eventfd_ctx_read
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## Name

eventfd_ctx_read — Reads the eventfd counter or wait if it is zero.

## Synopsis

`ssize_t eventfd_ctx_read (` | struct eventfd_ctx * ctx,
| int no_wait,
| __u64 * cnt`)`;

## Arguments

`ctx`

  [in] Pointer to eventfd context.

`no_wait`

  [in] Different from zero if the operation should not block.

`cnt`

  [out] Pointer to the 64-bit counter value.

## Description

Returns `0` if successful, or the following error codes:

-EAGAIN : The operation would have blocked but `no_wait` was non-zero. -ERESTARTSYS : A signal interrupted the wait operation.

If `no_wait` is zero, the function might sleep until the eventfd internal counter becomes greater than zero.

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