[src/trunk]: src/sys/kern Use uint64_t for the unbound and per-cpu thread poo...

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

details:   https://anonhg.NetBSD.org/src/rev/0eb20c905f2e
branches:  trunk
changeset: 446957:0eb20c905f2e
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Wed Dec 26 20:08:22 2018 +0000

description:
Use uint64_t for the unbound and per-cpu thread pool ref counts; they're
always manipulated under a lock.  Rather than bother returning EBUSY,
just assert that the ref count never overlows (if it ever does, you have
bigger problems).

diffstat:

 sys/kern/kern_threadpool.c |  28 ++++++++++------------------
 1 files changed, 10 insertions(+), 18 deletions(-)

diffs (88 lines):

diff -r c46e86b45d33 -r 0eb20c905f2e sys/kern/kern_threadpool.c
--- a/sys/kern/kern_threadpool.c        Wed Dec 26 19:54:09 2018 +0000
+++ b/sys/kern/kern_threadpool.c        Wed Dec 26 20:08:22 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_threadpool.c,v 1.4 2018/12/26 18:54:19 thorpej Exp $      */
+/*     $NetBSD: kern_threadpool.c,v 1.5 2018/12/26 20:08:22 thorpej Exp $      */
 
 /*-
  * Copyright (c) 2014, 2018 The NetBSD Foundation, Inc.
@@ -81,7 +81,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_threadpool.c,v 1.4 2018/12/26 18:54:19 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_threadpool.c,v 1.5 2018/12/26 20:08:22 thorpej Exp $");
 
 #include <sys/types.h>
 #include <sys/param.h>
@@ -161,7 +161,7 @@
 
        /* protected by threadpools_lock */
        LIST_ENTRY(threadpool_unbound)  tpu_link;
-       unsigned int                    tpu_refcnt;
+       uint64_t                        tpu_refcnt;
 };
 
 static LIST_HEAD(, threadpool_unbound) unbound_threadpools;
@@ -198,7 +198,7 @@
 
        /* protected by threadpools_lock */
        LIST_ENTRY(threadpool_percpu)   tpp_link;
-       unsigned int                    tpp_refcnt;
+       uint64_t                        tpp_refcnt;
 };
 
 static LIST_HEAD(, threadpool_percpu) percpu_threadpools;
@@ -428,13 +428,8 @@
                }
        }
        KASSERT(tpu != NULL);
-       if (tpu->tpu_refcnt == UINT_MAX) {
-               mutex_exit(&threadpools_lock);
-               if (tmp != NULL)
-                       threadpool_destroy(&tmp->tpu_pool, sizeof(*tpu));
-               return EBUSY;
-       }
        tpu->tpu_refcnt++;
+       KASSERT(tpu->tpu_refcnt != 0);
        mutex_exit(&threadpools_lock);
 
        if (tmp != NULL)
@@ -463,8 +458,9 @@
                TP_LOG(("%s: Last reference for pri=%d, destroying pool.\n",
                        __func__, (int)pri));
                threadpool_remove_unbound(tpu);
-       } else
+       } else {
                tpu = NULL;
+       }
        mutex_exit(&threadpools_lock);
 
        if (tpu)
@@ -507,13 +503,8 @@
                }
        }
        KASSERT(pool_percpu != NULL);
-       if (pool_percpu->tpp_refcnt == UINT_MAX) {
-               mutex_exit(&threadpools_lock);
-               if (tmp != NULL)
-                       threadpool_percpu_destroy(tmp);
-               return EBUSY;
-       }
        pool_percpu->tpp_refcnt++;
+       KASSERT(pool_percpu->tpp_refcnt != 0);
        mutex_exit(&threadpools_lock);
 
        if (tmp != NULL)
@@ -540,8 +531,9 @@
                TP_LOG(("%s: Last reference for pri=%d, destroying pool.\n",
                        __func__, (int)pri));
                threadpool_remove_percpu(pool_percpu);
-       } else
+       } else {
                pool_percpu = NULL;
+       }
        mutex_exit(&threadpools_lock);
 
        if (pool_percpu)