[PATCH 8/9] scsi: scsi_debug: Use scsi_host_busy() in delay_store() and ndelay_store()

[John Garry <john.g.garry@oracle.com>]

The functions to update ndelay and delay value first check whether we have
any in-flight IO for any host. It does this by checking if any tag is used
in the global submit queues.

We can achieve the same by setting the host as blocked and then ensuring
that we have no in-flight commands with scsi_host_busy().

Note that scsi_host_busy() checks SCMD_STATE_INFLIGHT flag, which is only
set per command after we ensure that the host is not blocked, i.e. we
will not see more commands active after the check for scsi_host_busy()
returns 0.

Signed-off-by: John Garry <john.g.garry@oracle.com>
---
 drivers/scsi/scsi_debug.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index cc2da4cc62b5..7ef195072d97 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -6059,16 +6059,15 @@ static ssize_t delay_store(struct device_driver *ddp, const char *buf,
 	if (count > 0 && sscanf(buf, "%d", &jdelay) == 1) {
 		res = count;
 		if (sdebug_jdelay != jdelay) {
-			int j, k;
-			struct sdebug_queue *sqp;
+			struct sdebug_host_info *sdhp;
 
 			mutex_lock(&sdebug_host_list_mutex);
 			block_unblock_all_queues(true);
-			for (j = 0, sqp = sdebug_q_arr; j < submit_queues;
-			     ++j, ++sqp) {
-				k = find_first_bit(sqp->in_use_bm,
-						   sdebug_max_queue);
-				if (k != sdebug_max_queue) {
+
+			list_for_each_entry(sdhp, &sdebug_host_list, host_list) {
+				struct Scsi_Host *shost = sdhp->shost;
+
+				if (scsi_host_busy(shost)) {
 					res = -EBUSY;   /* queued commands */
 					break;
 				}
@@ -6101,20 +6100,20 @@ static ssize_t ndelay_store(struct device_driver *ddp, const char *buf,
 	    (ndelay >= 0) && (ndelay < (1000 * 1000 * 1000))) {
 		res = count;
 		if (sdebug_ndelay != ndelay) {
-			int j, k;
-			struct sdebug_queue *sqp;
+			struct sdebug_host_info *sdhp;
 
 			mutex_lock(&sdebug_host_list_mutex);
 			block_unblock_all_queues(true);
-			for (j = 0, sqp = sdebug_q_arr; j < submit_queues;
-			     ++j, ++sqp) {
-				k = find_first_bit(sqp->in_use_bm,
-						   sdebug_max_queue);
-				if (k != sdebug_max_queue) {
+
+			list_for_each_entry(sdhp, &sdebug_host_list, host_list) {
+				struct Scsi_Host *shost = sdhp->shost;
+
+				if (scsi_host_busy(shost)) {
 					res = -EBUSY;   /* queued commands */
 					break;
 				}
 			}
+
 			if (res > 0) {
 				sdebug_ndelay = ndelay;
 				sdebug_jdelay = ndelay  ? JDELAY_OVERRIDDEN
-- 
2.35.3