From f2a20b166a1efde194b39d8fae5841b843819f4d Mon Sep 17 00:00:00 2001
From: Alexander Motin <mav@FreeBSD.org>
Date: Wed, 5 Aug 2015 21:58:32 +0000
Subject: [PATCH] Relax serialization of SYNCHRONIZE CACHE commands.

Before this change SYNCHRONIZE CACHE commands were executed exclusively,
as if they had ORDERED tag.  But looking through SCSI specs I've found
no any reason to be so strict.  For reads this ordering seems pointless.
For writes it looks less obvious, so I left ordering against preceeding
write commands, while following ones are no longer required to wait.

MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.
---
 sys/cam/ctl/ctl_cmd_table.c |  8 ++++----
 sys/cam/ctl/ctl_private.h   |  1 +
 sys/cam/ctl/ctl_ser_table.c | 29 +++++++++++++++--------------
 3 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/sys/cam/ctl/ctl_cmd_table.c b/sys/cam/ctl/ctl_cmd_table.c
index b07ea935570..fbf0d126f8b 100644
--- a/sys/cam/ctl/ctl_cmd_table.c
+++ b/sys/cam/ctl/ctl_cmd_table.c
@@ -785,8 +785,8 @@ const struct ctl_cmd_entry ctl_cmd_table[256] =
 {NULL, CTL_SERIDX_INVLD, CTL_CMD_FLAG_NONE, CTL_LUN_PAT_NONE},
 
 /* 35 SYNCHRONIZE CACHE(10) */
-{ctl_sync_cache, CTL_SERIDX_START, CTL_CMD_FLAG_OK_ON_SLUN |
-				   CTL_FLAG_DATA_NONE,
+{ctl_sync_cache, CTL_SERIDX_SYNC, CTL_CMD_FLAG_OK_ON_SLUN |
+				  CTL_FLAG_DATA_NONE,
  CTL_LUN_PAT_NONE,
  10, {0, 0xff, 0xff, 0xff, 0xff, 0, 0xff, 0xff, 0x07}},
 
@@ -1138,8 +1138,8 @@ const struct ctl_cmd_entry ctl_cmd_table[256] =
 {NULL, CTL_SERIDX_INVLD, CTL_CMD_FLAG_NONE, CTL_LUN_PAT_NONE},
 
 /* 91 SYNCHRONIZE CACHE(16) */
-{ctl_sync_cache, CTL_SERIDX_START, CTL_CMD_FLAG_OK_ON_SLUN |
-				   CTL_FLAG_DATA_NONE,
+{ctl_sync_cache, CTL_SERIDX_SYNC, CTL_CMD_FLAG_OK_ON_SLUN |
+				  CTL_FLAG_DATA_NONE,
  CTL_LUN_PAT_NONE,
  16, {0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
       0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0x07}},
diff --git a/sys/cam/ctl/ctl_private.h b/sys/cam/ctl/ctl_private.h
index 8a00b5cae90..a038552e3c4 100644
--- a/sys/cam/ctl/ctl_private.h
+++ b/sys/cam/ctl/ctl_private.h
@@ -141,6 +141,7 @@ typedef enum {
 	CTL_SERIDX_READ,
 	CTL_SERIDX_WRITE,
 	CTL_SERIDX_UNMAP,
+	CTL_SERIDX_SYNC,
 	CTL_SERIDX_MD_SNS,
 	CTL_SERIDX_MD_SEL,
 	CTL_SERIDX_RQ_SNS,
diff --git a/sys/cam/ctl/ctl_ser_table.c b/sys/cam/ctl/ctl_ser_table.c
index ee2d019b528..8d5d6bce81b 100644
--- a/sys/cam/ctl/ctl_ser_table.c
+++ b/sys/cam/ctl/ctl_ser_table.c
@@ -63,19 +63,20 @@
 
 static ctl_serialize_action
 ctl_serialize_table[CTL_SERIDX_COUNT][CTL_SERIDX_COUNT] = {
-/**>IDX_ :: 2nd:TUR RD  WRT UNM MDSN MDSL RQSN INQ RDCP RES LSNS FMT STR*/
-/*TUR     */{   pS, pS, pS, pS, bK,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
-/*READ    */{   pS, xS, xT, bO, bK,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
-/*WRITE   */{   pS, xT, xT, bO, bK,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
-/*UNMAP   */{   pS, xO, xO, pS, bK,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
-/*MD_SNS  */{   bK, bK, bK, bK, pS,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
-/*MD_SEL  */{   bK, bK, bK, bK, bK,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
-/*RQ_SNS  */{   pS, pS, pS, pS, pS,  pS,  bK,  pS, pS,  bK, pS,  bK, bK},
-/*INQ     */{   pS, pS, pS, pS, pS,  pS,  bK,  pS, pS,  pS, pS,  bK, bK},
-/*RD_CAP  */{   pS, pS, pS, pS, pS,  pS,  bK,  pS, pS,  pS, pS,  bK, pS},
-/*RES     */{   bK, bK, bK, bK, bK,  bK,  bK,  pS, bK,  bK, bK,  bK, bK},
-/*LOG_SNS */{   pS, pS, pS, pS, pS,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
-/*FORMAT  */{   pS, bK, bK, bK, bK,  bK,  pS,  pS, bK,  bK, bK,  bK, bK},
-/*START   */{   bK, bK, bK, bK, bK,  bK,  bK,  pS, bK,  bK, bK,  bK, bK},
+/**>IDX_ :: 2nd:TUR RD  WRT UNM SYN MDSN MDSL RQSN INQ RDCP RES LSNS FMT STR*/
+/*TUR     */{   pS, pS, pS, pS, pS, bK,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
+/*READ    */{   pS, xS, xT, bO, pS, bK,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
+/*WRITE   */{   pS, xT, xT, bO, bO, bK,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
+/*UNMAP   */{   pS, xO, xO, pS, pS, bK,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
+/*SYNC    */{   pS, pS, pS, pS, pS, bK,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
+/*MD_SNS  */{   bK, bK, bK, bK, bK, pS,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
+/*MD_SEL  */{   bK, bK, bK, bK, bK, bK,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
+/*RQ_SNS  */{   pS, pS, pS, pS, pS, pS,  pS,  bK,  pS, pS,  bK, pS,  bK, bK},
+/*INQ     */{   pS, pS, pS, pS, pS, pS,  pS,  bK,  pS, pS,  pS, pS,  bK, bK},
+/*RD_CAP  */{   pS, pS, pS, pS, pS, pS,  pS,  bK,  pS, pS,  pS, pS,  bK, pS},
+/*RES     */{   bK, bK, bK, bK, bK, bK,  bK,  bK,  pS, bK,  bK, bK,  bK, bK},
+/*LOG_SNS */{   pS, pS, pS, pS, pS, pS,  bK,  bK,  pS, pS,  bK, pS,  bK, bK},
+/*FORMAT  */{   pS, bK, bK, bK, bK, bK,  bK,  pS,  pS, bK,  bK, bK,  bK, bK},
+/*START   */{   bK, bK, bK, bK, bK, bK,  bK,  bK,  pS, bK,  bK, bK,  bK, bK},
 };