From 0d81417e390541fcc8aaf8be2e034afa7c7ce84f Mon Sep 17 00:00:00 2001
From: ZeyadYasser <zeyady98@gmail.com>
Date: Thu, 16 Apr 2020 15:58:18 +0200
Subject: [PATCH] criu: optimize find_unix_sk_by_ino()

Fixes: #339
Replaced the linear search with a hashtable lookup.

Signed-off-by: Zeyad Yasser <zeyady98@gmail.com>
---
 criu/files.c           |  1 +
 criu/include/sockets.h |  2 ++
 criu/sk-unix.c         | 19 ++++++++++++++++++-
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/criu/files.c b/criu/files.c
index a1fd26764..2cfc9040e 100644
--- a/criu/files.c
+++ b/criu/files.c
@@ -1749,5 +1749,6 @@ struct collect_image_info files_cinfo = {
 int prepare_files(void)
 {
 	init_fdesc_hash();
+	init_sk_info_hash();
 	return collect_image(&files_cinfo);
 }
diff --git a/criu/include/sockets.h b/criu/include/sockets.h
index cd98d18e0..e971f3efd 100644
--- a/criu/include/sockets.h
+++ b/criu/include/sockets.h
@@ -62,6 +62,8 @@ extern int unix_sk_id_add(unsigned int ino);
 extern int unix_sk_ids_parse(char *optarg);
 extern int unix_prepare_root_shared(void);
 
+extern void init_sk_info_hash(void);
+
 extern int do_dump_opt(int sk, int level, int name, void *val, int len);
 #define dump_opt(s, l, n, f)	do_dump_opt(s, l, n, f, sizeof(*f))
 extern int do_restore_opt(int sk, int level, int name, void *val, int len);
diff --git a/criu/sk-unix.c b/criu/sk-unix.c
index 048ff44ae..cbcf1f66c 100644
--- a/criu/sk-unix.c
+++ b/criu/sk-unix.c
@@ -903,6 +903,7 @@ struct unix_sk_info {
 	struct unix_sk_info	*peer;
 	struct pprep_head	peer_resolve; /* XXX : union with the above? */
 	struct file_desc	d;
+	struct hlist_node	hash; /* To lookup socket by ino */
 	struct list_head	connected; /* List of sockets, connected to me */
 	struct list_head	node; /* To link in peer's connected list  */
 	struct list_head	scm_fles;
@@ -934,11 +935,25 @@ struct scm_fle {
 #define USK_PAIR_SLAVE		0x2
 #define USK_GHOST_FDSTORE	0x4	/* bound but removed address */
 
+#define SK_INFO_HASH_SIZE	32
+
+static struct hlist_head sk_info_hash[SK_INFO_HASH_SIZE];
+
+void init_sk_info_hash(void)
+{
+	int i;
+
+	for (i = 0; i < SK_INFO_HASH_SIZE; i++)
+		INIT_HLIST_HEAD(&sk_info_hash[i]);
+}
+
 static struct unix_sk_info *find_unix_sk_by_ino(int ino)
 {
 	struct unix_sk_info *ui;
+	struct hlist_head *chain;
 
-	list_for_each_entry(ui, &unix_sockets, list) {
+	chain = &sk_info_hash[ino % SK_INFO_HASH_SIZE];
+	hlist_for_each_entry(ui, chain, hash) {
 		if (ui->ue->ino == ino)
 			return ui;
 	}
@@ -2044,6 +2059,7 @@ static int init_unix_sk_info(struct unix_sk_info *ui, UnixSkEntry *ue)
 	INIT_LIST_HEAD(&ui->node);
 	INIT_LIST_HEAD(&ui->scm_fles);
 	INIT_LIST_HEAD(&ui->ghost_node);
+	INIT_HLIST_NODE(&ui->hash);
 
 	return 0;
 }
@@ -2135,6 +2151,7 @@ static int collect_one_unixsk(void *o, ProtobufCMessage *base, struct cr_img *i)
 		list_add_tail(&ui->ghost_node, &unix_ghost_addr);
 	}
 
+	hlist_add_head(&ui->hash, &sk_info_hash[ui->ue->ino % SK_INFO_HASH_SIZE]);
 	list_add_tail(&ui->list, &unix_sockets);
 	return file_desc_add(&ui->d, ui->ue->id, &unix_desc_ops);
 }