A test program's runtime became impractically long since any non
zero ndelay (e.g. 1 nanosec) caused Start Stop Unit to delay
over 8 magnitudes greater than other commands. This patch skips
long delays (on Start Stop Unit and Synchronize Cache) if ndelay
is less than or equal to 10 microsecs.

Signed-off-by: Douglas Gilbert <dgilb...@interlog.com>
---
This patch is against MKP's 4.19/scsi-queue branch.

Re-arrange if condition so least likely is first part of && .

 drivers/scsi/scsi_debug.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 24d7496cd9e2..4dda192b8fba 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -5790,11 +5790,13 @@ static int scsi_debug_queuecommand(struct Scsi_Host 
*shost,
 fini:
        if (F_DELAY_OVERR & flags)
                return schedule_resp(scp, devip, errsts, pfp, 0, 0);
-       else if ((sdebug_jdelay || sdebug_ndelay) && (flags & F_LONG_DELAY)) {
+       else if ((flags & F_LONG_DELAY) && (sdebug_jdelay > 0 ||
+                                           sdebug_ndelay > 10000)) {
                /*
-                * If any delay is active, for F_SSU_DELAY want at least 1
-                * second and if sdebug_jdelay>0 want a long delay of that
-                * many seconds; for F_SYNC_DELAY want 1/20 of that.
+                * Skip long delays if ndelay <= 10 microseconds. Otherwise
+                * for Start Stop Unit (SSU) want at least 1 second delay and
+                * if sdebug_jdelay>1 want a long delay of that many seconds.
+                * For Synchronize Cache want 1/20 of SSU's delay.
                 */
                int jdelay = (sdebug_jdelay < 2) ? 1 : sdebug_jdelay;
                int denom = (flags & F_SYNC_DELAY) ? 20 : 1;
-- 
2.17.1

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