Re: [Xen-devel] [PATCH XEN v6 25/32] tools/libs/gnttab: Extensive updates to API documentation.

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, Dec 03, 2015 at 11:22:22AM +0000, Ian Campbell wrote:
[...]
> + * connection, connected, etc).
> + *
> + * Both ends are permitted to modify (including clear) their
> + * respective status bytes and to signal the event channel themselves
> + * from userspace.
> + *
> + * Depending on the mechanisms which have been registered an
> + * application may receive a shutdown notification as:
> + *
> + *   - An event channel notification on a dedicated event channel
> + *   - Observation of the other ends's status byte being cleared
> + *     (whether in response to an explicit notification or in the
> + *     course of normal operation).
> + *
> + * The mechanism should be defined as part of the specific ring
> + * protocol.
> + *
> + * Upon receiving notification of their peer's shutdown an application
> + * is expected to teardown any resources (and in particular any grant
> + * mappings) in a timely manner.
> + *
> + * NOTE: this protocol is intended to allow for better error behaviour
> + * and recovery between two cooperating peers. It does not cover the
> + * case of a malivious peer who may continue to hold resources open.

"malicious"

> + */
> +
> +/*
>   * Grant Table Interface (making use of grants from other domains)
>   */
>  
>  typedef struct xengntdev_handle xengnttab_handle;
>  
>  /*
> - * Note:
> - * After fork a child process must not use any opened xc gnttab
> - * handle inherited from their parent. They must open a new handle if
> - * they want to interact with xc.
> + * Returns a handle onto the grant table driver.  Logs errors.
> + *
> + * Note: After fork a child process must not use any opened gnttab
> + * handle inherited from their parent, more access any grant mapped
> + * areas associated with that handle.
> + *

And this could use the same cloexec trick as you do in other patch for
privcmd.

Wei.

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