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xen/intr: split xen_intr_isrc_lock uses

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There are actually several distinct locking domains in xen_intr.c, but
all were sharing the same lock.  Both xen_intr_port_to_isrc[] and the
x86 interrupt structures needed protection.  Split these two apart as a
precursor to splitting the architecture portions off the file.

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 834013dea2
commit ff73b1d69b
1 changed files with 34 additions and 7 deletions
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41
sys/x86/xen/xen_intr.c
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@ -73,6 +73,16 @@ __FBSDID("$FreeBSD$");
static MALLOC_DEFINE(M_XENINTR, "xen_intr", "Xen Interrupt Services");
/*
* Lock for x86-related structures. Notably modifying
* xen_intr_auto_vector_count, and allocating interrupts require this lock be
* held.
*
* ->xi_type == EVTCHN_TYPE_UNBOUND indicates a xenisrc is under control of
* this lock and operations require it be held.
*/
static struct mtx xen_intr_x86_lock;
static u_int first_evtchn_irq;
/**
@ -160,6 +170,16 @@ struct pic xen_intr_pic = {
.pic_assign_cpu = xen_intr_pic_assign_cpu,
};
/*
* Lock for interrupt core data.
*
* Modifying xen_intr_port_to_isrc[], or isrc->xi_port (implies the former)
* requires this lock be held. Any time this lock is not held, the condition
* `!xen_intr_port_to_isrc[i] || (xen_intr_port_to_isrc[i]->ix_port == i)`
* MUST be true for all values of i which are valid indicies of the array.
*
* Acquire/release operations for isrc->xi_refcount require this lock be held.
*/
static struct mtx xen_intr_isrc_lock;
static u_int xen_intr_auto_vector_count;
static struct xenisrc *xen_intr_port_to_isrc[NR_EVENT_CHANNELS];
@ -274,7 +294,7 @@ xen_intr_find_unused_isrc(enum evtchn_type type)
{
int isrc_idx;
KASSERT(mtx_owned(&xen_intr_isrc_lock), ("Evtchn isrc lock not held"));
mtx_assert(&xen_intr_x86_lock, MA_OWNED);
for (isrc_idx = 0; isrc_idx < xen_intr_auto_vector_count; isrc_idx ++) {
struct xenisrc *isrc;
@ -317,10 +337,10 @@ xen_intr_alloc_isrc(enum evtchn_type type)
unsigned int vector;
int error;
mtx_lock(&xen_intr_isrc_lock);
mtx_lock(&xen_intr_x86_lock);
isrc = xen_intr_find_unused_isrc(type);
if (isrc != NULL) {
mtx_unlock(&xen_intr_isrc_lock);
mtx_unlock(&xen_intr_x86_lock);
return (isrc);
}
@ -329,7 +349,7 @@ xen_intr_alloc_isrc(enum evtchn_type type)
warned = 1;
printf("%s: Xen interrupts exhausted.\n", __func__);
}
mtx_unlock(&xen_intr_isrc_lock);
mtx_unlock(&xen_intr_x86_lock);
return (NULL);
}
@ -339,7 +359,7 @@ xen_intr_alloc_isrc(enum evtchn_type type)
KASSERT((intr_lookup_source(vector) == NULL),
("Trying to use an already allocated vector"));
mtx_unlock(&xen_intr_isrc_lock);
mtx_unlock(&xen_intr_x86_lock);
isrc = malloc(sizeof(*isrc), M_XENINTR, M_WAITOK | M_ZERO);
isrc->xi_intsrc.is_pic = &xen_intr_pic;
isrc->xi_vector = vector;
@ -383,11 +403,16 @@ xen_intr_release_isrc(struct xenisrc *isrc)
xen_intr_port_to_isrc[isrc->xi_port] = NULL;
}
/* not reachable from xen_intr_port_to_isrc[], unlock */
mtx_unlock(&xen_intr_isrc_lock);
isrc->xi_cpu = 0;
isrc->xi_type = EVTCHN_TYPE_UNBOUND;
isrc->xi_port = INVALID_EVTCHN;
isrc->xi_cookie = NULL;
mtx_unlock(&xen_intr_isrc_lock);
mtx_lock(&xen_intr_x86_lock);
isrc->xi_type = EVTCHN_TYPE_UNBOUND;
mtx_unlock(&xen_intr_x86_lock);
return (0);
}
@ -634,6 +659,8 @@ xen_intr_init(void *dummy __unused)
mtx_init(&xen_intr_isrc_lock, "xen-irq-lock", NULL, MTX_DEF);
mtx_init(&xen_intr_x86_lock, "xen-x86-table-lock", NULL, MTX_DEF);
/*
* Set the per-cpu mask of CPU#0 to enable all, since by default all
* event channels are bound to CPU#0.