File 25835-adjust-rcu-lock-domain.patch of Package xen.openSUSE_12.1_Update
# HG changeset patch
# User Jan Beulich <jbeulich@suse.com>
# Date 1347033492 -7200
# Node ID c70d70d85306b3e4a0538353be131100c5ee38d5
# Parent 0376c85caaf34fe3cc8c3327f7a1d9ecd6f070b4
adjust a few RCU domain locking calls
x86's do_physdev_op() had a case where the locking was entirely
superfluous. Its physdev_map_pirq() further had a case where the lock
was being obtained too early, needlessly complicating early exit paths.
Grant table code had two open coded instances of
rcu_lock_target_domain_by_id(), and a third code section could be
consolidated by using the newly introduced helper function.
The memory hypercall code had two more instances of open coding
rcu_lock_target_domain_by_id(), but note that here this is not just
cleanup, but also fixes an error return path in memory_exchange() to
actually return an error.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>
--- a/xen/arch/x86/physdev.c
+++ b/xen/arch/x86/physdev.c
@@ -93,15 +93,11 @@ static int physdev_hvm_map_pirq(
static int physdev_map_pirq(struct physdev_map_pirq *map)
{
- struct domain *d;
+ struct domain *d = current->domain;
int pirq, irq, ret = 0;
struct msi_info _msi;
void *map_data = NULL;
- ret = rcu_lock_target_domain_by_id(map->domid, &d);
- if ( ret )
- return ret;
-
if ( map->domid == DOMID_SELF && is_hvm_domain(d) )
{
/*
@@ -109,14 +105,15 @@ static int physdev_map_pirq(struct physd
* calls back into itself and deadlocks on hvm_domain.irq_lock.
*/
if ( !is_hvm_pv_evtchn_domain(d) )
- {
- ret = -EINVAL;
- goto free_domain;
- }
- ret = physdev_hvm_map_pirq(d, map);
- goto free_domain;
+ return -EINVAL;
+
+ return physdev_hvm_map_pirq(d, map);
}
+ ret = rcu_lock_target_domain_by_id(map->domid, &d);
+ if ( ret )
+ return ret;
+
if ( !IS_PRIV_FOR(current->domain, d) )
{
ret = -EPERM;
@@ -607,10 +604,8 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_H
}
case PHYSDEVOP_get_free_pirq: {
struct physdev_get_free_pirq out;
- struct domain *d;
+ struct domain *d = v->domain;
- d = rcu_lock_current_domain();
-
ret = -EFAULT;
if ( copy_from_guest(&out, arg, 1) != 0 )
break;
@@ -622,7 +617,6 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_H
ret = copy_to_guest(arg, &out, 1) ? -EFAULT : 0;
- rcu_unlock_domain(d);
break;
}
default:
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -24,7 +24,7 @@
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
-#include <xen/config.h>
+#include <xen/err.h>
#include <xen/iocap.h>
#include <xen/lib.h>
#include <xen/sched.h>
@@ -172,6 +172,30 @@ static int __get_paged_frame(unsigned lo
return rc;
}
+static struct domain *gt_lock_target_domain_by_id(domid_t dom)
+{
+ struct domain *d;
+ int rc = GNTST_general_error;
+
+ switch ( rcu_lock_target_domain_by_id(dom, &d) )
+ {
+ case 0:
+ return d;
+
+ case -ESRCH:
+ gdprintk(XENLOG_INFO, "Bad domid %d.\n", dom);
+ rc = GNTST_bad_domain;
+ break;
+
+ case -EPERM:
+ rc = GNTST_permission_denied;
+ break;
+ }
+
+ ASSERT(rc < 0 && -rc <= MAX_ERRNO);
+ return ERR_PTR(rc);
+}
+
static inline int
__get_maptrack_handle(
struct grant_table *t)
@@ -1216,7 +1240,6 @@ gnttab_setup_table(
struct domain *d;
int i;
unsigned long gmfn;
- domid_t dom;
if ( count != 1 )
return -EINVAL;
@@ -1236,25 +1259,11 @@ gnttab_setup_table(
goto out1;
}
- dom = op.dom;
- if ( dom == DOMID_SELF )
+ d = gt_lock_target_domain_by_id(op.dom);
+ if ( IS_ERR(d) )
{
- d = rcu_lock_current_domain();
- }
- else
- {
- if ( unlikely((d = rcu_lock_domain_by_id(dom)) == NULL) )
- {
- gdprintk(XENLOG_INFO, "Bad domid %d.\n", dom);
- op.status = GNTST_bad_domain;
- goto out1;
- }
-
- if ( unlikely(!IS_PRIV_FOR(current->domain, d)) )
- {
- op.status = GNTST_permission_denied;
- goto out2;
- }
+ op.status = PTR_ERR(d);
+ goto out1;
}
if ( xsm_grant_setup(current->domain, d) )
@@ -1309,7 +1318,6 @@ gnttab_query_size(
{
struct gnttab_query_size op;
struct domain *d;
- domid_t dom;
int rc;
if ( count != 1 )
@@ -1321,25 +1329,11 @@ gnttab_query_size(
return -EFAULT;
}
- dom = op.dom;
- if ( dom == DOMID_SELF )
+ d = gt_lock_target_domain_by_id(op.dom);
+ if ( IS_ERR(d) )
{
- d = rcu_lock_current_domain();
- }
- else
- {
- if ( unlikely((d = rcu_lock_domain_by_id(dom)) == NULL) )
- {
- gdprintk(XENLOG_INFO, "Bad domid %d.\n", dom);
- op.status = GNTST_bad_domain;
- goto query_out;
- }
-
- if ( unlikely(!IS_PRIV_FOR(current->domain, d)) )
- {
- op.status = GNTST_permission_denied;
- goto query_out_unlock;
- }
+ op.status = PTR_ERR(d);
+ goto query_out;
}
rc = xsm_grant_query_size(current->domain, d);
@@ -2179,7 +2173,6 @@ gnttab_get_status_frames(XEN_GUEST_HANDL
struct grant_table *gt;
uint64_t gmfn;
int i;
- int rc;
if ( count != 1 )
return -EINVAL;
@@ -2191,15 +2184,10 @@ gnttab_get_status_frames(XEN_GUEST_HANDL
return -EFAULT;
}
- rc = rcu_lock_target_domain_by_id(op.dom, &d);
- if ( rc < 0 )
+ d = gt_lock_target_domain_by_id(op.dom);
+ if ( IS_ERR(d) )
{
- if ( rc == -ESRCH )
- op.status = GNTST_bad_domain;
- else if ( rc == -EPERM )
- op.status = GNTST_permission_denied;
- else
- op.status = GNTST_general_error;
+ op.status = PTR_ERR(d);
goto out1;
}
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -310,22 +310,9 @@ static long memory_exchange(XEN_GUEST_HA
out_chunk_order = exch.in.extent_order - exch.out.extent_order;
}
- if ( likely(exch.in.domid == DOMID_SELF) )
- {
- d = rcu_lock_current_domain();
- }
- else
- {
- if ( (d = rcu_lock_domain_by_id(exch.in.domid)) == NULL )
- goto fail_early;
-
- if ( !IS_PRIV_FOR(current->domain, d) )
- {
- rcu_unlock_domain(d);
- rc = -EPERM;
- goto fail_early;
- }
- }
+ rc = rcu_lock_target_domain_by_id(exch.in.domid, &d);
+ if ( rc )
+ goto fail_early;
memflags |= MEMF_bits(domain_clamp_alloc_bitsize(
d,
@@ -556,20 +543,8 @@ long do_memory_op(unsigned long cmd, XEN
&& (reservation.mem_flags & XENMEMF_populate_on_demand) )
args.memflags |= MEMF_populate_on_demand;
- if ( likely(reservation.domid == DOMID_SELF) )
- {
- d = rcu_lock_current_domain();
- }
- else
- {
- if ( (d = rcu_lock_domain_by_id(reservation.domid)) == NULL )
- return start_extent;
- if ( !IS_PRIV_FOR(current->domain, d) )
- {
- rcu_unlock_domain(d);
- return start_extent;
- }
- }
+ if ( unlikely(rcu_lock_target_domain_by_id(reservation.domid, &d)) )
+ return start_extent;
args.domain = d;
rc = xsm_memory_adjust_reservation(current->domain, d);
