From: Kay Sievers <kay@vrfy.org>
Date: Sat, 28 Dec 2013 17:29:05 +0000 (+0100)
Subject: limit the amount of request for a reply a connection can issue
X-Git-Tag: upstream/0.20140120.123719~79
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=4044c9cdc1bd3a6ef963a38c4ebac690f6c6a71d;p=platform%2Fcore%2Fsystem%2Fkdbus-bus.git

limit the amount of request for a reply a connection can issue
---

diff --git a/connection.c b/connection.c
index d1e61f0..aa0fdd3 100644
--- a/connection.c
+++ b/connection.c
@@ -90,8 +90,8 @@ struct kdbus_conn_reply_entry {
 static void kdbus_conn_reply_entry_free(struct kdbus_conn_reply_entry *reply)
 {
 	atomic_dec(&reply->conn->reply_count);
-	kdbus_conn_unref(reply->conn);
 	list_del(&reply->entry);
+	kdbus_conn_unref(reply->conn);
 	kfree(reply);
 }
 
@@ -758,6 +758,12 @@ int kdbus_conn_kmsg_send(struct kdbus_ep *ep,
 		struct kdbus_conn_reply_entry *reply;
 		struct timespec ts;
 
+		if (atomic_read(&conn_src->reply_count) >
+		    KDBUS_CONN_MAX_REQUESTS_PENDING) {
+			ret = -EMLINK;
+			goto exit_unref;
+		}
+
 		reply = kzalloc(sizeof(*reply), GFP_KERNEL);
 		if (!reply) {
 			ret = -ENOMEM;
@@ -766,7 +772,6 @@ int kdbus_conn_kmsg_send(struct kdbus_ep *ep,
 
 		INIT_LIST_HEAD(&reply->entry);
 		reply->conn = kdbus_conn_ref(conn_dst);
-		atomic_inc(&reply->conn->reply_count);
 		reply->cookie = msg->cookie;
 
 		/* calculate the deadline based on the current time */
@@ -775,6 +780,7 @@ int kdbus_conn_kmsg_send(struct kdbus_ep *ep,
 
 		mutex_lock(&conn_src->lock);
 		list_add(&reply->entry, &conn_src->reply_list);
+		atomic_inc(&reply->conn->reply_count);
 		mutex_unlock(&conn_src->lock);
 
 		kdbus_conn_timeout_schedule_scan(conn_dst);
diff --git a/connection.h b/connection.h
index 0a31209..261804e 100644
--- a/connection.h
+++ b/connection.h
@@ -33,8 +33,8 @@
  * @names_queue_list:	Well-known names this connection waits for
  * @reply_list:		List of connections this connection expects
  * 			a reply from.
- * @reply_count:	Number of replies expected by others to be
- * 			received from this connection
+ * @reply_count:	Number of requests this connection has issued, and
+ * 			waits for replies from the peer
  * @names:		Number of owned well-known names
  * @work:		Support for poll()
  * @timer:		Message reply timeout handling
diff --git a/internal.h b/internal.h
index 03f09ae..8daffc7 100644
--- a/internal.h
+++ b/internal.h
@@ -15,24 +15,44 @@
 
 #include "kdbus.h"
 
-/* limits enforced by the interfaces */
-#define KDBUS_MSG_MAX_SIZE		SZ_8K		/* maximum size of message header and items */
-#define KDBUS_MSG_MAX_ITEMS		128		/* maximum number of message items */
-#define KDBUS_MSG_MAX_FDS		256		/* maximum number of passed file descriptors */
-#define KDBUS_MSG_MAX_PAYLOAD_VEC_SIZE	SZ_8M		/* maximum message payload size */
+/* maximum size of message header and items */
+#define KDBUS_MSG_MAX_SIZE		SZ_8K
 
-#define KDBUS_NAME_MAX_LEN		255		/* maximum length of well-known bus name */
+/* maximum number of message items */
+#define KDBUS_MSG_MAX_ITEMS		128
 
-#define KDBUS_MAKE_MAX_LEN		63		/* maximum length of bus, ns, ep name */
-#define KDBUS_MAKE_MAX_SIZE		SZ_32K		/* maximum size of make data */
+/* maximum number of passed file descriptors */
+#define KDBUS_MSG_MAX_FDS		256
 
-#define KDBUS_HELLO_MAX_SIZE		SZ_32K		/* maximum size of hello data */
-#define KDBUS_MATCH_MAX_SIZE		SZ_32K		/* maximum size of match data */
-#define KDBUS_POLICY_MAX_SIZE		SZ_32K		/* maximum size of policy data */
+/* maximum message payload size */
+#define KDBUS_MSG_MAX_PAYLOAD_VEC_SIZE	SZ_2M
 
-#define KDBUS_CONN_MAX_MSGS		64		/* maximum number of queued messages per connection */
-#define KDBUS_CONN_MAX_NAMES		64		/* maximum number of well-known names */
-#define KDBUS_CONN_MAX_ALLOCATED_BYTES	SZ_64K		/* maximum number of allocated bytes on the bus */
+/* maximum length of well-known bus name */
+#define KDBUS_NAME_MAX_LEN		255
+
+/* maximum length of bus, ns, ep name */
+#define KDBUS_MAKE_MAX_LEN		63
+
+/* maximum size of make data */
+#define KDBUS_MAKE_MAX_SIZE		SZ_32K
+
+/* maximum size of hello data */
+#define KDBUS_HELLO_MAX_SIZE		SZ_32K
+
+/* maximum size of match data */
+#define KDBUS_MATCH_MAX_SIZE		SZ_32K
+
+/* maximum size of policy data */
+#define KDBUS_POLICY_MAX_SIZE		SZ_32K
+
+/* maximum number of queued messages per connection */
+#define KDBUS_CONN_MAX_MSGS		64
+
+/* maximum number of well-known names */
+#define KDBUS_CONN_MAX_NAMES		64
+
+/* maximum number of queud requests waiting ot a reply */
+#define KDBUS_CONN_MAX_REQUESTS_PENDING	64
 
 /* all exported addresses are 64 bit */
 #define KDBUS_PTR(addr) ((void __user *)(uintptr_t)(addr))
diff --git a/kdbus.h b/kdbus.h
index c59bdd8..81f0d8e 100644
--- a/kdbus.h
+++ b/kdbus.h
@@ -789,6 +789,8 @@ enum kdbus_ioctl_type {
  * 			refused to send as KDBUS_MSG_PAYLOAD_MEMFD.
  * @EMFILE:		Too many file descriptors have been supplied with a
  * 			message.
+ * @EMLINK:		Too many requests from this connection to other peers
+ *			are queued and waiting for a reply
  * @EMSGSIZE:		The supplied data is larger than the allowed maximum
  * 			size.
  * @ENAMETOOLONG:	The requested name is larger than the allowed maximum