[src/trunk]: src/sys Turn PA_INITIALIZED to a reference count for the pool al...

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

details:   https://anonhg.NetBSD.org/src/rev/506eaab374dd
branches:  trunk
changeset: 750411:506eaab374dd
user:      elad <elad%NetBSD.org@localhost>
date:      Wed Dec 30 18:57:16 2009 +0000

description:
Turn PA_INITIALIZED to a reference count for the pool allocator, and once
it drops to zero destroy the mutex we initialize. This fixes the problem
mentioned in

        http://mail-index.netbsd.org/tech-kern/2009/12/28/msg006727.html

Also remove pa_flags now that it's no longer needed.

Idea from matt@, okay matt@.

diffstat:

 sys/kern/subr_pool.c |  19 +++++++++++++++----
 sys/sys/pool.h       |   5 ++---
 2 files changed, 17 insertions(+), 7 deletions(-)

diffs (88 lines):

diff -r 718f277f4887 -r 506eaab374dd sys/kern/subr_pool.c
--- a/sys/kern/subr_pool.c      Wed Dec 30 18:39:03 2009 +0000
+++ b/sys/kern/subr_pool.c      Wed Dec 30 18:57:16 2009 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: subr_pool.c,v 1.177 2009/10/20 17:24:22 jym Exp $      */
+/*     $NetBSD: subr_pool.c,v 1.178 2009/12/30 18:57:17 elad Exp $     */
 
 /*-
  * Copyright (c) 1997, 1999, 2000, 2002, 2007, 2008 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_pool.c,v 1.177 2009/10/20 17:24:22 jym Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_pool.c,v 1.178 2009/12/30 18:57:17 elad Exp $");
 
 #include "opt_ddb.h"
 #include "opt_pool.h"
@@ -104,6 +104,9 @@
 static kmutex_t pool_head_lock;
 static kcondvar_t pool_busy;
 
+/* This lock protects initialization of a potentially shared pool allocator */
+static kmutex_t pool_allocator_lock;
+
 typedef uint32_t pool_item_bitmap_t;
 #define        BITMAP_SIZE     (CHAR_BIT * sizeof(pool_item_bitmap_t))
 #define        BITMAP_MASK     (BITMAP_SIZE - 1)
@@ -604,6 +607,8 @@
 
        pool_init(&cache_cpu_pool, sizeof(pool_cache_cpu_t), coherency_unit,
            0, 0, "pcachecpu", &pool_allocator_nointr, IPL_NONE);
+
+       mutex_init(&pool_allocator_lock, MUTEX_DEFAULT, IPL_NONE);
 }
 
 /*
@@ -650,7 +655,8 @@
                        palloc = &pool_allocator_nointr_fullpage;
        }               
 #endif /* POOL_SUBPAGE */
-       if ((palloc->pa_flags & PA_INITIALIZED) == 0) {
+       mutex_enter(&pool_allocator_lock);
+       if (palloc->pa_refcnt++ == 0) {
                if (palloc->pa_pagesz == 0)
                        palloc->pa_pagesz = PAGE_SIZE;
 
@@ -663,8 +669,8 @@
                if (palloc->pa_backingmapptr != NULL) {
                        pa_reclaim_register(palloc);
                }
-               palloc->pa_flags |= PA_INITIALIZED;
        }
+       mutex_exit(&pool_allocator_lock);
 
        if (align == 0)
                align = ALIGN(1);
@@ -892,6 +898,11 @@
        TAILQ_REMOVE(&pp->pr_alloc->pa_list, pp, pr_alloc_list);
        mutex_exit(&pp->pr_alloc->pa_lock);
 
+       mutex_enter(&pool_allocator_lock);
+       if (--pp->pr_alloc->pa_refcnt == 0)
+               mutex_destroy(&pp->pr_alloc->pa_lock);
+       mutex_exit(&pool_allocator_lock);
+
        mutex_enter(&pp->pr_lock);
 
        KASSERT(pp->pr_cache == NULL);
diff -r 718f277f4887 -r 506eaab374dd sys/sys/pool.h
--- a/sys/sys/pool.h    Wed Dec 30 18:39:03 2009 +0000
+++ b/sys/sys/pool.h    Wed Dec 30 18:57:16 2009 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pool.h,v 1.67 2009/10/15 20:50:12 thorpej Exp $        */
+/*     $NetBSD: pool.h,v 1.68 2009/12/30 18:57:16 elad Exp $   */
 
 /*-
  * Copyright (c) 1997, 1998, 1999, 2000, 2007 The NetBSD Foundation, Inc.
@@ -63,8 +63,7 @@
        /* The following fields are for internal use only. */
        kmutex_t        pa_lock;
        TAILQ_HEAD(, pool) pa_list;     /* list of pools using this allocator */
-       int             pa_flags;
-#define        PA_INITIALIZED  0x01
+       uint32_t        pa_refcnt;      /* number of pools using this allocator */
        int             pa_pagemask;
        int             pa_pageshift;
        struct vm_map *pa_backingmap;