1 files changed, 148 insertions, 72 deletions

diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
index 9951297b242..957a0b98a5d 100644
--- a/drivers/vhost/tcm_vhost.c
+++ b/drivers/vhost/tcm_vhost.c
@@ -60,14 +60,22 @@ enum {
 	VHOST_SCSI_VQ_IO = 2,
 };
 
+/*
+ * VIRTIO_RING_F_EVENT_IDX seems broken. Not sure the bug is in
+ * kernel but disabling it helps.
+ * TODO: debug and remove the workaround.
+ */
+enum {
+	VHOST_SCSI_FEATURES = VHOST_FEATURES & (~VIRTIO_RING_F_EVENT_IDX)
+};
+
 #define VHOST_SCSI_MAX_TARGET	256
 #define VHOST_SCSI_MAX_VQ	128
 
 struct vhost_scsi {
 	/* Protected by vhost_scsi->dev.mutex */
-	struct tcm_vhost_tpg *vs_tpg[VHOST_SCSI_MAX_TARGET];
+	struct tcm_vhost_tpg **vs_tpg;
 	char vs_vhost_wwpn[TRANSPORT_IQN_LEN];
-	bool vs_endpoint;
 
 	struct vhost_dev dev;
 	struct vhost_virtqueue vqs[VHOST_SCSI_MAX_VQ];
@@ -570,9 +578,27 @@ static void tcm_vhost_submission_work(struct work_struct *work)
 	}
 }
 
+static void vhost_scsi_send_bad_target(struct vhost_scsi *vs,
+	struct vhost_virtqueue *vq, int head, unsigned out)
+{
+	struct virtio_scsi_cmd_resp __user *resp;
+	struct virtio_scsi_cmd_resp rsp;
+	int ret;
+
+	memset(&rsp, 0, sizeof(rsp));
+	rsp.response = VIRTIO_SCSI_S_BAD_TARGET;
+	resp = vq->iov[out].iov_base;
+	ret = __copy_to_user(resp, &rsp, sizeof(rsp));
+	if (!ret)
+		vhost_add_used_and_signal(&vs->dev, vq, head, 0);
+	else
+		pr_err("Faulted on virtio_scsi_cmd_resp\n");
+}
+
 static void vhost_scsi_handle_vq(struct vhost_scsi *vs,
 	struct vhost_virtqueue *vq)
 {
+	struct tcm_vhost_tpg **vs_tpg;
 	struct virtio_scsi_cmd_req v_req;
 	struct tcm_vhost_tpg *tv_tpg;
 	struct tcm_vhost_cmd *tv_cmd;
@@ -581,8 +607,16 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs,
 	int head, ret;
 	u8 target;
 
-	/* Must use ioctl VHOST_SCSI_SET_ENDPOINT */
-	if (unlikely(!vs->vs_endpoint))
+	/*
+	 * We can handle the vq only after the endpoint is setup by calling the
+	 * VHOST_SCSI_SET_ENDPOINT ioctl.
+	 *
+	 * TODO: Check that we are running from vhost_worker which acts
+	 * as read-side critical section for vhost kind of RCU.
+	 * See the comments in struct vhost_virtqueue in drivers/vhost/vhost.h
+	 */
+	vs_tpg = rcu_dereference_check(vq->private_data, 1);
+	if (!vs_tpg)
 		return;
 
 	mutex_lock(&vq->mutex);
@@ -652,23 +686,11 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs,
 
 		/* Extract the tpgt */
 		target = v_req.lun[1];
-		tv_tpg = vs->vs_tpg[target];
+		tv_tpg = ACCESS_ONCE(vs_tpg[target]);
 
 		/* Target does not exist, fail the request */
 		if (unlikely(!tv_tpg)) {
-			struct virtio_scsi_cmd_resp __user *resp;
-			struct virtio_scsi_cmd_resp rsp;
-
-			memset(&rsp, 0, sizeof(rsp));
-			rsp.response = VIRTIO_SCSI_S_BAD_TARGET;
-			resp = vq->iov[out].iov_base;
-			ret = __copy_to_user(resp, &rsp, sizeof(rsp));
-			if (!ret)
-				vhost_add_used_and_signal(&vs->dev,
-							  vq, head, 0);
-			else
-				pr_err("Faulted on virtio_scsi_cmd_resp\n");
-
+			vhost_scsi_send_bad_target(vs, vq, head, out);
 			continue;
 		}
 
@@ -681,22 +703,13 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs,
 		if (IS_ERR(tv_cmd)) {
 			vq_err(vq, "vhost_scsi_allocate_cmd failed %ld\n",
 					PTR_ERR(tv_cmd));
-			break;
+			goto err_cmd;
 		}
 		pr_debug("Allocated tv_cmd: %p exp_data_len: %d, data_direction"
 			": %d\n", tv_cmd, exp_data_len, data_direction);
 
 		tv_cmd->tvc_vhost = vs;
 		tv_cmd->tvc_vq = vq;
-
-		if (unlikely(vq->iov[out].iov_len !=
-				sizeof(struct virtio_scsi_cmd_resp))) {
-			vq_err(vq, "Expecting virtio_scsi_cmd_resp, got %zu"
-				" bytes, out: %d, in: %d\n",
-				vq->iov[out].iov_len, out, in);
-			break;
-		}
-
 		tv_cmd->tvc_resp = vq->iov[out].iov_base;
 
 		/*
@@ -716,7 +729,7 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs,
 				" exceeds SCSI_MAX_VARLEN_CDB_SIZE: %d\n",
 				scsi_command_size(tv_cmd->tvc_cdb),
 				TCM_VHOST_MAX_CDB_SIZE);
-			break; /* TODO */
+			goto err_free;
 		}
 		tv_cmd->tvc_lun = ((v_req.lun[2] << 8) | v_req.lun[3]) & 0x3FFF;
 
@@ -729,7 +742,7 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs,
 					data_direction == DMA_TO_DEVICE);
 			if (unlikely(ret)) {
 				vq_err(vq, "Failed to map iov to sgl\n");
-				break; /* TODO */
+				goto err_free;
 			}
 		}
 
@@ -750,6 +763,13 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs,
 	}
 
 	mutex_unlock(&vq->mutex);
+	return;
+
+err_free:
+	vhost_scsi_free_cmd(tv_cmd);
+err_cmd:
+	vhost_scsi_send_bad_target(vs, vq, head, out);
+	mutex_unlock(&vq->mutex);
 }
 
 static void vhost_scsi_ctl_handle_kick(struct vhost_work *work)
@@ -771,6 +791,20 @@ static void vhost_scsi_handle_kick(struct vhost_work *work)
 	vhost_scsi_handle_vq(vs, vq);
 }
 
+static void vhost_scsi_flush_vq(struct vhost_scsi *vs, int index)
+{
+	vhost_poll_flush(&vs->dev.vqs[index].poll);
+}
+
+static void vhost_scsi_flush(struct vhost_scsi *vs)
+{
+	int i;
+
+	for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)
+		vhost_scsi_flush_vq(vs, i);
+	vhost_work_flush(&vs->dev, &vs->vs_completion_work);
+}
+
 /*
  * Called from vhost_scsi_ioctl() context to walk the list of available
  * tcm_vhost_tpg with an active struct tcm_vhost_nexus
@@ -781,8 +815,10 @@ static int vhost_scsi_set_endpoint(
 {
 	struct tcm_vhost_tport *tv_tport;
 	struct tcm_vhost_tpg *tv_tpg;
+	struct tcm_vhost_tpg **vs_tpg;
+	struct vhost_virtqueue *vq;
+	int index, ret, i, len;
 	bool match = false;
-	int index, ret;
 
 	mutex_lock(&vs->dev.mutex);
 	/* Verify that ring has been setup correctly. */
@@ -794,6 +830,15 @@ static int vhost_scsi_set_endpoint(
 		}
 	}
 
+	len = sizeof(vs_tpg[0]) * VHOST_SCSI_MAX_TARGET;
+	vs_tpg = kzalloc(len, GFP_KERNEL);
+	if (!vs_tpg) {
+		mutex_unlock(&vs->dev.mutex);
+		return -ENOMEM;
+	}
+	if (vs->vs_tpg)
+		memcpy(vs_tpg, vs->vs_tpg, len);
+
 	mutex_lock(&tcm_vhost_mutex);
 	list_for_each_entry(tv_tpg, &tcm_vhost_list, tv_tpg_list) {
 		mutex_lock(&tv_tpg->tv_tpg_mutex);
@@ -808,14 +853,15 @@ static int vhost_scsi_set_endpoint(
 		tv_tport = tv_tpg->tport;
 
 		if (!strcmp(tv_tport->tport_name, t->vhost_wwpn)) {
-			if (vs->vs_tpg[tv_tpg->tport_tpgt]) {
+			if (vs->vs_tpg && vs->vs_tpg[tv_tpg->tport_tpgt]) {
 				mutex_unlock(&tv_tpg->tv_tpg_mutex);
 				mutex_unlock(&tcm_vhost_mutex);
 				mutex_unlock(&vs->dev.mutex);
+				kfree(vs_tpg);
 				return -EEXIST;
 			}
 			tv_tpg->tv_tpg_vhost_count++;
-			vs->vs_tpg[tv_tpg->tport_tpgt] = tv_tpg;
+			vs_tpg[tv_tpg->tport_tpgt] = tv_tpg;
 			smp_mb__after_atomic_inc();
 			match = true;
 		}
@@ -826,12 +872,27 @@ static int vhost_scsi_set_endpoint(
 	if (match) {
 		memcpy(vs->vs_vhost_wwpn, t->vhost_wwpn,
 		       sizeof(vs->vs_vhost_wwpn));
-		vs->vs_endpoint = true;
+		for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
+			vq = &vs->vqs[i];
+			/* Flushing the vhost_work acts as synchronize_rcu */
+			mutex_lock(&vq->mutex);
+			rcu_assign_pointer(vq->private_data, vs_tpg);
+			vhost_init_used(vq);
+			mutex_unlock(&vq->mutex);
+		}
 		ret = 0;
 	} else {
 		ret = -EEXIST;
 	}
 
+	/*
+	 * Act as synchronize_rcu to make sure access to
+	 * old vs->vs_tpg is finished.
+	 */
+	vhost_scsi_flush(vs);
+	kfree(vs->vs_tpg);
+	vs->vs_tpg = vs_tpg;
+
 	mutex_unlock(&vs->dev.mutex);
 	return ret;
 }
@@ -842,6 +903,8 @@ static int vhost_scsi_clear_endpoint(
 {
 	struct tcm_vhost_tport *tv_tport;
 	struct tcm_vhost_tpg *tv_tpg;
+	struct vhost_virtqueue *vq;
+	bool match = false;
 	int index, ret, i;
 	u8 target;
 
@@ -850,20 +913,26 @@ static int vhost_scsi_clear_endpoint(
 	for (index = 0; index < vs->dev.nvqs; ++index) {
 		if (!vhost_vq_access_ok(&vs->vqs[index])) {
 			ret = -EFAULT;
-			goto err;
+			goto err_dev;
 		}
 	}
+
+	if (!vs->vs_tpg) {
+		mutex_unlock(&vs->dev.mutex);
+		return 0;
+	}
+
 	for (i = 0; i < VHOST_SCSI_MAX_TARGET; i++) {
 		target = i;
-
 		tv_tpg = vs->vs_tpg[target];
 		if (!tv_tpg)
 			continue;
 
+		mutex_lock(&tv_tpg->tv_tpg_mutex);
 		tv_tport = tv_tpg->tport;
 		if (!tv_tport) {
 			ret = -ENODEV;
-			goto err;
+			goto err_tpg;
 		}
 
 		if (strcmp(tv_tport->tport_name, t->vhost_wwpn)) {
@@ -872,20 +941,58 @@ static int vhost_scsi_clear_endpoint(
 				tv_tport->tport_name, tv_tpg->tport_tpgt,
 				t->vhost_wwpn, t->vhost_tpgt);
 			ret = -EINVAL;
-			goto err;
+			goto err_tpg;
 		}
 		tv_tpg->tv_tpg_vhost_count--;
 		vs->vs_tpg[target] = NULL;
-		vs->vs_endpoint = false;
+		match = true;
+		mutex_unlock(&tv_tpg->tv_tpg_mutex);
 	}
+	if (match) {
+		for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
+			vq = &vs->vqs[i];
+			/* Flushing the vhost_work acts as synchronize_rcu */
+			mutex_lock(&vq->mutex);
+			rcu_assign_pointer(vq->private_data, NULL);
+			mutex_unlock(&vq->mutex);
+		}
+	}
+	/*
+	 * Act as synchronize_rcu to make sure access to
+	 * old vs->vs_tpg is finished.
+	 */
+	vhost_scsi_flush(vs);
+	kfree(vs->vs_tpg);
+	vs->vs_tpg = NULL;
 	mutex_unlock(&vs->dev.mutex);
+
 	return 0;
 
-err:
+err_tpg:
+	mutex_unlock(&tv_tpg->tv_tpg_mutex);
+err_dev:
 	mutex_unlock(&vs->dev.mutex);
 	return ret;
 }
 
+static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
+{
+	if (features & ~VHOST_SCSI_FEATURES)
+		return -EOPNOTSUPP;
+
+	mutex_lock(&vs->dev.mutex);
+	if ((features & (1 << VHOST_F_LOG_ALL)) &&
+	    !vhost_log_access_ok(&vs->dev)) {
+		mutex_unlock(&vs->dev.mutex);
+		return -EFAULT;
+	}
+	vs->dev.acked_features = features;
+	smp_wmb();
+	vhost_scsi_flush(vs);
+	mutex_unlock(&vs->dev.mutex);
+	return 0;
+}
+
 static int vhost_scsi_open(struct inode *inode, struct file *f)
 {
 	struct vhost_scsi *s;
@@ -926,37 +1033,6 @@ static int vhost_scsi_release(struct inode *inode, struct file *f)
 	return 0;
 }
 
-static void vhost_scsi_flush_vq(struct vhost_scsi *vs, int index)
-{
-	vhost_poll_flush(&vs->dev.vqs[index].poll);
-}
-
-static void vhost_scsi_flush(struct vhost_scsi *vs)
-{
-	int i;
-
-	for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)
-		vhost_scsi_flush_vq(vs, i);
-}
-
-static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
-{
-	if (features & ~VHOST_FEATURES)
-		return -EOPNOTSUPP;
-
-	mutex_lock(&vs->dev.mutex);
-	if ((features & (1 << VHOST_F_LOG_ALL)) &&
-	    !vhost_log_access_ok(&vs->dev)) {
-		mutex_unlock(&vs->dev.mutex);
-		return -EFAULT;
-	}
-	vs->dev.acked_features = features;
-	smp_wmb();
-	vhost_scsi_flush(vs);
-	mutex_unlock(&vs->dev.mutex);
-	return 0;
-}
-
 static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl,
 				unsigned long arg)
 {
@@ -987,7 +1063,7 @@ static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl,
 			return -EFAULT;
 		return 0;
 	case VHOST_GET_FEATURES:
-		features = VHOST_FEATURES;
+		features = VHOST_SCSI_FEATURES;
 		if (copy_to_user(featurep, &features, sizeof features))
 			return -EFAULT;
 		return 0;