peer: drop support for PEEK

We have no compelling usecase for PEEK support at the moment. Drop it for now to allow us to simplify the logic quite a bit. Receiving the same message several times (which PEEK allowed) has counterintuitive semantics in particular due to different fd numbers being used each time and due to the accounting of handles. Signed-off-by: Tom Gundersen <teg@jklm.no>
bus1 · Mar 9, 2017 · 53daeb3 · 53daeb3
1 parent 733d7c0
commit 53daeb3
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Showing 4 changed files with 33 additions and 46 deletions.
diff --git a/include/uapi/linux/bus1.h b/include/uapi/linux/bus1.h
@@ -74,9 +74,8 @@ struct bus1_cmd_send {
 } __attribute__((__aligned__(8)));
 
 enum {
-	BUS1_RECV_FLAG_PEEK					= 1ULL <<  0,
-	BUS1_RECV_FLAG_SEED					= 1ULL <<  1,
-	BUS1_RECV_FLAG_INSTALL_FDS				= 1ULL <<  2,
+	BUS1_RECV_FLAG_SEED					= 1ULL <<  0,
+	BUS1_RECV_FLAG_INSTALL_FDS				= 1ULL <<  1,
 };
 
 enum {

diff --git a/ipc/bus1/message.c b/ipc/bus1/message.c
@@ -470,15 +470,13 @@ void bus1_message_stage(struct bus1_message *m, struct bus1_tx *tx)
  *
  * This installs the payload FDs and handles of @message into the receiving
  * peer and the calling process. Handles are always installed, FDs are only
- * installed if explicitly requested via @param.
+ * installed if explicitly requested via @inst_fds.
  *
  * Return: 0 on success, negative error code on failure.
  */
-int bus1_message_install(struct bus1_message *m, struct bus1_cmd_recv *param)
+int bus1_message_install(struct bus1_message *m, bool inst_fds)
 {
 	size_t i, j, n, size, offset, n_handles = 0, n_fds = 0;
-	const bool inst_fds = param->flags & BUS1_RECV_FLAG_INSTALL_FDS;
-	const bool peek = param->flags & BUS1_RECV_FLAG_PEEK;
 	struct bus1_peer *peer = m->qnode.owner;
 	struct bus1_handle *h;
 	struct bus1_flist *e;
@@ -557,15 +555,8 @@ int bus1_message_install(struct bus1_message *m, struct bus1_cmd_recv *param)
 	}
 
 	/* charge resources */
-	if (peek) {
-		r = bus1_user_charge(&peer->user->limits.n_handles,
-				     &peer->data.limits.n_handles, n_handles);
-		if (r < 0)
-			goto exit;
-	} else {
-		WARN_ON(n_handles < m->n_handles_charge);
-		m->n_handles_charge -= n_handles;
-	}
+	WARN_ON(n_handles < m->n_handles_charge);
+	m->n_handles_charge -= n_handles;
 
 	/* publish pool slice */
 	mutex_lock(&peer->data.lock);

diff --git a/ipc/bus1/message.h b/ipc/bus1/message.h
@@ -106,7 +106,7 @@ struct bus1_message *bus1_factory_instantiate(struct bus1_factory *f,
 
 void bus1_message_free(struct kref *k);
 void bus1_message_stage(struct bus1_message *m, struct bus1_tx *tx);
-int bus1_message_install(struct bus1_message *m, struct bus1_cmd_recv *param);
+int bus1_message_install(struct bus1_message *m, bool inst_fds);
 
 /**
  * bus1_message_ref() - acquire object reference

diff --git a/ipc/bus1/peer.c b/ipc/bus1/peer.c
@@ -908,7 +908,6 @@ static int bus1_peer_ioctl_send(struct bus1_peer *peer,
 }
 
 static struct bus1_queue_node *bus1_peer_peek(struct bus1_peer *peer,
-					      struct bus1_cmd_recv *param,
 					      bool *morep)
 {
 	struct bus1_queue_node *qnode;
@@ -918,14 +917,6 @@ static struct bus1_queue_node *bus1_peer_peek(struct bus1_peer *peer,
 
 	lockdep_assert_held(&peer->local.lock);
 
-	if (unlikely(param->flags & BUS1_RECV_FLAG_SEED)) {
-		if (!peer->local.seed)
-			return ERR_PTR(-EAGAIN);
-
-		*morep = false;
-		return &peer->local.seed->qnode;
-	}
-
 	mutex_lock(&peer->data.lock);
 	while ((qnode = bus1_queue_peek(&peer->data.queue, morep))) {
 		switch (bus1_queue_node_get_type(qnode)) {
@@ -962,7 +953,7 @@ static struct bus1_queue_node *bus1_peer_peek(struct bus1_peer *peer,
 			continue;
 		}
 
-		if (!m && !(param->flags & BUS1_RECV_FLAG_PEEK))
+		if (!m)
 			bus1_queue_remove(&peer->data.queue, &peer->waitq,
 					  qnode);
 
@@ -988,17 +979,25 @@ static int bus1_peer_ioctl_recv(struct bus1_peer *peer,
 
 	if (copy_from_user(&param, (void __user *)arg, sizeof(param)))
 		return -EFAULT;
-	if (unlikely(param.flags & ~(BUS1_RECV_FLAG_PEEK |
-				     BUS1_RECV_FLAG_SEED |
+	if (unlikely(param.flags & ~(BUS1_RECV_FLAG_SEED |
 				     BUS1_RECV_FLAG_INSTALL_FDS)))
 		return -EINVAL;
 
 	mutex_lock(&peer->local.lock);
 
-	qnode = bus1_peer_peek(peer, &param, &more);
-	if (IS_ERR(qnode)) {
-		r = PTR_ERR(qnode);
-		goto exit;
+	if (unlikely(param.flags & BUS1_RECV_FLAG_SEED)) {
+		if (!peer->local.seed) {
+			r = -EAGAIN;
+			goto exit;
+		}
+
+		qnode = &peer->local.seed->qnode;
+	} else {
+		qnode = bus1_peer_peek(peer, &more);
+		if (IS_ERR(qnode)) {
+			r = PTR_ERR(qnode);
+			goto exit;
+		}
 	}
 
 	type = bus1_queue_node_get_type(qnode);
@@ -1012,7 +1011,8 @@ static int bus1_peer_ioctl_recv(struct bus1_peer *peer,
 			goto exit;
 		}
 
-		r = bus1_message_install(m, &param);
+		r = bus1_message_install(m,
+				param.flags & BUS1_RECV_FLAG_INSTALL_FDS);
 		if (r < 0)
 			goto exit;
 
@@ -1024,17 +1024,15 @@ static int bus1_peer_ioctl_recv(struct bus1_peer *peer,
 		param.msg.n_handles = m->n_handles;
 		param.msg.n_fds = m->n_files;
 
-		if (likely(!(param.flags & BUS1_RECV_FLAG_PEEK))) {
-			if (unlikely(param.flags & BUS1_RECV_FLAG_SEED)) {
-				peer->local.seed = NULL;
-			} else {
-				mutex_lock(&peer->data.lock);
-				bus1_queue_remove(&peer->data.queue,
-						  &peer->waitq, qnode);
-				mutex_unlock(&peer->data.lock);
-			}
-			bus1_message_unref(m);
+		if (unlikely(param.flags & BUS1_RECV_FLAG_SEED)) {
+			peer->local.seed = NULL;
+		} else {
+			mutex_lock(&peer->data.lock);
+			bus1_queue_remove(&peer->data.queue,
+					  &peer->waitq, qnode);
+			mutex_unlock(&peer->data.lock);
 		}
+		bus1_message_unref(m);
 		break;
 	case BUS1_MSG_NODE_DESTROY:
 	case BUS1_MSG_NODE_RELEASE:
@@ -1049,8 +1047,7 @@ static int bus1_peer_ioctl_recv(struct bus1_peer *peer,
 		param.msg.n_handles = 0;
 		param.msg.n_fds = 0;
 
-		if (likely(!(param.flags & BUS1_RECV_FLAG_PEEK)))
-			bus1_handle_unref(h);
+		bus1_handle_unref(h);
 		break;
 	case BUS1_MSG_NONE:
 	default: