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xen/gntalloc,gntdev: Add unmap notify ioctl

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This ioctl allows the users of a shared page to be notified when
the other end exits abnormally.

[v2: updated description in structs]
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Daniel De Graaf 2011-02-03 12:19:04 -05:00 • committed by Konrad Rzeszutek Wilk
parent dd3140588d
commit bdc612dc69
4 changed files with 182 additions and 1 deletions
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32
include/xen/gntalloc.h
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@ -47,4 +47,36 @@ struct ioctl_gntalloc_dealloc_gref {
/* Number of references to unmap */
uint32_t count;
};
/*
* Sets up an unmap notification within the page, so that the other side can do
* cleanup if this side crashes. Required to implement cross-domain robust
* mutexes or close notification on communication channels.
*
* Each mapped page only supports one notification; multiple calls referring to
* the same page overwrite the previous notification. You must clear the
* notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
* to occur.
*/
#define IOCTL_GNTALLOC_SET_UNMAP_NOTIFY \
_IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntalloc_unmap_notify))
struct ioctl_gntalloc_unmap_notify {
/* IN parameters */
/* Offset in the file descriptor for a byte within the page (same as
* used in mmap). If using UNMAP_NOTIFY_CLEAR_BYTE, this is the byte to
* be cleared. Otherwise, it can be any byte in the page whose
* notification we are adjusting.
*/
uint64_t index;
/* Action(s) to take on unmap */
uint32_t action;
/* Event channel to notify */
uint32_t event_channel_port;
};
/* Clear (set to zero) the byte specified by index */
#define UNMAP_NOTIFY_CLEAR_BYTE 0x1
/* Send an interrupt on the indicated event channel */
#define UNMAP_NOTIFY_SEND_EVENT 0x2
#endif /* __LINUX_PUBLIC_GNTALLOC_H__ */