From: Julian Wiedmann jwi@linux.ibm.com
[ Upstream commit a6ec414a4dd529eeac5c3ea51c661daba3397108 ]
If the device driver were to send out a full queue's worth of SBALs, current code would end up discovering the last of those SBALs as PRIMED and erroneously skip the SIGA-w. This immediately stalls the queue.
Add a check to not attempt fast-requeue in this case. While at it also make sure that the state of the previous SBAL was successfully extracted before inspecting it.
Signed-off-by: Julian Wiedmann jwi@linux.ibm.com Reviewed-by: Jens Remus jremus@linux.ibm.com Signed-off-by: Heiko Carstens heiko.carstens@de.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/s390/cio/qdio_main.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c index ab8dd81fbc2b1..1a40c73961b83 100644 --- a/drivers/s390/cio/qdio_main.c +++ b/drivers/s390/cio/qdio_main.c @@ -1577,13 +1577,13 @@ static int handle_outbound(struct qdio_q *q, unsigned int callflags, rc = qdio_kick_outbound_q(q, phys_aob); } else if (need_siga_sync(q)) { rc = qdio_siga_sync_q(q); + } else if (count < QDIO_MAX_BUFFERS_PER_Q && + get_buf_state(q, prev_buf(bufnr), &state, 0) > 0 && + state == SLSB_CU_OUTPUT_PRIMED) { + /* The previous buffer is not processed yet, tack on. */ + qperf_inc(q, fast_requeue); } else { - /* try to fast requeue buffers */ - get_buf_state(q, prev_buf(bufnr), &state, 0); - if (state != SLSB_CU_OUTPUT_PRIMED) - rc = qdio_kick_outbound_q(q, 0); - else - qperf_inc(q, fast_requeue); + rc = qdio_kick_outbound_q(q, 0); }
/* in case of SIGA errors we must process the error immediately */