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xen/intr: add reference counts to event channels

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Add a reference count to xenisrc. This is required for implementation of
unmap-notifications in the grant table userspace device (gntdev). We need to
hold a reference to the event channel port, in case the user deallocates the
port before we send the notification.

Submitted by:		jaggi
Reviewed by:		royger
Differential review:	https://reviews.freebsd.org/D7429
This commit is contained in:
Roger Pau Monné 2016-10-31 13:00:53 +00:00
parent b2fd6999db
commit 0f4d7d9fd7
2 changed files with 49 additions and 4 deletions
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41
sys/x86/xen/xen_intr.c
View File

@ -45,6 +45,7 @@ __FBSDID("$FreeBSD$");
#include <sys/interrupt.h>
#include <sys/pcpu.h>
#include <sys/smp.h>
#include <sys/refcount.h>
#include <vm/vm.h>
#include <vm/pmap.h>
@ -128,6 +129,7 @@ struct xenisrc {
u_int xi_activehi:1;
u_int xi_edgetrigger:1;
u_int xi_masked:1;
volatile u_int xi_refcount;
};
static void xen_intr_suspend(struct pic *);
@ -343,10 +345,8 @@ xen_intr_release_isrc(struct xenisrc *isrc)
{
mtx_lock(&xen_intr_isrc_lock);
if (isrc->xi_intsrc.is_handlers != 0) {
mtx_unlock(&xen_intr_isrc_lock);
return (EBUSY);
}
KASSERT(isrc->xi_intsrc.is_handlers == 0,
("Release called, but xenisrc still in use"));
evtchn_mask_port(isrc->xi_port);
evtchn_clear_port(isrc->xi_port);
@ -417,6 +417,7 @@ xen_intr_bind_isrc(struct xenisrc **isrcp, evtchn_port_t local_port,
}
isrc->xi_port = local_port;
xen_intr_port_to_isrc[local_port] = isrc;
refcount_init(&isrc->xi_refcount, 1);
mtx_unlock(&xen_intr_isrc_lock);
/* Assign the opaque handler (the event channel port) */
@ -1508,6 +1509,13 @@ xen_intr_unbind(xen_intr_handle_t *port_handlep)
if (isrc == NULL)
return;
mtx_lock(&xen_intr_isrc_lock);
if (refcount_release(&isrc->xi_refcount) == 0) {
mtx_unlock(&xen_intr_isrc_lock);
return;
}
mtx_unlock(&xen_intr_isrc_lock);
if (isrc->xi_cookie != NULL)
intr_remove_handler(isrc->xi_cookie);
xen_intr_release_isrc(isrc);
@ -1563,6 +1571,31 @@ xen_intr_add_handler(device_t dev, driver_filter_t filter,
return (error);
}
int
xen_intr_get_evtchn_from_port(evtchn_port_t port, xen_intr_handle_t *handlep)
{
if (!is_valid_evtchn(port) || port >= NR_EVENT_CHANNELS)
return (EINVAL);
if (handlep == NULL) {
return (EINVAL);
}
mtx_lock(&xen_intr_isrc_lock);
if (xen_intr_port_to_isrc[port] == NULL) {
mtx_unlock(&xen_intr_isrc_lock);
return (EINVAL);
}
refcount_acquire(&xen_intr_port_to_isrc[port]->xi_refcount);
mtx_unlock(&xen_intr_isrc_lock);
/* Assign the opaque handler (the event channel port) */
*handlep = &xen_intr_port_to_isrc[port]->xi_vector;
return (0);
}
#ifdef DDB
static const char *
xen_intr_print_type(enum evtchn_type type)

12
sys/xen/xen_intr.h
View File

@ -263,4 +263,16 @@ int xen_intr_add_handler(device_t dev, driver_filter_t filter,
driver_intr_t handler, void *arg, enum intr_type flags,
xen_intr_handle_t handle);
/**
* Get a reference to an event channel port
*
* \param port Event channel port to which we get a reference.
* \param handlep Pointer to an opaque handle used to manage this
* registration.
*
* \returns 0 on success, otherwise an errno.
*/
int xen_intr_get_evtchn_from_port(evtchn_port_t port,
xen_intr_handle_t *handlep);
#endif /* _XEN_INTR_H_ */