[CRIU] [PATCH 07/10] kcmp: files -- Add fd_kid_epoll_lookup helper

[Cyrill Gorcunov]

So we will use it to lookup for target file in epoll queue.

Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
 criu/file-ids.c         | 12 ++++++++++++
 criu/include/file-ids.h |  6 +++++-
 criu/include/kcmp-ids.h |  4 ++++
 criu/kcmp-ids.c         | 51 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/criu/file-ids.c b/criu/file-ids.c
index 36973cbdd939..6e68eebe2cac 100644
--- a/criu/file-ids.c
+++ b/criu/file-ids.c
@@ -111,3 +111,15 @@ int fd_id_generate(pid_t pid, FdinfoEntry *fe, struct fd_parms *p)
 	fe->id = id;
 	return new_id;
 }
+
+struct kid_elem *fd_kid_epoll_lookup(pid_t pid, unsigned int genid,
+				     kcmp_epoll_slot_t *slot)
+{
+	struct kid_elem e = {
+		.pid	= pid,
+		.genid	= genid,
+		.idx	= -1,	/* A stub, not needed for epoll */
+	};
+
+	return kid_epoll_lookup(&fd_tree, &e, slot);
+}
diff --git a/criu/include/file-ids.h b/criu/include/file-ids.h
index e796f403a57e..71acf6a1f242 100644
--- a/criu/include/file-ids.h
+++ b/criu/include/file-ids.h
@@ -5,6 +5,7 @@
 
 #include "common/compiler.h"
 #include "rbtree.h"
+#include "kcmp.h"
 
 #include "images/fdinfo.pb-c.h"
 
@@ -13,10 +14,13 @@
 
 struct fdinfo_entry;
 struct stat;
-
+struct kid_elem;
 struct fd_parms;
+
 extern int fd_id_generate(pid_t pid, FdinfoEntry *fe, struct fd_parms *p);
 extern int fd_id_generate_special(struct fd_parms *p, u32 *id);
+extern struct kid_elem *fd_kid_epoll_lookup(pid_t pid, unsigned int genid,
+					    kcmp_epoll_slot_t *slot);
 
 /*
  * The gen_id thing is used to optimize the comparison of shared files.
diff --git a/criu/include/kcmp-ids.h b/criu/include/kcmp-ids.h
index 37e2398db206..b1f7a1970bb8 100644
--- a/criu/include/kcmp-ids.h
+++ b/criu/include/kcmp-ids.h
@@ -29,4 +29,8 @@ struct kid_elem {
 extern uint32_t kid_generate_gen(struct kid_tree *tree,
 				 struct kid_elem *elem, int *new_id);
 
+extern struct kid_elem *kid_epoll_lookup(struct kid_tree *tree,
+					 struct kid_elem *elem,
+					 kcmp_epoll_slot_t *slot);
+
 #endif /* __CR_KCMP_IDS_H__ */
diff --git a/criu/kcmp-ids.c b/criu/kcmp-ids.c
index 5b91fb66b886..79bd86f9140b 100644
--- a/criu/kcmp-ids.c
+++ b/criu/kcmp-ids.c
@@ -154,3 +154,54 @@ uint32_t kid_generate_gen(struct kid_tree *tree,
 	return e->subid;
 
 }
+
+static struct kid_elem *kid_epoll_lookup_sub(struct kid_tree *tree,
+					     struct kid_entry *e,
+					     struct kid_elem *elem,
+					     kcmp_epoll_slot_t *slot)
+{
+	struct rb_node *node = e->subtree_root.rb_node;
+
+	BUG_ON(!node);
+
+	while (node) {
+		struct kid_entry *this = rb_entry(node, struct kid_entry, subtree_node);
+		int ret = syscall(SYS_kcmp, this->elem.pid, elem->pid, KCMP_EPOLL_TFD,
+				this->elem.idx, slot);
+
+		if (ret == 1)
+			node = node->rb_left;
+		else if (ret == 2)
+			node = node->rb_right;
+		else if (ret == 0)
+			return &this->elem;
+		else {
+			pr_perror("kcmp failed: pid (%d %d) type %u idx (%u %u)",
+				  this->elem.pid, elem->pid, KCMP_EPOLL_TFD,
+				  this->elem.idx, elem->idx);
+			return NULL;
+		}
+	}
+
+	return NULL;
+}
+
+struct kid_elem *kid_epoll_lookup(struct kid_tree *tree,
+				  struct kid_elem *elem,
+				  kcmp_epoll_slot_t *slot)
+{
+	struct rb_node *node = tree->root.rb_node;
+
+	while (node) {
+		struct kid_entry *this = rb_entry(node, struct kid_entry, node);
+
+		if (elem->genid < this->elem.genid)
+			node = node->rb_left;
+		else if (elem->genid > this->elem.genid)
+			node = node->rb_right;
+		else
+			return kid_epoll_lookup_sub(tree, this, elem, slot);
+	}
+
+	return NULL;
+}
-- 
2.7.4