s390/qdio: handle PENDING state for QEBSM devices

BugLink: https://bugs.launchpad.net/bugs/1840081

[ Upstream commit 04310324 ]

When a CQ-enabled device uses QEBSM for SBAL state inspection,
get_buf_states() can return the PENDING state for an Output Queue.
get_outbound_buffer_frontier() isn't prepared for this, and any PENDING
buffer will permanently stall all further completion processing on this
Queue.

This isn't a concern for non-QEBSM devices, as get_buf_states() for such
devices will manually turn PENDING buffers into EMPTY ones.

Fixes: 104ea556 ("qdio: support asynchronous delivery of storage blocks")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/s390/cio/qdio_main.c

@@ -752,6 +752,7 @@ static int get_outbound_buffer_frontier(struct qdio_q *q)
 
 	switch (state) {
 	case SLSB_P_OUTPUT_EMPTY:
+	case SLSB_P_OUTPUT_PENDING:
 		/* the adapter got it */
 		DBF_DEV_EVENT(DBF_INFO, q->irq_ptr,
 			"out empty:%1d %02x", q->nr, count);