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A Xen PV frontend communicates its state to the PV backend by writing to the 'state' key in the frontend area in xenstore. It is therefore necessary for a XenDevice implementation to be notified whenever the value of this key changes. This patch adds code to do this as follows: - an 'fd handler' is registered on the libxenstore handle which will be triggered whenever a 'watch' event occurs - primitives are added to xen-bus-helper to add or remove watch events - a list of Notifier objects is added to XenBus to provide a mechanism to call the appropriate 'watch handler' when its associated event occurs The xen-block implementation is extended with a 'frontend_changed' method, which calls as-yet stub 'connect' and 'disconnect' functions when the relevant frontend state transitions occur. A subsequent patch will supply a full implementation for these functions. Signed-off-by: Paul Durrant <paul.durrant@citrix.com> Reviewed-by: Anthony Perard <anthony.perard@citrix.com> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
46 lines
1.9 KiB
C
46 lines
1.9 KiB
C
/*
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* Copyright (c) 2018 Citrix Systems Inc.
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#ifndef HW_XEN_BUS_HELPER_H
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#define HW_XEN_BUS_HELPER_H
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#include "hw/xen/xen_common.h"
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const char *xs_strstate(enum xenbus_state state);
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void xs_node_create(struct xs_handle *xsh, xs_transaction_t tid,
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const char *node, struct xs_permissions perms[],
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unsigned int nr_perms, Error **errp);
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void xs_node_destroy(struct xs_handle *xsh, xs_transaction_t tid,
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const char *node, Error **errp);
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/* Write to node/key unless node is empty, in which case write to key */
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void xs_node_vprintf(struct xs_handle *xsh, xs_transaction_t tid,
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const char *node, const char *key, Error **errp,
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const char *fmt, va_list ap)
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GCC_FMT_ATTR(6, 0);
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void xs_node_printf(struct xs_handle *xsh, xs_transaction_t tid,
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const char *node, const char *key, Error **errp,
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const char *fmt, ...)
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GCC_FMT_ATTR(6, 7);
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/* Read from node/key unless node is empty, in which case read from key */
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int xs_node_vscanf(struct xs_handle *xsh, xs_transaction_t tid,
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const char *node, const char *key, Error **errp,
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const char *fmt, va_list ap);
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int xs_node_scanf(struct xs_handle *xsh, xs_transaction_t tid,
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const char *node, const char *key, Error **errp,
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const char *fmt, ...);
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/* Watch node/key unless node is empty, in which case watch key */
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void xs_node_watch(struct xs_handle *xsh, const char *node, const char *key,
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char *token, Error **errp);
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void xs_node_unwatch(struct xs_handle *xsh, const char *node, const char *key,
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const char *token, Error **errp);
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#endif /* HW_XEN_BUS_HELPER_H */
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