[src/trunk]: src/sys/dev/scsipi Add locking for periph_active and flags. The ...

[mlelstv <mlelstv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/e551c7f38cf3
branches:  trunk
changeset: 819762:e551c7f38cf3
user:      mlelstv <mlelstv%NetBSD.org@localhost>
date:      Fri Dec 16 15:00:52 2016 +0000

description:
Add locking for periph_active and flags. The operations aren't atomic.

diffstat:

 sys/dev/scsipi/scsipi_base.c |  17 +++++++++++++----
 1 files changed, 13 insertions(+), 4 deletions(-)

diffs (69 lines):

diff -r cd686c54b16b -r e551c7f38cf3 sys/dev/scsipi/scsipi_base.c
--- a/sys/dev/scsipi/scsipi_base.c      Fri Dec 16 14:58:53 2016 +0000
+++ b/sys/dev/scsipi/scsipi_base.c      Fri Dec 16 15:00:52 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: scsipi_base.c,v 1.169 2016/11/29 03:23:00 mlelstv Exp $        */
+/*     $NetBSD: scsipi_base.c,v 1.170 2016/12/16 15:00:52 mlelstv Exp $        */
 
 /*-
  * Copyright (c) 1998, 1999, 2000, 2002, 2003, 2004 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: scsipi_base.c,v 1.169 2016/11/29 03:23:00 mlelstv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: scsipi_base.c,v 1.170 2016/12/16 15:00:52 mlelstv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_scsi.h"
@@ -410,6 +410,7 @@
 scsipi_get_xs(struct scsipi_periph *periph, int flags)
 {
        struct scsipi_xfer *xs;
+       bool lock = (flags & XS_CTL_NOSLEEP) == 0;
 
        SC_DEBUG(periph, SCSIPI_DB3, ("scsipi_get_xs\n"));
 
@@ -444,6 +445,8 @@
         *        command, URGENT commands must block, because only
         *        one recovery command can execute at a time.
         */
+       if (lock)
+               mutex_enter(chan_mtx(periph->periph_channel));
        for (;;) {
                if (flags & XS_CTL_URGENT) {
                        if (periph->periph_active > periph->periph_openings)
@@ -467,25 +470,31 @@
 
  wait_for_opening:
                if (flags & XS_CTL_NOSLEEP) {
+                       KASSERT(!lock);
                        return (NULL);
                }
+               KASSERT(lock);
                SC_DEBUG(periph, SCSIPI_DB3, ("sleeping\n"));
-               mutex_enter(chan_mtx(periph->periph_channel));
                periph->periph_flags |= PERIPH_WAITING;
                cv_wait(periph_cv_periph(periph),
                    chan_mtx(periph->periph_channel));
+       }
+       if (lock)
                mutex_exit(chan_mtx(periph->periph_channel));
-       }
 
        SC_DEBUG(periph, SCSIPI_DB3, ("calling pool_get\n"));
        xs = pool_get(&scsipi_xfer_pool,
            ((flags & XS_CTL_NOSLEEP) != 0 ? PR_NOWAIT : PR_WAITOK));
        if (xs == NULL) {
+               if (lock)
+                       mutex_enter(chan_mtx(periph->periph_channel));
                if (flags & XS_CTL_URGENT) {
                        if ((flags & XS_CTL_REQSENSE) == 0)
                                periph->periph_flags &= ~PERIPH_RECOVERY_ACTIVE;
                } else
                        periph->periph_active--;
+               if (lock)
+                       mutex_exit(chan_mtx(periph->periph_channel));
                scsipi_printaddr(periph);
                printf("unable to allocate %sscsipi_xfer\n",
                    (flags & XS_CTL_URGENT) ? "URGENT " : "");