s390/qdio: add sanity checks to the fast-requeue path (a6ec414a) · Commits · e / devices / android_kernel_fairphone_FP5

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>

drivers/s390/cio/qdio_main.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -1558,13 +1558,13 @@ 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);
		}

		/* in case of SIGA errors we must process the error immediately */