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Missed bits in preventing circular locking dependency between target_mutex and scst_mutex

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git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@752 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Vladislav Bolkhovitin
2009-04-06 11:19:07 +00:00
parent fb22b12769
commit 426234630f
1 changed files with 43 additions and 36 deletions
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79
iscsi-scst/kernel/session.c
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@@ -126,34 +126,14 @@ void sess_enable_reinstated_sess(struct iscsi_session *sess)
return;
}
/* target_mutex supposed to be locked */
static void session_reinstate(struct iscsi_session *old_sess,
struct iscsi_session *new_sess)
{
TRACE_ENTRY();
TRACE_MGMT_DBG("Reinstating sess %p with SID %llx (old %p, SID %llx)",
new_sess, new_sess->sid, old_sess, old_sess->sid);
new_sess->sess_reinstating = 1;
old_sess->sess_reinst_successor = new_sess;
scst_set_initial_UA(new_sess->scst_sess,
SCST_LOAD_SENSE(scst_sense_nexus_loss_UA));
target_del_session(old_sess->target, old_sess, 0);
TRACE_EXIT();
return;
}
/* target_mgmt_mutex supposed to be locked */
int session_add(struct iscsi_target *target,
struct iscsi_kern_session_info *info)
{
struct iscsi_session *new_sess, *session, *old_sess;
struct iscsi_session *new_sess, *sess, *old_sess;
int err = 0;
union iscsi_sid sid;
bool reinstatement = false;
TRACE_MGMT_DBG("Adding session SID %llx", info->sid);
@@ -163,8 +143,8 @@ int session_add(struct iscsi_target *target,
mutex_lock(&target->target_mutex);
session = session_lookup(target, info->sid);
if (session) {
sess = session_lookup(target, info->sid);
if (sess != NULL) {
PRINT_ERROR("Attempt to add session with existing SID %llx",
info->sid);
err = -EEXIST;
@@ -179,36 +159,63 @@ int session_add(struct iscsi_target *target,
* We need to find the latest session to correctly handle
* multi-reinstatements
*/
list_for_each_entry_reverse(session, &target->session_list,
list_for_each_entry_reverse(sess, &target->session_list,
session_list_entry) {
union iscsi_sid i = *(union iscsi_sid *)&session->sid;
union iscsi_sid i = *(union iscsi_sid *)&sess->sid;
i.id.tsih = 0;
if ((sid.id64 == i.id64) &&
(strcmp(info->initiator_name, session->initiator_name) == 0)) {
if (!session->sess_shutting_down) {
(strcmp(info->initiator_name, sess->initiator_name) == 0)) {
if (!sess->sess_shutting_down) {
/* session reinstatement */
old_sess = session;
old_sess = sess;
}
break;
}
}
sess = NULL;
session = new_sess;
list_add_tail(&session->session_list_entry, &target->session_list);
list_add_tail(&new_sess->session_list_entry, &target->session_list);
if (old_sess != NULL)
session_reinstate(old_sess, session);
if (old_sess != NULL) {
reinstatement = true;
TRACE_MGMT_DBG("Reinstating sess %p with SID %llx (old %p, "
"SID %llx)", new_sess, new_sess->sid, old_sess,
old_sess->sid);
new_sess->sess_reinstating = 1;
old_sess->sess_reinst_successor = new_sess;
target_del_session(old_sess->target, old_sess, 0);
}
out_unlock:
mutex_unlock(&target->target_mutex);
if (reinstatement) {
/*
* Mutex target_mgmt_mutex won't allow to add connections to
* the new session after target_mutex was dropped, so it's safe
* to replace the initial UA without it. We can't do it under
* target_mutex, because otherwise we will establish a
* circular locking dependency between target_mutex and
* scst_mutex in SCST core (iscsi_report_aen() called by
* SCST core under scst_mutex).
*/
scst_set_initial_UA(new_sess->scst_sess,
SCST_LOAD_SENSE(scst_sense_nexus_loss_UA));
}
out:
return err;
out_err_unlock:
new_sess->deleted_from_session_list = 1;
mutex_unlock(&target->target_mutex);
scst_unregister_session(new_sess->scst_sess, 1, NULL);
new_sess->scst_sess = NULL;
new_sess->deleted_from_session_list = 1; /* it wasn't added, actually */
session_free(new_sess);
goto out_unlock;
goto out;
}
/* target_mutex supposed to be locked */