Author: trasz
Date: Thu Mar 15 17:36:13 2018
New Revision: 331013
URL: https://svnweb.freebsd.org/changeset/base/331013
Log:
Fix iSCSI target crash on session reinstation.
The crash scenario goes like this: there's a thread waiting on "reinstate";
because it doesn't update the timeout counter it gets terminated by the
callout; at this point the maintenance thread starts the termination routine.
The first thread finishes waiting, proceeds to icl_conn_handoff(), and drops
the refcount, which allows the maintenance thread to free its resources. At
this point another thread receives a PDU. Boom.
PR: 222898, 219866
Reported by: Eugene M. Zheganin <emz at norma.perm.ru>
Tested by: Eugene M. Zheganin <emz at norma.perm.ru>
Reviewed by: mav@ (earlier version)
MFC after: 2 weeks
Sponsored by: playkey.net
Modified:
head/sys/cam/ctl/ctl_frontend_iscsi.c
head/sys/cam/ctl/ctl_frontend_iscsi.h
Modified: head/sys/cam/ctl/ctl_frontend_iscsi.c
==============================================================================
--- head/sys/cam/ctl/ctl_frontend_iscsi.c Thu Mar 15 17:15:40 2018
(r331012)
+++ head/sys/cam/ctl/ctl_frontend_iscsi.c Thu Mar 15 17:36:13 2018
(r331013)
@@ -1164,11 +1164,11 @@ cfiscsi_maintenance_thread(void *arg)
for (;;) {
CFISCSI_SESSION_LOCK(cs);
- if (cs->cs_terminating == false)
+ if (cs->cs_terminating == false || cs->cs_handoff_in_progress)
cv_wait(&cs->cs_maintenance_cv, &cs->cs_lock);
CFISCSI_SESSION_UNLOCK(cs);
- if (cs->cs_terminating) {
+ if (cs->cs_terminating && cs->cs_handoff_in_progress == false) {
/*
* We used to wait up to 30 seconds to deliver queued
@@ -1196,8 +1196,6 @@ static void
cfiscsi_session_terminate(struct cfiscsi_session *cs)
{
- if (cs->cs_terminating)
- return;
cs->cs_terminating = true;
cv_signal(&cs->cs_maintenance_cv);
#ifdef ICL_KERNEL_PROXY
@@ -1268,6 +1266,13 @@ cfiscsi_session_new(struct cfiscsi_softc *softc, const
cv_init(&cs->cs_login_cv, "cfiscsi_login");
#endif
+ /*
+ * The purpose of this is to avoid racing with session shutdown.
+ * Otherwise we could have the maintenance thread call icl_conn_close()
+ * before we call icl_conn_handoff().
+ */
+ cs->cs_handoff_in_progress = true;
+
cs->cs_conn = icl_new_conn(offload, false, "cfiscsi", &cs->cs_lock);
if (cs->cs_conn == NULL) {
free(cs, M_CFISCSI);
@@ -1378,8 +1383,18 @@ cfiscsi_accept(struct socket *so, struct sockaddr *sa,
icl_conn_handoff_sock(cs->cs_conn, so);
cs->cs_initiator_sa = sa;
cs->cs_portal_id = portal_id;
+ cs->cs_handoff_in_progress = false;
cs->cs_waiting_for_ctld = true;
cv_signal(&cfiscsi_softc.accept_cv);
+
+ CFISCSI_SESSION_LOCK(cs);
+ /*
+ * Wake up the maintenance thread if we got scheduled for termination
+ * somewhere between cfiscsi_session_new() and icl_conn_handoff_sock().
+ */
+ if (cs->cs_terminating)
+ cfiscsi_session_terminate(cs);
+ CFISCSI_SESSION_UNLOCK(cs);
}
#endif
@@ -1559,6 +1574,7 @@ cfiscsi_ioctl_handoff(struct ctl_iscsi *ci)
mtx_lock(&softc->lock);
if (ct->ct_online == 0) {
mtx_unlock(&softc->lock);
+ cs->cs_handoff_in_progress = false;
cfiscsi_session_terminate(cs);
cfiscsi_target_release(ct);
ci->status = CTL_ISCSI_ERROR;
@@ -1569,7 +1585,6 @@ cfiscsi_ioctl_handoff(struct ctl_iscsi *ci)
cs->cs_target = ct;
mtx_unlock(&softc->lock);
- refcount_acquire(&cs->cs_outstanding_ctl_pdus);
restart:
if (!cs->cs_terminating) {
mtx_lock(&softc->lock);
@@ -1606,8 +1621,8 @@ restart:
#endif
error = icl_conn_handoff(cs->cs_conn, cihp->socket);
if (error != 0) {
+ cs->cs_handoff_in_progress = false;
cfiscsi_session_terminate(cs);
- refcount_release(&cs->cs_outstanding_ctl_pdus);
ci->status = CTL_ISCSI_ERROR;
snprintf(ci->error_str, sizeof(ci->error_str),
"%s: icl_conn_handoff failed with error %d",
@@ -1632,7 +1647,16 @@ restart:
}
#endif
- refcount_release(&cs->cs_outstanding_ctl_pdus);
+ CFISCSI_SESSION_LOCK(cs);
+ cs->cs_handoff_in_progress = false;
+
+ /*
+ * Wake up the maintenance thread if we got scheduled for termination.
+ */
+ if (cs->cs_terminating)
+ cfiscsi_session_terminate(cs);
+ CFISCSI_SESSION_UNLOCK(cs);
+
ci->status = CTL_ISCSI_OK;
}
Modified: head/sys/cam/ctl/ctl_frontend_iscsi.h
==============================================================================
--- head/sys/cam/ctl/ctl_frontend_iscsi.h Thu Mar 15 17:15:40 2018
(r331012)
+++ head/sys/cam/ctl/ctl_frontend_iscsi.h Thu Mar 15 17:36:13 2018
(r331013)
@@ -85,6 +85,7 @@ struct cfiscsi_session {
int cs_timeout;
struct cv cs_maintenance_cv;
bool cs_terminating;
+ bool cs_handoff_in_progress;
bool cs_tasks_aborted;
int cs_max_recv_data_segment_length;
int cs_max_send_data_segment_length;
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