Santos, Jose Renato G
2006-Dec-09 04:10 UTC
[Xen-devel] [patch] new version of find_domain_by_id() without reference count [2/6]
Following Keir suggestion, this is set of patches to add a new version
of find_domain_by_id() which does not increment the domain reference
counter. This reduces the overhead and can be used by any function which
does not need to keep a domain reference beyond its current invocation,
as the rcu mechanism prevents the domain from being removed under our
feet. Of course, this can only be applied after the RCU patch posted
earlier.
Beyond adding the function the patch also replaces most invocations to
find_domain_by_id() with the new function find_domain_by_id_noref().
Only a few places needed to continue using the old function as the
reference was kept beyond the function invocation.
I only did minor tests on x86-32. Xen and dom0 boots fine and I can
create and destroy domains. But, no more exaustive tests were done. I
carefully checked if I removed all put_domain() associated with each
modified invocation of find_domain_by_id but mistakes are always
possible. It would be good to put this to some more exhaustive tests
before pushing it to the main tree. Waiting for post 3.0.4 release is
strongly suggested.
I also decomposed the patch in multiple parts so that the mantainers of
each architecture can review changes in their subtree, test and apply
them at their convenience.
This patch:
2/6: replace find_domain_by_id on acm subtree
======================================Signed-off-by: Jose Renato Santos
<jsantos@hpl.hp.com>
# HG changeset patch
# User root@lsnpsvr3.hpl.hp.com
# Node ID ac17c8457896f63da25c5458b5a76b2ab83139cd
# Parent 2301c76e27c401a04f29745024091a374d49f424
Replace find_domain_by_id() with find_domain_by_id_noref() for acm files
diff -r 2301c76e27c4 -r ac17c8457896 xen/acm/acm_core.c
--- a/xen/acm/acm_core.c Fri Dec 8 18:09:25 2006 -0800
+++ b/xen/acm/acm_core.c Fri Dec 8 18:13:10 2006 -0800
@@ -276,7 +276,7 @@ acm_init_domain_ssid(domid_t id, ssidref
acm_init_domain_ssid(domid_t id, ssidref_t ssidref)
{
struct acm_ssid_domain *ssid;
- struct domain *subj = find_domain_by_id(id);
+ struct domain *subj = find_domain_by_id_noref(id);
int ret1, ret2;
if (subj == NULL)
@@ -286,7 +286,6 @@ acm_init_domain_ssid(domid_t id, ssidref
}
if ((ssid = xmalloc(struct acm_ssid_domain)) == NULL)
{
- put_domain(subj);
return ACM_INIT_SSID_ERROR;
}
@@ -318,12 +317,10 @@ acm_init_domain_ssid(domid_t id, ssidref
printk("%s: ERROR instantiating individual ssids for domain
0x%02x.\n",
__func__, subj->domain_id);
acm_free_domain_ssid(ssid);
- put_domain(subj);
return ACM_INIT_SSID_ERROR;
}
printkd("%s: assigned domain %x the ssidref=%x.\n",
__func__, id, ssid->ssidref);
- put_domain(subj);
return ACM_OK;
}
diff -r 2301c76e27c4 -r ac17c8457896
xen/acm/acm_simple_type_enforcement_hooks.c
--- a/xen/acm/acm_simple_type_enforcement_hooks.c Fri Dec 8
18:09:25 2006 -0800
+++ b/xen/acm/acm_simple_type_enforcement_hooks.c Fri Dec 8
18:13:10 2006 -0800
@@ -206,7 +206,7 @@ ste_init_state(struct acm_ste_policy_buf
ste_rssidref = ste_rssid->ste_ssidref;
} else if (d->evtchn[port]->state == ECS_UNBOUND) {
rdomid = d->evtchn[port]->u.unbound.remote_domid;
- if ((rdom = find_domain_by_id(rdomid)) == NULL) {
+ if ((rdom = find_domain_by_id_noref(rdomid)) == NULL) {
printk("%s: Error finding domain to id %x!\n",
__func__, rdomid);
goto out;
}
@@ -214,7 +214,6 @@ ste_init_state(struct acm_ste_policy_buf
ste_rssid GET_SSIDP(ACM_SIMPLE_TYPE_ENFORCEMENT_POLICY,
(struct acm_ssid_domain
*)(rdom->ssid));
ste_rssidref = ste_rssid->ste_ssidref;
- put_domain(rdom);
} else {
spin_unlock(&d->evtchn_lock);
continue; /* port unused */
@@ -246,7 +245,7 @@ ste_init_state(struct acm_ste_policy_buf
__func__, (d->domain_id, i, sha_copy.flags,
sha_copy.domid,
(unsigned long)sha_copy.frame);
rdomid = sha_copy.domid;
- if ((rdom = find_domain_by_id(rdomid)) == NULL) {
+ if ((rdom = find_domain_by_id_noref(rdomid)) == NULL) {
printkd("%s: domain not found ERROR!\n",
__func__);
goto out;
};
@@ -254,7 +253,6 @@ ste_init_state(struct acm_ste_policy_buf
ste_rssid GET_SSIDP(ACM_SIMPLE_TYPE_ENFORCEMENT_POLICY,
(struct acm_ssid_domain
*)(rdom->ssid));
ste_rssidref = ste_rssid->ste_ssidref;
- put_domain(rdom);
if (!have_common_type(ste_ssidref, ste_rssidref)) {
printkd("%s: Policy violation in grant table
sharing domain %x -> domain %x.\n",
__func__, d->domain_id, rdomid);
@@ -510,8 +508,8 @@ ste_pre_eventchannel_unbound(domid_t id1
if (id1 == DOMID_SELF) id1 = current->domain->domain_id;
if (id2 == DOMID_SELF) id2 = current->domain->domain_id;
- subj = find_domain_by_id(id1);
- obj = find_domain_by_id(id2);
+ subj = find_domain_by_id_noref(id1);
+ obj = find_domain_by_id_noref(id2);
if ((subj == NULL) || (obj == NULL)) {
ret = ACM_ACCESS_DENIED;
goto out;
@@ -532,10 +530,6 @@ ste_pre_eventchannel_unbound(domid_t id1
ret = ACM_ACCESS_DENIED;
}
out:
- if (obj != NULL)
- put_domain(obj);
- if (subj != NULL)
- put_domain(subj);
return ret;
}
@@ -555,7 +549,7 @@ ste_pre_eventchannel_interdomain(domid_t
if (id == DOMID_SELF) id = current->domain->domain_id;
subj = current->domain;
- obj = find_domain_by_id(id);
+ obj = find_domain_by_id_noref(id);
if (obj == NULL) {
ret = ACM_ACCESS_DENIED;
goto out;
@@ -578,8 +572,6 @@ ste_pre_eventchannel_interdomain(domid_t
ret = ACM_ACCESS_DENIED;
}
out:
- if (obj != NULL)
- put_domain(obj);
return ret;
}
@@ -598,7 +590,7 @@ ste_pre_grant_map_ref (domid_t id) {
}
atomic_inc(&ste_bin_pol.gt_eval_count);
subj = current->domain;
- obj = find_domain_by_id(id);
+ obj = find_domain_by_id_noref(id);
if (share_common_type(subj, obj)) {
cache_result(subj, obj);
@@ -608,8 +600,6 @@ ste_pre_grant_map_ref (domid_t id) {
printkd("%s: ACCESS DENIED!\n", __func__);
ret = ACM_ACCESS_DENIED;
}
- if (obj != NULL)
- put_domain(obj);
return ret;
}
@@ -636,7 +626,7 @@ ste_pre_grant_setup (domid_t id) {
}
/* b) check types */
subj = current->domain;
- obj = find_domain_by_id(id);
+ obj = find_domain_by_id_noref(id);
if (share_common_type(subj, obj)) {
cache_result(subj, obj);
@@ -645,8 +635,6 @@ ste_pre_grant_setup (domid_t id) {
atomic_inc(&ste_bin_pol.gt_denied_count);
ret = ACM_ACCESS_DENIED;
}
- if (obj != NULL)
- put_domain(obj);
return ret;
}
diff -r 2301c76e27c4 -r ac17c8457896 xen/common/acm_ops.c
--- a/xen/common/acm_ops.c Fri Dec 8 18:09:25 2006 -0800
+++ b/xen/common/acm_ops.c Fri Dec 8 18:13:10 2006 -0800
@@ -108,20 +108,18 @@ long do_acm_op(int cmd, XEN_GUEST_HANDLE
ssidref = getssid.id.ssidref;
else if (getssid.get_ssid_by == ACM_GETBY_domainid)
{
- struct domain *subj find_domain_by_id(getssid.id.domainid);
- if (!subj)
- {
- rc = -ESRCH; /* domain not found */
- break;
- }
- if (subj->ssid == NULL)
- {
- put_domain(subj);
+ struct domain *subj find_domain_by_id_noref(getssid.id.domainid);
+ if (!subj)
+ {
+ rc = -ESRCH; /* domain not found */
+ break;
+ }
+ if (subj->ssid == NULL)
+ {
rc = -ESRCH;
break;
}
ssidref = ((struct acm_ssid_domain
*)(subj->ssid))->ssidref;
- put_domain(subj);
}
else
{
@@ -145,20 +143,18 @@ long do_acm_op(int cmd, XEN_GUEST_HANDLE
ssidref1 = getdecision.id1.ssidref;
else if (getdecision.get_decision_by1 == ACM_GETBY_domainid)
{
- struct domain *subj find_domain_by_id(getdecision.id1.domainid);
- if (!subj)
- {
- rc = -ESRCH; /* domain not found */
- break;
- }
- if (subj->ssid == NULL)
- {
- put_domain(subj);
+ struct domain *subj
find_domain_by_id_noref(getdecision.id1.domainid);
+ if (!subj)
+ {
+ rc = -ESRCH; /* domain not found */
+ break;
+ }
+ if (subj->ssid == NULL)
+ {
rc = -ESRCH;
break;
}
ssidref1 = ((struct acm_ssid_domain
*)(subj->ssid))->ssidref;
- put_domain(subj);
}
else
{
@@ -169,7 +165,7 @@ long do_acm_op(int cmd, XEN_GUEST_HANDLE
ssidref2 = getdecision.id2.ssidref;
else if (getdecision.get_decision_by2 == ACM_GETBY_domainid)
{
- struct domain *subj find_domain_by_id(getdecision.id2.domainid);
+ struct domain *subj
find_domain_by_id_noref(getdecision.id2.domainid);
if (!subj)
{
rc = -ESRCH; /* domain not found */
@@ -177,12 +173,10 @@ long do_acm_op(int cmd, XEN_GUEST_HANDLE
}
if (subj->ssid == NULL)
{
- put_domain(subj);
rc = -ESRCH;
break;
}
ssidref2 = ((struct acm_ssid_domain
*)(subj->ssid))->ssidref;
- put_domain(subj);
}
else
{
diff -r 2301c76e27c4 -r ac17c8457896 xen/include/acm/acm_hooks.h
--- a/xen/include/acm/acm_hooks.h Fri Dec 8 18:09:25 2006 -0800
+++ b/xen/include/acm/acm_hooks.h Fri Dec 8 18:13:10 2006 -0800
@@ -241,7 +241,7 @@ static inline int acm_pre_domctl(struct
__func__);
return -EACCES;
}
- d = find_domain_by_id(op->domain);
+ d = find_domain_by_id_noref(op->domain);
if (d != NULL) {
*ssid = d->ssid; /* save for post destroy when d is gone */
if (*ssid == NULL) {
@@ -252,7 +252,6 @@ static inline int acm_pre_domctl(struct
}
d->ssid = NULL; /* make sure it''s not used any more */
/* no policy-specific hook */
- put_domain(d);
ret = 0;
}
break;
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