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Fix iSCSI target crash on session reinstation.

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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
This commit is contained in:
Edward Tomasz Napierala 2018-03-15 17:36:13 +00:00
parent 94598ac9f9
commit 6616539dcc
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=331013
2 changed files with 32 additions and 7 deletions
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38
sys/cam/ctl/ctl_frontend_iscsi.c
View file

@ -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 char *offload)
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, int portal_id)
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 @@ cfiscsi_ioctl_handoff(struct ctl_iscsi *ci)
#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 @@ cfiscsi_ioctl_handoff(struct ctl_iscsi *ci)
}
#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;
}

1
sys/cam/ctl/ctl_frontend_iscsi.h
View file

@ -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;