[S390] qdio: improve inbound buffer acknowledgement
- Use automatic acknowledgement of incoming buffers in QEBSM mode
- Move ACK for non-QEBSM mode always to the newest buffer to prevent
a race with qdio_stop_polling
- Remove the polling spinlock, the upper layer drivers return new buffers
in the same code path and could not run in parallel
- Don't flood the error log in case of no-target-buffer-empty
- In handle_inbound we check if we would overwrite an ACK'ed buffer, if so
advance the pointer to the oldest ACK'ed buffer so we don't overwrite an
empty buffer in qdio_stop_polling
Signed-off-by: Jan Glauber <jang@linux.vnet.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 c810214..0b4c09c 100644
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -112,12 +112,13 @@
* @state: state of the extracted buffers
* @start: buffer number to start at
* @count: count of buffers to examine
+ * @auto_ack: automatically acknowledge buffers
*
* Returns the number of successfull extracted equal buffer states.
* Stops processing if a state is different from the last buffers state.
*/
static int qdio_do_eqbs(struct qdio_q *q, unsigned char *state,
- int start, int count)
+ int start, int count, int auto_ack)
{
unsigned int ccq = 0;
int tmp_count = count, tmp_start = start;
@@ -130,7 +131,8 @@
if (!q->is_input_q)
nr += q->irq_ptr->nr_input_qs;
again:
- ccq = do_eqbs(q->irq_ptr->sch_token, state, nr, &tmp_start, &tmp_count);
+ ccq = do_eqbs(q->irq_ptr->sch_token, state, nr, &tmp_start, &tmp_count,
+ auto_ack);
rc = qdio_check_ccq(q, ccq);
/* At least one buffer was processed, return and extract the remaining
@@ -176,6 +178,9 @@
int nr = q->nr;
int rc;
+ if (!count)
+ return 0;
+
BUG_ON(!q->irq_ptr->sch_token);
qdio_perf_stat_inc(&perf_stats.debug_sqbs_all);
@@ -203,7 +208,8 @@
/* returns number of examined buffers and their common state in *state */
static inline int get_buf_states(struct qdio_q *q, unsigned int bufnr,
- unsigned char *state, unsigned int count)
+ unsigned char *state, unsigned int count,
+ int auto_ack)
{
unsigned char __state = 0;
int i;
@@ -212,7 +218,7 @@
BUG_ON(count > QDIO_MAX_BUFFERS_PER_Q);
if (is_qebsm(q))
- return qdio_do_eqbs(q, state, bufnr, count);
+ return qdio_do_eqbs(q, state, bufnr, count, auto_ack);
for (i = 0; i < count; i++) {
if (!__state)
@@ -226,9 +232,9 @@
}
inline int get_buf_state(struct qdio_q *q, unsigned int bufnr,
- unsigned char *state)
+ unsigned char *state, int auto_ack)
{
- return get_buf_states(q, bufnr, state, 1);
+ return get_buf_states(q, bufnr, state, 1, auto_ack);
}
/* wrap-around safe setting of slsb states, returns number of changed buffers */
@@ -376,29 +382,91 @@
inline void qdio_stop_polling(struct qdio_q *q)
{
- spin_lock_bh(&q->u.in.lock);
- if (!q->u.in.polling) {
- spin_unlock_bh(&q->u.in.lock);
+ if (!q->u.in.polling)
return;
- }
+
q->u.in.polling = 0;
qdio_perf_stat_inc(&perf_stats.debug_stop_polling);
/* show the card that we are not polling anymore */
- set_buf_state(q, q->last_move_ftc, SLSB_P_INPUT_NOT_INIT);
- spin_unlock_bh(&q->u.in.lock);
+ if (is_qebsm(q)) {
+ set_buf_states(q, q->last_move_ftc, SLSB_P_INPUT_NOT_INIT,
+ q->u.in.ack_count);
+ q->u.in.ack_count = 0;
+ } else
+ set_buf_state(q, q->last_move_ftc, SLSB_P_INPUT_NOT_INIT);
}
-static void announce_buffer_error(struct qdio_q *q)
+static void announce_buffer_error(struct qdio_q *q, int count)
{
+ q->qdio_error = QDIO_ERROR_SLSB_STATE;
+
+ /* special handling for no target buffer empty */
+ if ((!q->is_input_q &&
+ (q->sbal[q->first_to_check]->element[15].flags & 0xff) == 0x10)) {
+ qdio_perf_stat_inc(&perf_stats.outbound_target_full);
+ DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "OUTFULL FTC:%3d",
+ q->first_to_check);
+ return;
+ }
+
DBF_ERROR("%4x BUF ERROR", SCH_NO(q));
DBF_ERROR((q->is_input_q) ? "IN:%2d" : "OUT:%2d", q->nr);
- DBF_ERROR("FTC:%3d", q->first_to_check);
+ DBF_ERROR("FTC:%3d C:%3d", q->first_to_check, count);
DBF_ERROR("F14:%2x F15:%2x",
q->sbal[q->first_to_check]->element[14].flags & 0xff,
q->sbal[q->first_to_check]->element[15].flags & 0xff);
+}
- q->qdio_error = QDIO_ERROR_SLSB_STATE;
+static inline void inbound_primed(struct qdio_q *q, int count)
+{
+ int new;
+
+ DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "in prim: %3d", count);
+
+ /* for QEBSM the ACK was already set by EQBS */
+ if (is_qebsm(q)) {
+ if (!q->u.in.polling) {
+ q->u.in.polling = 1;
+ q->u.in.ack_count = count;
+ q->last_move_ftc = q->first_to_check;
+ return;
+ }
+
+ /* delete the previous ACK's */
+ set_buf_states(q, q->last_move_ftc, SLSB_P_INPUT_NOT_INIT,
+ q->u.in.ack_count);
+ q->u.in.ack_count = count;
+ q->last_move_ftc = q->first_to_check;
+ return;
+ }
+
+ /*
+ * ACK the newest buffer. The ACK will be removed in qdio_stop_polling
+ * or by the next inbound run.
+ */
+ new = add_buf(q->first_to_check, count - 1);
+ if (q->u.in.polling) {
+ /* reset the previous ACK but first set the new one */
+ set_buf_state(q, new, SLSB_P_INPUT_ACK);
+ set_buf_state(q, q->last_move_ftc, SLSB_P_INPUT_NOT_INIT);
+ }
+ else {
+ q->u.in.polling = 1;
+ set_buf_state(q, q->first_to_check, SLSB_P_INPUT_ACK);
+ }
+
+ q->last_move_ftc = new;
+ count--;
+ if (!count)
+ return;
+
+ /*
+ * Need to change all PRIMED buffers to NOT_INIT, otherwise
+ * we're loosing initiative in the thinint code.
+ */
+ set_buf_states(q, next_buf(q->first_to_check), SLSB_P_INPUT_NOT_INIT,
+ count);
}
static int get_inbound_buffer_frontier(struct qdio_q *q)
@@ -407,13 +475,6 @@
unsigned char state;
/*
- * If we still poll don't update last_move_ftc, keep the
- * previously ACK buffer there.
- */
- if (!q->u.in.polling)
- q->last_move_ftc = q->first_to_check;
-
- /*
* Don't check 128 buffers, as otherwise qdio_inbound_q_moved
* would return 0.
*/
@@ -433,34 +494,13 @@
if (q->first_to_check == stop)
goto out;
- count = get_buf_states(q, q->first_to_check, &state, count);
+ count = get_buf_states(q, q->first_to_check, &state, count, 1);
if (!count)
goto out;
switch (state) {
case SLSB_P_INPUT_PRIMED:
- DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "in prim: %3d", count);
-
- /*
- * Only ACK the first buffer. The ACK will be removed in
- * qdio_stop_polling.
- */
- if (q->u.in.polling)
- state = SLSB_P_INPUT_NOT_INIT;
- else {
- q->u.in.polling = 1;
- state = SLSB_P_INPUT_ACK;
- }
- set_buf_state(q, q->first_to_check, state);
-
- /*
- * Need to change all PRIMED buffers to NOT_INIT, otherwise
- * we're loosing initiative in the thinint code.
- */
- if (count > 1)
- set_buf_states(q, next_buf(q->first_to_check),
- SLSB_P_INPUT_NOT_INIT, count - 1);
-
+ inbound_primed(q, count);
/*
* No siga-sync needed for non-qebsm here, as the inbound queue
* will be synced on the next siga-r, resp.
@@ -470,7 +510,7 @@
atomic_sub(count, &q->nr_buf_used);
goto check_next;
case SLSB_P_INPUT_ERROR:
- announce_buffer_error(q);
+ announce_buffer_error(q, count);
/* process the buffer, the upper layer will take care of it */
q->first_to_check = add_buf(q->first_to_check, count);
atomic_sub(count, &q->nr_buf_used);
@@ -516,7 +556,7 @@
*/
qdio_siga_sync_q(q);
- get_buf_state(q, q->first_to_check, &state);
+ get_buf_state(q, q->first_to_check, &state, 0);
if (state == SLSB_P_INPUT_PRIMED)
/* we got something to do */
return 0;
@@ -619,7 +659,7 @@
if (q->first_to_check == stop)
return q->first_to_check;
- count = get_buf_states(q, q->first_to_check, &state, count);
+ count = get_buf_states(q, q->first_to_check, &state, count, 0);
if (!count)
return q->first_to_check;
@@ -638,7 +678,7 @@
break;
goto check_next;
case SLSB_P_OUTPUT_ERROR:
- announce_buffer_error(q);
+ announce_buffer_error(q, count);
/* process the buffer, the upper layer will take care of it */
q->first_to_check = add_buf(q->first_to_check, count);
atomic_sub(count, &q->nr_buf_used);
@@ -1451,23 +1491,38 @@
static void handle_inbound(struct qdio_q *q, unsigned int callflags,
int bufnr, int count)
{
- unsigned long flags;
- int used, rc;
+ int used, rc, diff;
- /*
- * do_QDIO could run in parallel with the queue tasklet so the
- * upper-layer programm could empty the ACK'ed buffer here.
- * If that happens we must clear the polling flag, otherwise
- * qdio_stop_polling() could set the buffer to NOT_INIT after
- * it was set to EMPTY which would kill us.
- */
- spin_lock_irqsave(&q->u.in.lock, flags);
- if (q->u.in.polling)
- if (buf_in_between(q->last_move_ftc, bufnr, count))
+ if (!q->u.in.polling)
+ goto set;
+
+ /* protect against stop polling setting an ACK for an emptied slsb */
+ if (count == QDIO_MAX_BUFFERS_PER_Q) {
+ /* overwriting everything, just delete polling status */
+ q->u.in.polling = 0;
+ q->u.in.ack_count = 0;
+ goto set;
+ } else if (buf_in_between(q->last_move_ftc, bufnr, count)) {
+ if (is_qebsm(q)) {
+ /* partial overwrite, just update last_move_ftc */
+ diff = add_buf(bufnr, count);
+ diff = sub_buf(diff, q->last_move_ftc);
+ q->u.in.ack_count -= diff;
+ if (q->u.in.ack_count <= 0) {
+ q->u.in.polling = 0;
+ q->u.in.ack_count = 0;
+ /* TODO: must we set last_move_ftc to something meaningful? */
+ goto set;
+ }
+ q->last_move_ftc = add_buf(q->last_move_ftc, diff);
+ }
+ else
+ /* the only ACK will be deleted, so stop polling */
q->u.in.polling = 0;
+ }
+set:
count = set_buf_states(q, bufnr, SLSB_CU_INPUT_EMPTY, count);
- spin_unlock_irqrestore(&q->u.in.lock, flags);
used = atomic_add_return(count, &q->nr_buf_used) - count;
BUG_ON(used + count > QDIO_MAX_BUFFERS_PER_Q);
@@ -1535,7 +1590,7 @@
}
/* try to fast requeue buffers */
- get_buf_state(q, prev_buf(bufnr), &state);
+ get_buf_state(q, prev_buf(bufnr), &state, 0);
if (state != SLSB_CU_OUTPUT_PRIMED)
qdio_kick_outbound_q(q);
else {