io\_uring\_buf\_ring\_available(3) liburing Manual io\_uring\_buf\_ring\_available(3)

# [NAME](#NAME)

io\_uring\_buf\_ring\_available - return number of unconsumed provided ring buffer entries

# [SYNOPSIS](#SYNOPSIS)

```
#include <liburing.h>
```

```
int io_uring_buf_ring_available(struct io_uring *ring,
                                struct io_uring_buf_ring *br,
                                unsigned short bgid);
```

# [DESCRIPTION](#DESCRIPTION)

The [**io\_uring\_buf\_ring\_available**(3)](/man/os/liburing/io_uring_buf_ring_available.3) helper returns the number of unconsumed (by the kernel) entries in the *br* provided buffer group belonging to the io\_uring *ring* and identified by the buffer group ID *bgid.*

Since the head of the provided buffer ring is only visible to the kernel, it's impossible to otherwise know how many unconsumed entries exist in the given provided buffer ring. This function query the kernel to return that number. Available since kernel 6.8.

# [NOTES](#NOTES)

The returned number of entries reflect the amount of unconsumed entries at the time that it was queried. If inflight IO exists that may consume provided buffers from this buffer group, then the returned value is inherently racy.

# [RETURN VALUE](#RETURN_VALUE)

Returns the number of unconsumed entries on success, which may be 0. In case of error, may return **-ENOENT** if the specified buffer group doesn't exist, or **-EINVAL** if the buffer group isn't of the correct type, or if the kernel doesn't support this feature.

# [SEE ALSO](#SEE_ALSO)

[**io\_uring\_register\_buf\_ring**(3)](/man/os/liburing/io_uring_register_buf_ring.3), [**io\_uring\_buf\_ring\_add**(3)](/man/os/liburing/io_uring_buf_ring_add.3), [**io\_uring\_buf\_ring\_cq\_advance**(3)](/man/os/liburing/io_uring_buf_ring_cq_advance.3)

January 11, 2024 liburing-2.6

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Document: io_uring_buf_ring_available(3) from liburing 2.15-r4 (Chainguard OS)
Source: https://github.com/axboe/liburing.git