kdbus: per message number accouting

gistfile1.c

diff --git a/connection.c b/connection.c
index ec0f6b0..c135419 100644
--- a/connection.c
+++ b/connection.c
@@ -640,7 +640,9 @@ static int kdbus_conn_quota(struct kdbus_conn *c, struct kdbus_user *u,
 
 	/* per user-accounting is expensive, so we keep state small */
 	BUILD_BUG_ON(sizeof(quota->memory) != 4);
+	BUILD_BUG_ON(sizeof(quota->msgs) != 1);
 	BUILD_BUG_ON(sizeof(quota->fds) != 1);
+	BUILD_BUG_ON(KDBUS_CONN_MAX_MSGS_PER_USER > U8_MAX);
 	BUILD_BUG_ON(KDBUS_CONN_MAX_FDS_PER_USER > U8_MAX);
 
 	if (u->id >= c->n_quota) {
@@ -661,7 +663,8 @@ static int kdbus_conn_quota(struct kdbus_conn *c, struct kdbus_user *u,
 
 	if (available < quota->memory ||
 	    available - quota->memory < memory ||
-	    quota->memory + memory > U32_MAX)
+	    quota->memory + memory > U32_MAX ||
+	    quota->msgs >= KDBUS_CONN_MAX_MSGS_PER_USER)
 		return -ENOBUFS;
 
 	if (quota->fds + fds < quota->fds ||
@@ -670,6 +673,7 @@ static int kdbus_conn_quota(struct kdbus_conn *c, struct kdbus_user *u,
 
 	quota->memory += memory;
 	quota->fds += fds;
+	quota->msgs++;
 	return 0;
 }
 
diff --git a/connection.h b/connection.h
index ca3b97b..1a5e7f9 100644
--- a/connection.h
+++ b/connection.h
@@ -33,10 +33,12 @@
 /**
  * struct kdbus_quota - per user quota state
  * @memory:		total amount of memory in target pool
+ * @msgs:		total number of messages in target pool
  * @fds:		total number of fds in target queue
  */
 struct kdbus_quota {
 	uint32_t memory;
+	uint8_t msgs;
 	uint8_t fds;
 };
 
diff --git a/limits.h b/limits.h
index 13e0129..f6adccc 100644
--- a/limits.h
+++ b/limits.h
@@ -49,6 +49,9 @@
 /* maximum number of queued messages in a connection */
 #define KDBUS_CONN_MAX_MSGS			256
 
+/* maximum number of queued messages from the same indvidual user */
+#define KDBUS_CONN_MAX_MSGS_PER_USER		64
+
 /* maximum number of inflight fds in a target queue per user */
 #define KDBUS_CONN_MAX_FDS_PER_USER		16
 
diff --git a/queue.c b/queue.c
index eb6be02..fe25a01 100644
--- a/queue.c
+++ b/queue.c
@@ -150,6 +150,9 @@ void kdbus_queue_entry_remove(struct kdbus_conn *conn,
 
 		entry->user = kdbus_user_unref(entry->user);
 
+		if (!WARN_ON(quota->msgs == 0))
+			quota->msgs--;
+
 		n = kdbus_pool_slice_size(entry->slice);
 		if (!WARN_ON(quota->memory < n))
 			quota->memory -= n;