1 files changed, 97 insertions, 3 deletions

diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 2a2e9e4e7593..95559811d6cc 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -94,6 +94,7 @@
 #define TCMU_GLOBAL_MAX_BLOCKS_DEF (512 * 1024)
 
 static u8 tcmu_kern_cmd_reply_supported;
+static u8 tcmu_netlink_blocked;
 
 static struct device *tcmu_root_device;
 
@@ -255,6 +256,92 @@ MODULE_PARM_DESC(global_max_data_area_mb,
 		 "Max MBs allowed to be allocated to all the tcmu device's "
 		 "data areas.");
 
+static int tcmu_get_block_netlink(char *buffer,
+				  const struct kernel_param *kp)
+{
+	return sprintf(buffer, "%s\n", tcmu_netlink_blocked ?
+		       "blocked" : "unblocked");
+}
+
+static int tcmu_set_block_netlink(const char *str,
+				  const struct kernel_param *kp)
+{
+	int ret;
+	u8 val;
+
+	ret = kstrtou8(str, 0, &val);
+	if (ret < 0)
+		return ret;
+
+	if (val > 1) {
+		pr_err("Invalid block netlink value %u\n", val);
+		return -EINVAL;
+	}
+
+	tcmu_netlink_blocked = val;
+	return 0;
+}
+
+static const struct kernel_param_ops tcmu_block_netlink_op = {
+	.set = tcmu_set_block_netlink,
+	.get = tcmu_get_block_netlink,
+};
+
+module_param_cb(block_netlink, &tcmu_block_netlink_op, NULL, S_IWUSR | S_IRUGO);
+MODULE_PARM_DESC(block_netlink, "Block new netlink commands.");
+
+static int tcmu_fail_netlink_cmd(struct tcmu_nl_cmd *nl_cmd)
+{
+	struct tcmu_dev *udev = nl_cmd->udev;
+
+	if (!tcmu_netlink_blocked) {
+		pr_err("Could not reset device's netlink interface. Netlink is not blocked.\n");
+		return -EBUSY;
+	}
+
+	if (nl_cmd->cmd != TCMU_CMD_UNSPEC) {
+		pr_debug("Aborting nl cmd %d on %s\n", nl_cmd->cmd, udev->name);
+		nl_cmd->status = -EINTR;
+		list_del(&nl_cmd->nl_list);
+		complete(&nl_cmd->complete);
+	}
+	return 0;
+}
+
+static int tcmu_set_reset_netlink(const char *str,
+				  const struct kernel_param *kp)
+{
+	struct tcmu_nl_cmd *nl_cmd, *tmp_cmd;
+	int ret;
+	u8 val;
+
+	ret = kstrtou8(str, 0, &val);
+	if (ret < 0)
+		return ret;
+
+	if (val != 1) {
+		pr_err("Invalid reset netlink value %u\n", val);
+		return -EINVAL;
+	}
+
+	mutex_lock(&tcmu_nl_cmd_mutex);
+	list_for_each_entry_safe(nl_cmd, tmp_cmd, &tcmu_nl_cmd_list, nl_list) {
+		ret = tcmu_fail_netlink_cmd(nl_cmd);
+		if (ret)
+			break;
+	}
+	mutex_unlock(&tcmu_nl_cmd_mutex);
+
+	return ret;
+}
+
+static const struct kernel_param_ops tcmu_reset_netlink_op = {
+	.set = tcmu_set_reset_netlink,
+};
+
+module_param_cb(reset_netlink, &tcmu_reset_netlink_op, NULL, S_IWUSR);
+MODULE_PARM_DESC(reset_netlink, "Reset netlink commands.");
+
 /* multicast group */
 enum tcmu_multicast_groups {
 	TCMU_MCGRP_CONFIG,
@@ -303,8 +390,9 @@ static int tcmu_genl_cmd_done(struct genl_info *info, int completed_cmd)
 	}
 	list_del(&nl_cmd->nl_list);
 
-	pr_debug("%s genl cmd done got id %d curr %d done %d rc %d\n",
-		 udev->name, dev_id, nl_cmd->cmd, completed_cmd, rc);
+	pr_debug("%s genl cmd done got id %d curr %d done %d rc %d stat %d\n",
+		 udev->name, dev_id, nl_cmd->cmd, completed_cmd, rc,
+		 nl_cmd->status);
 
 	if (nl_cmd->cmd != completed_cmd) {
 		pr_err("Mismatched commands on %s (Expecting reply for %d. Current %d).\n",
@@ -1547,6 +1635,13 @@ static int tcmu_init_genl_cmd_reply(struct tcmu_dev *udev, int cmd)
 
 	mutex_lock(&tcmu_nl_cmd_mutex);
 
+	if (tcmu_netlink_blocked) {
+		mutex_unlock(&tcmu_nl_cmd_mutex);
+		pr_warn("Failing nl cmd %d on %s. Interface is blocked.\n", cmd,
+			udev->name);
+		return -EAGAIN;
+	}
+
 	if (nl_cmd->cmd != TCMU_CMD_UNSPEC) {
 		mutex_unlock(&tcmu_nl_cmd_mutex);
 		pr_warn("netlink cmd %d already executing on %s\n",
@@ -1583,7 +1678,6 @@ static int tcmu_wait_genl_cmd_reply(struct tcmu_dev *udev)
 	mutex_lock(&tcmu_nl_cmd_mutex);
 	nl_cmd->cmd = TCMU_CMD_UNSPEC;
 	ret = nl_cmd->status;
-	nl_cmd->status = 0;
 	mutex_unlock(&tcmu_nl_cmd_mutex);
 
 	return ret;