criu: dump and restore a thread name

Reported-by: 志平 林 <larry.lin@outlook.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/cr-dump.c

@@ -716,6 +716,9 @@ int dump_thread_core(int pid, CoreEntry *core, const struct parasite_dump_thread
 			tc->has_pdeath_sig = true;
 			tc->pdeath_sig = ti->pdeath_sig;
 		}
+		tc->comm = xstrdup(ti->comm);
+		if (tc->comm == NULL)
+			return -1;
 	}
 	if (!ret)
 		ret = seccomp_dump_thread(pid, tc);

criu/cr-restore.c

@@ -3461,6 +3461,11 @@ static int sigreturn_restore(pid_t pid, struct task_restore_args *task_args, uns
 		if (construct_sigframe(sigframe, sigframe, blkset, tcore))
 			goto err;
 
+		if (thread_args[i].comm)
+			strncpy(thread_args[i].comm, tcore->thread_core->comm, TASK_COMM_LEN);
+		else
+			strncpy(thread_args[i].comm, core->tc->comm, TASK_COMM_LEN);
+
 		if (thread_args[i].pid != pid)
 			core_entry__free_unpacked(tcore, NULL);
 

criu/include/parasite.h

@@ -170,6 +170,7 @@ struct parasite_dump_thread {
 	tls_t				tls;
 	stack_t				sas;
 	int				pdeath_sig;
+	char				comm[TASK_COMM_LEN];
 	struct parasite_dump_creds	creds[0];
 };
 

criu/include/restorer.h

@@ -110,6 +110,8 @@ struct thread_restore_args {
 	void				*seccomp_filters_data;
 	unsigned int			seccomp_filters_n;
 	bool				seccomp_force_tsync;
+
+	char				comm[TASK_COMM_LEN];
 } __aligned(64);
 
 typedef long (*thread_restore_fcall_t) (struct thread_restore_args *args);

criu/pie/parasite.c

@@ -172,16 +172,28 @@ static int dump_thread_common(struct parasite_dump_thread *ti)
 
 	arch_get_tls(&ti->tls);
 	ret = sys_prctl(PR_GET_TID_ADDRESS, (unsigned long) &ti->tid_addr, 0, 0, 0);
-	if (ret)
+	if (ret) {
+		pr_err("Unable to get the clear_child_tid address: %d\n", ret);
 		goto out;
+	}
 
 	ret = sys_sigaltstack(NULL, &ti->sas);
-	if (ret)
+	if (ret) {
+		pr_err("Unable to get signal stack context: %d\n", ret);
 		goto out;
+	}
 
 	ret = sys_prctl(PR_GET_PDEATHSIG, (unsigned long)&ti->pdeath_sig, 0, 0, 0);
-	if (ret)
+	if (ret) {
+		pr_err("Unable to get the parent death signal: %d\n", ret);
+		goto out;
+	}
+
+	ret = sys_prctl(PR_GET_NAME, (unsigned long) &ti->comm, 0, 0, 0);
+	if (ret) {
+		pr_err("Unable to get the thread name: %d\n", ret);
 		goto out;
+	}
 
 	ret = dump_creds(ti->creds);
 out:

criu/pie/restorer.c

@@ -554,6 +554,12 @@ long __export_restore_thread(struct thread_restore_args *args)
 	if (restore_thread_common(args))
 		goto core_restore_end;
 
+	ret = sys_prctl(PR_SET_NAME, (unsigned long) &args->comm, 0, 0, 0);
+	if (ret) {
+		pr_err("Unable to set a thread name: %d\n", ret);
+		goto core_restore_end;
+	}
+
 	pr_info("%ld: Restored\n", sys_gettid());
 
 	restore_finish_stage(task_entries_local, CR_STATE_RESTORE);

images/core.proto

@@ -86,6 +86,8 @@ message thread_core_entry {
 
 	optional seccomp_mode		seccomp_mode	= 11;
 	optional uint32			seccomp_filter	= 12;
+
+	optional string			comm		= 13;
 }
 
 message task_rlimits_entry {