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Properly protect the min/target variables from balloon_sc, not just target.

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Use their reference directly instead of going through their opaque
sysctl_data storage. It makes the locking a bit more obvious.
This commit is contained in:
jym 2011-12-26 20:26:38 +00:00
parent 633e57ef34
commit 63a89b8713
1 changed files with 30 additions and 24 deletions
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54
sys/arch/xen/xen/balloon.c
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@ -1,4 +1,4 @@
/* $NetBSD: balloon.c,v 1.11 2011/09/20 00:12:24 jym Exp $ */
/* $NetBSD: balloon.c,v 1.12 2011/12/26 20:26:38 jym Exp $ */
/*-
* Copyright (c) 2010 The NetBSD Foundation, Inc.
@ -71,7 +71,7 @@
#define BALLOONDEBUG 0
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: balloon.c,v 1.11 2011/09/20 00:12:24 jym Exp $");
__KERNEL_RCSID(0, "$NetBSD: balloon.c,v 1.12 2011/12/26 20:26:38 jym Exp $");
#include <sys/inttypes.h>
#include <sys/device.h>
@ -129,18 +129,17 @@ struct balloon_xenbus_softc {
device_t sc_dev;
struct sysctllog *sc_log;
kmutex_t balloon_mtx; /* Protects condvar and target (below) */
kmutex_t balloon_mtx; /* Protects condvar, target and res_min (below) */
kcondvar_t balloon_cv; /* Condvar variable for target (below) */
size_t balloon_target; /* Target domain reservation size in pages. */
xen_pfn_t *sc_mfn_list; /* List of MFNs passed from/to balloon */
/* Minimum amount of memory reserved by domain, in KiB */
uint64_t balloon_res_min;
xen_pfn_t *sc_mfn_list; /* List of MFNs passed from/to balloon */
pool_cache_t bpge_pool; /* pool cache for balloon page entries */
/* linked list for tracking pages used by balloon */
SLIST_HEAD(, balloon_page_entry) balloon_page_entries;
size_t balloon_num_page_entries;
/* Minimum amount of memory reserved by domain, in KiB */
uint64_t balloon_res_min;
};
static size_t xenmem_get_currentreservation(void);
@ -607,21 +606,25 @@ balloon_xenbus_watcher(struct xenbus_watch *watch, const char **vec,
unsigned int len)
{
size_t new_target;
uint64_t target_kb = balloon_xenbus_read_target();
uint64_t target_min = balloon_sc->balloon_res_min;
uint64_t target_max = BALLOON_PAGES_TO_KB(xenmem_get_maxreservation());
uint64_t target_kb, target_max, target_min;
target_kb = balloon_xenbus_read_target();
if (target_kb == 0) {
/* bogus -- just return */
return;
}
mutex_enter(&balloon_sc->balloon_mtx);
target_min = balloon_sc->balloon_res_min;
mutex_exit(&balloon_sc->balloon_mtx);
if (target_kb < target_min) {
device_printf(balloon_sc->sc_dev,
"new target %"PRIu64" is below min %"PRIu64"\n",
target_kb, target_min);
return;
}
target_max = BALLOON_PAGES_TO_KB(xenmem_get_maxreservation());
if (target_kb > target_max) {
/*
* Should not happen. Hypervisor should block balloon
@ -664,7 +667,10 @@ sysctl_kern_xen_balloon_min(SYSCTLFN_ARGS)
node = *rnode;
node.sysctl_data = &newval;
newval = *(u_quad_t *)rnode->sysctl_data;
mutex_enter(&balloon_sc->balloon_mtx);
newval = balloon_sc->balloon_res_min;
mutex_exit(&balloon_sc->balloon_mtx);
error = sysctl_lookup(SYSCTLFN_CALL(&node));
if (error || newp == NULL)
@ -678,8 +684,10 @@ sysctl_kern_xen_balloon_min(SYSCTLFN_ARGS)
return EPERM;
}
if (*(u_quad_t *)rnode->sysctl_data != newval)
atomic_swap_64((u_quad_t *)rnode->sysctl_data, newval);
mutex_enter(&balloon_sc->balloon_mtx);
if (balloon_sc->balloon_res_min != newval)
balloon_sc->balloon_res_min = newval;
mutex_exit(&balloon_sc->balloon_mtx);
return 0;
}
@ -729,8 +737,11 @@ sysctl_kern_xen_balloon_target(SYSCTLFN_ARGS)
node = *rnode;
node.sysctl_data = &newval;
/* we are just reading the value of target, no lock needed */
newval = BALLOON_PAGES_TO_KB(*(u_quad_t*)rnode->sysctl_data);
mutex_enter(&balloon_sc->balloon_mtx);
newval = BALLOON_PAGES_TO_KB(balloon_sc->balloon_target);
res_min = balloon_sc->balloon_res_min;
mutex_exit(&balloon_sc->balloon_mtx);
error = sysctl_lookup(SYSCTLFN_CALL(&node));
if (newp == NULL || error != 0) {
@ -747,7 +758,6 @@ sysctl_kern_xen_balloon_target(SYSCTLFN_ARGS)
* sorry.
*/
res_max = BALLOON_PAGES_TO_KB(xenmem_get_maxreservation());
res_min = balloon_sc->balloon_res_min;
if (newval < res_min || newval > res_max) {
#if BALLOONDEBUG
device_printf(balloon_sc->sc_dev,
@ -799,16 +809,14 @@ sysctl_kern_xen_balloon_setup(struct balloon_xenbus_softc *sc)
CTLTYPE_QUAD, "current",
SYSCTL_DESCR("Domain's current memory reservation from "
"hypervisor, in KiB."),
sysctl_kern_xen_balloon_current, 0,
NULL, 0,
sysctl_kern_xen_balloon_current, 0, NULL, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(clog, 0, &node, NULL,
CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
CTLTYPE_QUAD, "target",
SYSCTL_DESCR("Target memory reservation for domain, in KiB."),
sysctl_kern_xen_balloon_target, 0,
&sc->balloon_target, 0,
sysctl_kern_xen_balloon_target, 0, NULL, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(clog, 0, &node, NULL,
@ -816,8 +824,7 @@ sysctl_kern_xen_balloon_setup(struct balloon_xenbus_softc *sc)
CTLTYPE_QUAD, "min",
SYSCTL_DESCR("Minimum amount of memory the domain "
"reserves, in KiB."),
sysctl_kern_xen_balloon_min, 0,
&sc->balloon_res_min, 0,
sysctl_kern_xen_balloon_min, 0, NULL, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(clog, 0, &node, NULL,
@ -825,7 +832,6 @@ sysctl_kern_xen_balloon_setup(struct balloon_xenbus_softc *sc)
CTLTYPE_QUAD, "max",
SYSCTL_DESCR("Maximum amount of memory the domain "
"can use, in KiB."),
sysctl_kern_xen_balloon_max, 0,
NULL, 0,
sysctl_kern_xen_balloon_max, 0, NULL, 0,
CTL_CREATE, CTL_EOL);
}