[src/trunk]: src/sys/rump/librump/rumpkern When allocating the temporary lwp ...

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

details:   https://anonhg.NetBSD.org/src/rev/abe0d486abd9
branches:  trunk
changeset: 748194:abe0d486abd9
user:      pooka <pooka%NetBSD.org@localhost>
date:      Thu Oct 15 23:15:55 2009 +0000

description:
When allocating the temporary lwp we must have an lwp context.  So
take turns using lwp0 for this purpose, nothing else uses it.

diffstat:

 sys/rump/librump/rumpkern/locks.c        |   8 ++--
 sys/rump/librump/rumpkern/rump_private.h |  12 +++---
 sys/rump/librump/rumpkern/scheduler.c    |  50 ++++++++++++++++++++++++-------
 3 files changed, 49 insertions(+), 21 deletions(-)

diffs (165 lines):

diff -r cdf05b0b9840 -r abe0d486abd9 sys/rump/librump/rumpkern/locks.c
--- a/sys/rump/librump/rumpkern/locks.c Thu Oct 15 23:12:53 2009 +0000
+++ b/sys/rump/librump/rumpkern/locks.c Thu Oct 15 23:15:55 2009 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: locks.c,v 1.30 2009/10/15 16:39:22 pooka Exp $ */
+/*     $NetBSD: locks.c,v 1.31 2009/10/15 23:15:55 pooka Exp $ */
 
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -55,7 +55,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: locks.c,v 1.30 2009/10/15 16:39:22 pooka Exp $");
+__KERNEL_RCSID(0, "$NetBSD: locks.c,v 1.31 2009/10/15 23:15:55 pooka Exp $");
 
 #include <sys/param.h>
 #include <sys/atomic.h>
@@ -347,7 +347,7 @@
 
                        rump_unschedule_cpu(l);
                        rumpuser_mutex_enter_nowrap(rump_giantlock);
-                       rump_schedule_cpu(l);
+                       l->l_cpu = rump_schedule_cpu();
                }
                lockcnt++;
        }
@@ -391,7 +391,7 @@
 rump_user_schedule(int nlocks)
 {
 
-       rump_schedule_cpu(curlwp);
+       curlwp->l_cpu = rump_schedule_cpu();
 
        if (nlocks)
                _kernel_lock(nlocks);
diff -r cdf05b0b9840 -r abe0d486abd9 sys/rump/librump/rumpkern/rump_private.h
--- a/sys/rump/librump/rumpkern/rump_private.h  Thu Oct 15 23:12:53 2009 +0000
+++ b/sys/rump/librump/rumpkern/rump_private.h  Thu Oct 15 23:15:55 2009 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: rump_private.h,v 1.32 2009/10/15 16:39:22 pooka Exp $  */
+/*     $NetBSD: rump_private.h,v 1.33 2009/10/15 23:15:55 pooka Exp $  */
 
 /*
  * Copyright (c) 2007 Antti Kantee.  All Rights Reserved.
@@ -86,11 +86,11 @@
 int            rump_sysproxy_copyout(const void *, void *, size_t);
 int            rump_sysproxy_copyin(const void *, void *, size_t);
 
-void   rump_scheduler_init(void);
-void   rump_schedule(void);
-void   rump_unschedule(void);
-void   rump_schedule_cpu(struct lwp *);
-void   rump_unschedule_cpu(struct lwp *);
+void           rump_scheduler_init(void);
+void           rump_schedule(void);
+void           rump_unschedule(void);
+struct cpu_info *rump_schedule_cpu(void);
+void           rump_unschedule_cpu(struct lwp *);
 
 void   rump_user_schedule(int);
 void   rump_user_unschedule(int, int *);
diff -r cdf05b0b9840 -r abe0d486abd9 sys/rump/librump/rumpkern/scheduler.c
--- a/sys/rump/librump/rumpkern/scheduler.c     Thu Oct 15 23:12:53 2009 +0000
+++ b/sys/rump/librump/rumpkern/scheduler.c     Thu Oct 15 23:15:55 2009 +0000
@@ -1,4 +1,4 @@
-/*      $NetBSD: scheduler.c,v 1.2 2009/10/15 16:39:22 pooka Exp $     */
+/*      $NetBSD: scheduler.c,v 1.3 2009/10/15 23:15:55 pooka Exp $     */
 
 /*
  * Copyright (c) 2009 Antti Kantee.  All Rights Reserved.
@@ -29,7 +29,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: scheduler.c,v 1.2 2009/10/15 16:39:22 pooka Exp $");
+__KERNEL_RCSID(0, "$NetBSD: scheduler.c,v 1.3 2009/10/15 23:15:55 pooka Exp $");
 
 #include <sys/param.h>
 #include <sys/cpu.h>
@@ -53,7 +53,9 @@
 
 static SLIST_HEAD(,rumpcpu) cpu_freelist = SLIST_HEAD_INITIALIZER(cpu_freelist);
 static struct rumpuser_mtx *schedmtx;
-static struct rumpuser_cv *schedcv;
+static struct rumpuser_cv *schedcv, *lwp0cv;
+
+static bool lwp0busy = false;
 
 struct cpu_info *
 cpu_lookup(u_int index)
@@ -71,6 +73,7 @@
 
        rumpuser_mutex_init(&schedmtx);
        rumpuser_cv_init(&schedcv);
+       rumpuser_cv_init(&lwp0cv);
        for (i = 0; i < ncpu; i++) {
                rcpu = &rcpu_storage[i];
                ci = &rump_cpus[i];
@@ -83,32 +86,57 @@
 void
 rump_schedule()
 {
-       struct lwp *l = rumpuser_get_curlwp();
+       struct cpu_info *ci;
+       struct lwp *l;
 
        /*
         * If there is no dedicated lwp, allocate a temp one and
-        * set it to be free'd upon unschedule().
+        * set it to be free'd upon unschedule().  Use lwp0 context
+        * for reserving the necessary resources.
         */
+       l = rumpuser_get_curlwp();
        if (l == NULL) {
+               /* busy lwp0 */
+               rumpuser_mutex_enter_nowrap(schedmtx);
+               while (lwp0busy)
+                       rumpuser_cv_wait_nowrap(lwp0cv, schedmtx);
+               lwp0busy = true;
+               rumpuser_mutex_exit(schedmtx);
+
+               /* schedule cpu and use lwp0 */
+               ci = rump_schedule_cpu();
+               lwp0.l_cpu = ci;
+               rumpuser_set_curlwp(&lwp0);
                l = rump_lwp_alloc(0, rump_nextlid());
-               rumpuser_set_curlwp(l);
+
+               /* release lwp0 */
+               rump_lwp_switch(l);
+               rumpuser_mutex_enter_nowrap(schedmtx);
+               lwp0busy = false;
+               rumpuser_cv_signal(lwp0cv);
+               rumpuser_mutex_exit(schedmtx);
+
+               /* mark new lwp as dead-on-exit */
                rump_lwp_release(l);
+       } else {
+               KASSERT(l->l_cpu == NULL);
+               ci = rump_schedule_cpu();
+               l->l_cpu = ci;
        }
-       rump_schedule_cpu(l);
 }
 
-void
-rump_schedule_cpu(struct lwp *l)
+struct cpu_info *
+rump_schedule_cpu()
 {
        struct rumpcpu *rcpu;
 
-       KASSERT(l->l_cpu == NULL);
        rumpuser_mutex_enter_nowrap(schedmtx);
        while ((rcpu = SLIST_FIRST(&cpu_freelist)) == NULL)
                rumpuser_cv_wait_nowrap(schedcv, schedmtx);
        SLIST_REMOVE_HEAD(&cpu_freelist, rcpu_entries);
        rumpuser_mutex_exit(schedmtx);
-       l->l_cpu = rcpu->rcpu_ci;
+
+       return rcpu->rcpu_ci;
 }
 
 void