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xen/intr: rework xen_intr_alloc_isrc() locking

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Locking for allocation was being done in xen_intr_bind_isrc(), but the
unlock was inside xen_intr_alloc_isrc().  While the lock acquisition at
the end of xen_intr_alloc_isrc() was to modify xen_intr_port_to_isrc[],
NOT allocation.  Fix this garbled (though working) locking scheme.

Now locking for allocation is strictly in xen_intr_alloc_isrc(), while
locking to modify xen_intr_port_to_isrc[] is in xen_intr_bind_isrc().

Reviewed by: royger
Differential Revision: https://reviews.freebsd.org/D30726
This commit is contained in:
Elliott Mitchell 2021-05-11 12:05:03 -07:00 committed by Roger Pau Monné
parent 09bd542d17
commit 834013dea2
1 changed files with 6 additions and 7 deletions
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13
sys/x86/xen/xen_intr.c
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@ -317,9 +317,10 @@ xen_intr_alloc_isrc(enum evtchn_type type)
unsigned int vector;
int error;
KASSERT(mtx_owned(&xen_intr_isrc_lock), ("Evtchn alloc lock not held"));
mtx_lock(&xen_intr_isrc_lock);
isrc = xen_intr_find_unused_isrc(type);
if (isrc != NULL) {
mtx_unlock(&xen_intr_isrc_lock);
return (isrc);
}
@ -328,6 +329,7 @@ xen_intr_alloc_isrc(enum evtchn_type type)
warned = 1;
printf("%s: Xen interrupts exhausted.\n", __func__);
}
mtx_unlock(&xen_intr_isrc_lock);
return (NULL);
}
@ -346,7 +348,6 @@ xen_intr_alloc_isrc(enum evtchn_type type)
if (error != 0)
panic("%s(): failed registering interrupt %u, error=%d\n",
__func__, vector, error);
mtx_lock(&xen_intr_isrc_lock);
return (isrc);
}
@ -427,16 +428,14 @@ xen_intr_bind_isrc(struct xenisrc **isrcp, evtchn_port_t local_port,
}
*port_handlep = NULL;
mtx_lock(&xen_intr_isrc_lock);
isrc = xen_intr_alloc_isrc(type);
if (isrc == NULL) {
mtx_unlock(&xen_intr_isrc_lock);
if (isrc == NULL)
return (ENOSPC);
}
isrc->xi_port = local_port;
isrc->xi_close = false;
xen_intr_port_to_isrc[local_port] = isrc;
refcount_init(&isrc->xi_refcount, 1);
mtx_lock(&xen_intr_isrc_lock);
xen_intr_port_to_isrc[isrc->xi_port] = isrc;
mtx_unlock(&xen_intr_isrc_lock);
#ifdef SMP