s390/qdio: consolidate index tracking for queue scan

qdio.ko offers a small number of high-level functions to drive the
scanning of a QDIO queue for ready-to-process SBALs:
qdio_get_next_buffers(), __[ti]qdio_inbound_processing() and
__qdio_outbound_processing().

Let each of those functions maintain the 'start' index for their current
scan, and pass it to lower-level helpers as needed. This improves the
code's overall layering, and allows us to eliminate the additional
first_to_kick cursor with a follow-on patch.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index 045f2aad0b3cf9a3573958d49087181a2c5840e2..cfce255521ac4b2a8d1e2ab0ffba19d597810ca7 100644 (file)
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -492,9 +492,8 @@ static inline void inbound_primed(struct qdio_q *q, unsigned int start,
        set_buf_states(q, start, SLSB_P_INPUT_NOT_INIT, count);
 }
 
-static int get_inbound_buffer_frontier(struct qdio_q *q)
+static int get_inbound_buffer_frontier(struct qdio_q *q, unsigned int start)
 {
-       unsigned int start = q->first_to_check;
        unsigned char state = 0;
        int count;
 
@@ -519,7 +518,6 @@ static int get_inbound_buffer_frontier(struct qdio_q *q)
        switch (state) {
        case SLSB_P_INPUT_PRIMED:
                inbound_primed(q, start, count);
-               q->first_to_check = add_buf(start, count);
                if (atomic_sub_return(count, &q->nr_buf_used) == 0)
                        qperf_inc(q, inbound_queue_full);
                if (q->irq_ptr->perf_stat_enabled)
@@ -527,7 +525,6 @@ static int get_inbound_buffer_frontier(struct qdio_q *q)
                return count;
        case SLSB_P_INPUT_ERROR:
                process_buffer_error(q, start, count);
-               q->first_to_check = add_buf(start, count);
                if (atomic_sub_return(count, &q->nr_buf_used) == 0)
                        qperf_inc(q, inbound_queue_full);
                if (q->irq_ptr->perf_stat_enabled)
@@ -547,11 +544,11 @@ static int get_inbound_buffer_frontier(struct qdio_q *q)
        }
 }
 
-static int qdio_inbound_q_moved(struct qdio_q *q)
+static int qdio_inbound_q_moved(struct qdio_q *q, unsigned int start)
 {
        int count;
 
-       count = get_inbound_buffer_frontier(q);
+       count = get_inbound_buffer_frontier(q, start);
 
        if (count && !is_thinint_irq(q->irq_ptr) && MACHINE_IS_LPAR)
                q->u.in.timestamp = get_tod_clock();
@@ -559,9 +556,8 @@ static int qdio_inbound_q_moved(struct qdio_q *q)
        return count;
 }
 
-static inline int qdio_inbound_q_done(struct qdio_q *q)
+static inline int qdio_inbound_q_done(struct qdio_q *q, unsigned int start)
 {
-       unsigned int start = q->first_to_check;
        unsigned char state = 0;
 
        if (!atomic_read(&q->nr_buf_used))
@@ -672,17 +668,20 @@ static inline int qdio_tasklet_schedule(struct qdio_q *q)
 
 static void __qdio_inbound_processing(struct qdio_q *q)
 {
+       unsigned int start = q->first_to_check;
        int count;
 
        qperf_inc(q, tasklet_inbound);
 
-       count = qdio_inbound_q_moved(q);
+       count = qdio_inbound_q_moved(q, start);
        if (count == 0)
                return;
 
+       start = add_buf(start, count);
+       q->first_to_check = start;
        qdio_kick_handler(q, count);
 
-       if (!qdio_inbound_q_done(q)) {
+       if (!qdio_inbound_q_done(q, start)) {
                /* means poll time is not yet over */
                qperf_inc(q, tasklet_inbound_resched);
                if (!qdio_tasklet_schedule(q))
@@ -694,7 +693,7 @@ static void __qdio_inbound_processing(struct qdio_q *q)
         * We need to check again to not lose initiative after
         * resetting the ACK state.
         */
-       if (!qdio_inbound_q_done(q)) {
+       if (!qdio_inbound_q_done(q, start)) {
                qperf_inc(q, tasklet_inbound_resched2);
                qdio_tasklet_schedule(q);
        }
@@ -706,9 +705,8 @@ void qdio_inbound_processing(unsigned long data)
        __qdio_inbound_processing(q);
 }
 
-static int get_outbound_buffer_frontier(struct qdio_q *q)
+static int get_outbound_buffer_frontier(struct qdio_q *q, unsigned int start)
 {
-       unsigned int start = q->first_to_check;
        unsigned char state = 0;
        int count;
 
@@ -740,13 +738,11 @@ static int get_outbound_buffer_frontier(struct qdio_q *q)
                        "out empty:%1d %02x", q->nr, count);
 
                atomic_sub(count, &q->nr_buf_used);
-               q->first_to_check = add_buf(start, count);
                if (q->irq_ptr->perf_stat_enabled)
                        account_sbals(q, count);
                return count;
        case SLSB_P_OUTPUT_ERROR:
                process_buffer_error(q, start, count);
-               q->first_to_check = add_buf(start, count);
                atomic_sub(count, &q->nr_buf_used);
                if (q->irq_ptr->perf_stat_enabled)
                        account_sbals_error(q, count);
@@ -773,11 +769,11 @@ static inline int qdio_outbound_q_done(struct qdio_q *q)
        return atomic_read(&q->nr_buf_used) == 0;
 }
 
-static inline int qdio_outbound_q_moved(struct qdio_q *q)
+static inline int qdio_outbound_q_moved(struct qdio_q *q, unsigned int start)
 {
        int count;
 
-       count = get_outbound_buffer_frontier(q);
+       count = get_outbound_buffer_frontier(q, start);
 
        if (count)
                DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "out moved:%1d", q->nr);
@@ -829,14 +825,17 @@ retry:
 
 static void __qdio_outbound_processing(struct qdio_q *q)
 {
+       unsigned int start = q->first_to_check;
        int count;
 
        qperf_inc(q, tasklet_outbound);
        WARN_ON_ONCE(atomic_read(&q->nr_buf_used) < 0);
 
-       count = qdio_outbound_q_moved(q);
-       if (count)
+       count = qdio_outbound_q_moved(q, start);
+       if (count) {
+               q->first_to_check = add_buf(start, count);
                qdio_kick_handler(q, count);
+       }
 
        if (queue_type(q) == QDIO_ZFCP_QFMT && !pci_out_supported(q->irq_ptr) &&
            !qdio_outbound_q_done(q))
@@ -891,6 +890,7 @@ static inline void qdio_check_outbound_pci_queues(struct qdio_irq *irq)
 
 static void __tiqdio_inbound_processing(struct qdio_q *q)
 {
+       unsigned int start = q->first_to_check;
        int count;
 
        qperf_inc(q, tasklet_inbound);
@@ -900,13 +900,15 @@ static void __tiqdio_inbound_processing(struct qdio_q *q)
        /* The interrupt could be caused by a PCI request: */
        qdio_check_outbound_pci_queues(q->irq_ptr);
 
-       count = qdio_inbound_q_moved(q);
+       count = qdio_inbound_q_moved(q, start);
        if (count == 0)
                return;
 
+       start = add_buf(start, count);
+       q->first_to_check = start;
        qdio_kick_handler(q, count);
 
-       if (!qdio_inbound_q_done(q)) {
+       if (!qdio_inbound_q_done(q, start)) {
                qperf_inc(q, tasklet_inbound_resched);
                if (!qdio_tasklet_schedule(q))
                        return;
@@ -917,7 +919,7 @@ static void __tiqdio_inbound_processing(struct qdio_q *q)
         * We need to check again to not lose initiative after
         * resetting the ACK state.
         */
-       if (!qdio_inbound_q_done(q)) {
+       if (!qdio_inbound_q_done(q, start)) {
                qperf_inc(q, tasklet_inbound_resched2);
                qdio_tasklet_schedule(q);
        }
@@ -1637,7 +1639,7 @@ int qdio_start_irq(struct ccw_device *cdev, int nr)
         */
        if (test_nonshared_ind(irq_ptr))
                goto rescan;
-       if (!qdio_inbound_q_done(q))
+       if (!qdio_inbound_q_done(q, q->first_to_check))
                goto rescan;
        return 0;
 
@@ -1668,11 +1670,13 @@ int qdio_get_next_buffers(struct ccw_device *cdev, int nr, int *bufnr,
 {
        struct qdio_q *q;
        struct qdio_irq *irq_ptr = cdev->private->qdio_data;
+       unsigned int start;
        int count;
 
        if (!irq_ptr)
                return -ENODEV;
        q = irq_ptr->input_qs[nr];
+       start = q->first_to_check;
 
        /*
         * Cannot rely on automatic sync after interrupt since queues may
@@ -1683,10 +1687,13 @@ int qdio_get_next_buffers(struct ccw_device *cdev, int nr, int *bufnr,
 
        qdio_check_outbound_pci_queues(irq_ptr);
 
-       count = qdio_inbound_q_moved(q);
+       count = qdio_inbound_q_moved(q, start);
        if (count == 0)
                return 0;
 
+       start = add_buf(start, count);
+       q->first_to_check = start;
+
        /* Note: upper-layer MUST stop processing immediately here ... */
        if (unlikely(q->irq_ptr->state != QDIO_IRQ_STATE_ACTIVE))
                return -EIO;