[src/trunk]: src Try to make sure that the appropriate calls to mutex_enter()...

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

details:   https://anonhg.NetBSD.org/src/rev/67d68beda2d3
branches:  trunk
changeset: 786358:67d68beda2d3
user:      pooka <pooka%NetBSD.org@localhost>
date:      Sat Apr 27 13:59:46 2013 +0000

description:
Try to make sure that the appropriate calls to mutex_enter() takes
a spin mutex (i.e. does not relinquish cpu context while trying to
take the mutex).

Bump the hypercall interface version number.  I'll be doing a bunch
of other cleanups to simplify the interface for the benefit of
alternative hypervisor implementations.  I'll be riding this bump
and doing a second one only after I'm finished with all of the
changes.

diffstat:

 lib/librumpuser/rumpuser_pth.c       |  26 +++++++++++++++++---------
 lib/librumpuser/rumpuser_pth_dummy.c |   6 +++---
 sys/rump/include/rump/rumpuser.h     |   6 +++---
 sys/rump/librump/rumpkern/locks.c    |  35 +++++++++++++++++++++++++++++++----
 sys/rump/librump/rumpkern/locks_up.c |  11 +++++++++--
 5 files changed, 63 insertions(+), 21 deletions(-)

diffs (249 lines):

diff -r d4df116b77ff -r 67d68beda2d3 lib/librumpuser/rumpuser_pth.c
--- a/lib/librumpuser/rumpuser_pth.c    Sat Apr 27 13:25:09 2013 +0000
+++ b/lib/librumpuser/rumpuser_pth.c    Sat Apr 27 13:59:46 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: rumpuser_pth.c,v 1.12 2013/02/11 16:02:31 pooka Exp $  */
+/*     $NetBSD: rumpuser_pth.c,v 1.13 2013/04/27 13:59:46 pooka Exp $  */
 
 /*
  * Copyright (c) 2007-2010 Antti Kantee.  All Rights Reserved.
@@ -28,7 +28,7 @@
 #include "rumpuser_port.h"
 
 #if !defined(lint)
-__RCSID("$NetBSD: rumpuser_pth.c,v 1.12 2013/02/11 16:02:31 pooka Exp $");
+__RCSID("$NetBSD: rumpuser_pth.c,v 1.13 2013/04/27 13:59:46 pooka Exp $");
 #endif /* !lint */
 
 #include <assert.h>
@@ -58,10 +58,12 @@
        }                                                               \
 } while (/*CONSTCOND*/0)
 
+#define MTX_KMUTEX 0x1
+#define MTX_ISSPIN 0x2
 struct rumpuser_mtx {
        pthread_mutex_t pthmtx;
        struct lwp *owner;
-       int iskmutex;
+       int flags;
 };
 
 #define RURW_AMWRITER(rw) (rw->writer == rumpuser_get_curlwp()         \
@@ -295,22 +297,22 @@
        pthread_mutexattr_destroy(&att);
 
        (*mtx)->owner = NULL;
-       (*mtx)->iskmutex = 0;
+       (*mtx)->flags = MTX_ISSPIN;
 }
 
 void
-rumpuser_mutex_init_kmutex(struct rumpuser_mtx **mtx)
+rumpuser_mutex_init_kmutex(struct rumpuser_mtx **mtx, int isspin)
 {
 
        rumpuser_mutex_init(mtx);
-       (*mtx)->iskmutex = 1;
+       (*mtx)->flags = MTX_KMUTEX | (isspin ? MTX_ISSPIN : 0);
 }
 
 static void
 mtxenter(struct rumpuser_mtx *mtx)
 {
 
-       if (!mtx->iskmutex)
+       if (!(mtx->flags & MTX_KMUTEX))
                return;
 
        assert(mtx->owner == NULL);
@@ -321,7 +323,7 @@
 mtxexit(struct rumpuser_mtx *mtx)
 {
 
-       if (!mtx->iskmutex)
+       if (!(mtx->flags & MTX_KMUTEX))
                return;
 
        assert(mtx->owner != NULL);
@@ -332,6 +334,11 @@
 rumpuser_mutex_enter(struct rumpuser_mtx *mtx)
 {
 
+       if (mtx->flags & MTX_ISSPIN) {
+               rumpuser_mutex_enter_nowrap(mtx);
+               return;
+       }
+
        if (pthread_mutex_trylock(&mtx->pthmtx) != 0)
                KLOCK_WRAP(NOFAIL_ERRNO(pthread_mutex_lock(&mtx->pthmtx)));
        mtxenter(mtx);
@@ -341,6 +348,7 @@
 rumpuser_mutex_enter_nowrap(struct rumpuser_mtx *mtx)
 {
 
+       assert(mtx->flags & MTX_ISSPIN);
        NOFAIL_ERRNO(pthread_mutex_lock(&mtx->pthmtx));
        mtxenter(mtx);
 }
@@ -378,7 +386,7 @@
 rumpuser_mutex_owner(struct rumpuser_mtx *mtx)
 {
 
-       if (__predict_false(!mtx->iskmutex)) {
+       if (__predict_false(!(mtx->flags & MTX_KMUTEX))) {
                printf("panic: rumpuser_mutex_held unsupported on non-kmtx\n");
                abort();
        }
diff -r d4df116b77ff -r 67d68beda2d3 lib/librumpuser/rumpuser_pth_dummy.c
--- a/lib/librumpuser/rumpuser_pth_dummy.c      Sat Apr 27 13:25:09 2013 +0000
+++ b/lib/librumpuser/rumpuser_pth_dummy.c      Sat Apr 27 13:59:46 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: rumpuser_pth_dummy.c,v 1.7 2012/11/06 18:33:00 pooka Exp $     */
+/*     $NetBSD: rumpuser_pth_dummy.c,v 1.8 2013/04/27 13:59:46 pooka Exp $     */
 
 /*
  * Copyright (c) 2009 Antti Kantee.  All Rights Reserved.
@@ -29,7 +29,7 @@
 
 #include <sys/cdefs.h>
 #if !defined(lint)
-__RCSID("$NetBSD: rumpuser_pth_dummy.c,v 1.7 2012/11/06 18:33:00 pooka Exp $");
+__RCSID("$NetBSD: rumpuser_pth_dummy.c,v 1.8 2013/04/27 13:59:46 pooka Exp $");
 #endif /* !lint */
 
 #include <sys/time.h>
@@ -111,7 +111,7 @@
 }
 
 void
-rumpuser_mutex_init_kmutex(struct rumpuser_mtx **mtx)
+rumpuser_mutex_init_kmutex(struct rumpuser_mtx **mtx, int isspin)
 {
 
        *mtx = calloc(1, sizeof(struct rumpuser_mtx));
diff -r d4df116b77ff -r 67d68beda2d3 sys/rump/include/rump/rumpuser.h
--- a/sys/rump/include/rump/rumpuser.h  Sat Apr 27 13:25:09 2013 +0000
+++ b/sys/rump/include/rump/rumpuser.h  Sat Apr 27 13:59:46 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: rumpuser.h,v 1.75 2013/03/08 19:04:28 pooka Exp $      */
+/*     $NetBSD: rumpuser.h,v 1.76 2013/04/27 13:59:46 pooka Exp $      */
 
 /*
  * Copyright (c) 2007-2011 Antti Kantee.  All Rights Reserved.
@@ -38,7 +38,7 @@
 #include <stdint.h>
 #endif
 
-#define RUMPUSER_VERSION 15
+#define RUMPUSER_VERSION 16
 int rumpuser_getversion(void);
 
 int rumpuser_daemonize_begin(void);
@@ -143,7 +143,7 @@
 struct rumpuser_mtx;
 
 void rumpuser_mutex_init(struct rumpuser_mtx **);
-void rumpuser_mutex_init_kmutex(struct rumpuser_mtx **);
+void rumpuser_mutex_init_kmutex(struct rumpuser_mtx **, int);
 void rumpuser_mutex_enter(struct rumpuser_mtx *);
 void rumpuser_mutex_enter_nowrap(struct rumpuser_mtx *);
 int  rumpuser_mutex_tryenter(struct rumpuser_mtx *);
diff -r d4df116b77ff -r 67d68beda2d3 sys/rump/librump/rumpkern/locks.c
--- a/sys/rump/librump/rumpkern/locks.c Sat Apr 27 13:25:09 2013 +0000
+++ b/sys/rump/librump/rumpkern/locks.c Sat Apr 27 13:59:46 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: locks.c,v 1.55 2011/12/06 18:04:31 njoly Exp $ */
+/*     $NetBSD: locks.c,v 1.56 2013/04/27 13:59:46 pooka Exp $ */
 
 /*
  * Copyright (c) 2007-2011 Antti Kantee.  All Rights Reserved.
@@ -26,7 +26,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: locks.c,v 1.55 2011/12/06 18:04:31 njoly Exp $");
+__KERNEL_RCSID(0, "$NetBSD: locks.c,v 1.56 2013/04/27 13:59:46 pooka Exp $");
 
 #include <sys/param.h>
 #include <sys/kmem.h>
@@ -90,10 +90,29 @@
 void
 mutex_init(kmutex_t *mtx, kmutex_type_t type, int ipl)
 {
+       int isspin;
+
+       /*
+        * Try to figure out if the caller wanted a spin mutex or
+        * not with this easy set of conditionals.  The difference
+        * between a spin mutex and an adaptive mutex for a rump
+        * kernel is that the hypervisor does not relinquish the
+        * rump kernel CPU context for a spin mutex.  The
+        * hypervisor itself may block even when "spinning".
+        */
+       if (type == MUTEX_SPIN) {
+               isspin = 1;
+       } else if (ipl == IPL_NONE || ipl == IPL_SOFTCLOCK ||
+           ipl == IPL_SOFTBIO || ipl == IPL_SOFTNET ||
+           ipl == IPL_SOFTSERIAL) {
+               isspin = 0;
+       } else {
+               isspin = 1;
+       }
 
        CTASSERT(sizeof(kmutex_t) >= sizeof(void *));
 
-       rumpuser_mutex_init_kmutex((struct rumpuser_mtx **)mtx);
+       rumpuser_mutex_init_kmutex((struct rumpuser_mtx **)mtx, isspin);
        ALLOCK(mtx, &mutex_lockops);
 }
 
@@ -113,7 +132,15 @@
        rumpuser_mutex_enter(RUMPMTX(mtx));
        LOCKED(mtx, false);
 }
-__strong_alias(mutex_spin_enter,mutex_enter);
+
+void
+mutex_spin_enter(kmutex_t *mtx)
+{
+
+       WANTLOCK(mtx, false, false);
+       rumpuser_mutex_enter_nowrap(RUMPMTX(mtx));
+       LOCKED(mtx, false);
+}
 
 int
 mutex_tryenter(kmutex_t *mtx)
diff -r d4df116b77ff -r 67d68beda2d3 sys/rump/librump/rumpkern/locks_up.c
--- a/sys/rump/librump/rumpkern/locks_up.c      Sat Apr 27 13:25:09 2013 +0000
+++ b/sys/rump/librump/rumpkern/locks_up.c      Sat Apr 27 13:59:46 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: locks_up.c,v 1.6 2012/04/28 18:04:02 stacktic Exp $    */
+/*     $NetBSD: locks_up.c,v 1.7 2013/04/27 13:59:46 pooka Exp $       */
 
 /*
  * Copyright (c) 2010 Antti Kantee.  All Rights Reserved.
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: locks_up.c,v 1.6 2012/04/28 18:04:02 stacktic Exp $");
+__KERNEL_RCSID(0, "$NetBSD: locks_up.c,v 1.7 2013/04/27 13:59:46 pooka Exp $");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -71,6 +71,13 @@
        checkncpu();
 
        /*
+        * In uniprocessor locking we don't need to differentiate
+        * between spin mutexes and adaptive ones.  We could
+        * replace mutex_enter() with a NOP for spin mutexes, but
+        * not bothering with that for now.
+        */
+
+       /*
         * XXX: pool_cache would be nice, but not easily possible,
         * as pool cache init wants to call mutex_init() ...
         */