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PDU queue out PDUs in order of itt.

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This patch fixes a deadlock case where all available
cmdsns have been used for command PDUs which need
additional Data-OUT PDUs to succeed (e.g. a write16
which is larger than first_burst_len).
In this case the target will never increase the maxcmdsn
leading to a deadlock in iscsi_write_to_socket().
If we receive the R2T for such a write request we will
queue the Data-OUT PDUs but at the end of queue. As
a result they will never be sent as the outqueue is already
stuck.

We fix this by sorting the outqueue by ascending itt.

Signed-off-by: Peter Lieven <pl@kamp.de>
This commit is contained in:
Peter Lieven
2012-11-28 14:04:14 +01:00
parent 722eb013c8
commit 1f4a66abc8
1 changed files with 31 additions and 2 deletions
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33
lib/socket.c
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@@ -51,8 +51,37 @@ static uint32_t iface_rr = 0;
void
iscsi_add_to_outqueue(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
{
SLIST_ADD_END(&iscsi->outqueue, pdu);
return;
if (iscsi->outqueue == NULL) {
iscsi->outqueue = pdu;
pdu->next = NULL;
return;
}
struct iscsi_pdu *current = iscsi->outqueue;
struct iscsi_pdu *last = NULL;
/* queue pdus in ascending order of itt.
* ensure that pakets with the same itt are kept in order.
* queue pdus with itt = 0xffffffff (SNACK / DataACK) in order but at head of queue.
*/
do {
if (current->written == 0 && (iscsi_serial32_compare(pdu->itt, current->itt) < 0
|| (pdu->itt == 0xffffffff && current->itt != 0xffffffff))) {
/* insert PDU before the current */
if (last != NULL) {
last->next=pdu;
} else {
iscsi->outqueue=pdu;
}
pdu->next = current;
return;
}
last=current;
current=current->next;
} while (current != NULL);
last->next = pdu;
pdu->next = NULL;
}
void iscsi_decrement_iface_rr() {