ -171,7 +172,6 @@ int parasite_dump_thread_seized(struct parasite_ctl *ctl, int id,
 	CredsEntry *creds = tc->creds;
 	struct parasite_dump_creds *pc;
 	int ret;
-	struct parasite_thread_ctl *tctl;
 
 	BUG_ON(id == 0); /* Leader is dumped in dump_task_core_all */
 
@@ -180,10 +180,6 @@ int parasite_dump_thread_seized(struct parasite_ctl *ctl, int id,
 	pc = args->creds;
 	pc->cap_last_cap = kdat.last_cap;
 
-	tctl = compel_prepare_thread(ctl, pid);
-	if (!tctl)
-		return -1;
-
 	tc->has_blk_sigset = true;
 	memcpy(&tc->blk_sigset, compel_thread_sigmask(tctl), sizeof(k_rtsigset_t));
 	ret = compel_get_thread_regs(tctl, save_task_regs, core);
@@ -468,12 +464,39 @@ static int make_sigframe(void *arg, struct rt_sigframe *sf, struct rt_sigframe *
 	return construct_sigframe(sf, rtsf, bs, (CoreEntry *)arg);
 }
 
+static int parasite_prepare_threads(struct parasite_ctl *ctl,
+				    struct pstree_item *item)
+{
+	struct parasite_thread_ctl **thread_ctls;
+	int i;
+
+	thread_ctls = xzalloc(sizeof(*thread_ctls) * item->nr_threads);
+	if (!thread_ctls)
+		return -1;
+
+	for (i = 0; i < item->nr_threads; i++) {
+		struct pid *tid = &item->threads[i];
+
+		if (item->pid->real == tid->real)
+			continue;
+
+		thread_ctls[i] = compel_prepare_thread(ctl, tid->real);
+		if (!thread_ctls[i])
+			return -1;
+	}
+
+	dmpi(item)->thread_ctls = thread_ctls;
+
+	return 0;
+}
+
 struct parasite_ctl *parasite_infect_seized(pid_t pid, struct pstree_item *item,
 		struct vm_area_list *vma_area_list)
 {
 	struct parasite_ctl *ctl;
 	struct infect_ctx *ictx;
 	unsigned long p;
+	int ret;
 
 	BUG_ON(item->threads[0].real != pid);
 
@@ -487,6 +510,10 @@ struct parasite_ctl *parasite_infect_seized(pid_t pid, struct pstree_item *item,
 	if (!ctl)
 		return NULL;
 
+	ret = parasite_prepare_threads(ctl, item);
+	if (ret)
+		return NULL;
+
 	ictx = compel_infect_ctx(ctl);
 
 	ictx->open_proc = do_open_proc;
@@ -532,4 +559,3 @@ struct parasite_ctl *parasite_infect_seized(pid_t pid, struct pstree_item *item,
 
 	return ctl;
 }
-