Mailing List Archive

# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1276261262 -3600
# Node ID 2ad3a78c8cd66b335e7f3a2782826c5780358ee2
# Parent 94793113faef36e58e4960cba1c9f9f8bb6f60d8
tmem: Fix domain lifecycle synchronisation.

Obtaining a domain reference count is neither necessary nor
sufficient. Instead we simply check whether a domain is already dying
when it first becomes a client of tmem. If it is not then we will
correctly clean up later via tmem_destroy() called from domain_kill().

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
xen-unstable changeset: 21596:04e81a65d27e
xen-unstable date: Thu Jun 10 22:39:52 2010 +0100
---
xen/common/tmem.c | 18 ++++++++++++------
xen/common/tmem_xen.c | 2 +-
xen/include/xen/tmem_xen.h | 27 +++++++++++++++------------
3 files changed, 28 insertions(+), 19 deletions(-)

diff -r 94793113faef -r 2ad3a78c8cd6 xen/common/tmem.c
--- a/xen/common/tmem.c Fri Jun 11 14:00:36 2010 +0100
+++ b/xen/common/tmem.c Fri Jun 11 14:01:02 2010 +0100
@@ -1170,17 +1170,19 @@ static client_t *client_create(cli_id_t
if ( client == NULL )
{
printk("failed... out of memory\n");
- return NULL;
+ goto fail;
}
memset(client,0,sizeof(client_t));
if ( (client->tmh = tmh_client_init(cli_id)) == NULL )
{
printk("failed... can't allocate host-dependent part of client\n");
- if ( client )
- tmh_free_infra(client);
- return NULL;
- }
- tmh_set_client_from_id(client, client->tmh, cli_id);
+ goto fail;
+ }
+ if ( !tmh_set_client_from_id(client, client->tmh, cli_id) )
+ {
+ printk("failed... can't set client\n");
+ goto fail;
+ }
client->cli_id = cli_id;
#ifdef __i386__
client->compress = 0;
@@ -1202,6 +1204,10 @@ static client_t *client_create(cli_id_t
client->succ_eph_gets = 0; client->succ_pers_gets = 0;
printk("ok\n");
return client;
+
+ fail:
+ tmh_free_infra(client);
+ return NULL;
}

static void client_free(client_t *client)
diff -r 94793113faef -r 2ad3a78c8cd6 xen/common/tmem_xen.c
--- a/xen/common/tmem_xen.c Fri Jun 11 14:00:36 2010 +0100
+++ b/xen/common/tmem_xen.c Fri Jun 11 14:01:02 2010 +0100
@@ -338,10 +338,10 @@ EXPORT tmh_client_t *tmh_client_init(cli

EXPORT void tmh_client_destroy(tmh_client_t *tmh)
{
+ ASSERT(tmh->domain->is_dying);
#ifndef __i386__
xmem_pool_destroy(tmh->persistent_pool);
#endif
- put_domain(tmh->domain);
tmh->domain = NULL;
}

diff -r 94793113faef -r 2ad3a78c8cd6 xen/include/xen/tmem_xen.h
--- a/xen/include/xen/tmem_xen.h Fri Jun 11 14:00:36 2010 +0100
+++ b/xen/include/xen/tmem_xen.h Fri Jun 11 14:01:02 2010 +0100
@@ -302,9 +302,6 @@ extern tmh_client_t *tmh_client_init(cli
extern tmh_client_t *tmh_client_init(cli_id_t);
extern void tmh_client_destroy(tmh_client_t *);

-/* we don't need to take a reference to the domain here as we hold
- * one for the entire life of the client, so use rcu_lock_domain_by_id
- * variant instead of get_domain_by_id() */
static inline struct client *tmh_client_from_cli_id(cli_id_t cli_id)
{
struct client *c;
@@ -333,15 +330,21 @@ static inline tmh_cli_ptr_t *tmh_get_cli
return current->domain;
}

-static inline void tmh_set_client_from_id(struct client *client,
- tmh_client_t *tmh, cli_id_t cli_id)
-{
- /* here we DO want to take/hold a reference to the domain as
- * this routine should be called exactly once when the client is created;
- * the matching put_domain is in tmh_client_destroy */
- struct domain *d = get_domain_by_id(cli_id);
- d->tmem = client;
- tmh->domain = d;
+static inline bool_t tmh_set_client_from_id(
+ struct client *client, tmh_client_t *tmh, cli_id_t cli_id)
+{
+ struct domain *d = rcu_lock_domain_by_id(cli_id);
+ bool_t rc = 0;
+ if ( d == NULL )
+ return 0;
+ if ( !d->is_dying )
+ {
+ d->tmem = client;
+ tmh->domain = d;
+ rc = 1;
+ }
+ rcu_unlock_domain(d);
+ return rc;
}

static inline bool_t tmh_current_is_privileged(void)

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