---
name: "nbd_poll2"
section: "3"
platform: "linux"
package: "libnbd"
version: "1.24.4-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/nbd_poll2"
---

# nbd\_poll2(3)

poll the handle once, with fd

## NAME

nbd\_poll2 - poll the handle once, with fd

## SYNOPSIS

```
 #include <libnbd.h>
 int nbd_poll2 (
       struct nbd_handle *h, int fd, int timeout
     );
```

## DESCRIPTION

This is the same as [**nbd\_poll**(3)](/nbd_poll/3.md), but an additional file descriptor parameter is passed.  The additional fd is also polled (using `"POLLIN"`).  One use for this is to wait for an [**eventfd**(2)](/eventfd/2.md).

## RETURN VALUE

This call returns an integer ≥ `0`.

## ERRORS

On error `-1` is returned.

Refer to "ERROR HANDLING" in [**libnbd**(3)](/libnbd/3.md) for how to get further details of the error.

The following parameters must not be NULL: `"h"`. For more information see "Non-NULL parameters" in [**libnbd**(3)](/libnbd/3.md).

## VERSION

This function first appeared in libnbd 1.16.

If you need to test if this function is available at compile time check if the following macro is defined:

```
 #define LIBNBD_HAVE_NBD_POLL2 1
```

## SEE ALSO

[**nbd\_create**(3)](/nbd_create/3.md), [**nbd\_poll**(3)](/nbd_poll/3.md), [**libnbd**(3)](/libnbd/3.md), [**eventfd**(2)](/eventfd/2.md).

## AUTHORS

Eric Blake

Richard W.M. Jones

## COPYRIGHT

Copyright Red Hat

## LICENSE

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA