[src/trunk]: src/external/cddl/osnet/sys/sys our pool code needs either PR_SL...

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

details:   https://anonhg.NetBSD.org/src/rev/76a781890bf5
branches:  trunk
changeset: 357611:76a781890bf5
user:      christos <christos%NetBSD.org@localhost>
date:      Fri Nov 17 18:18:01 2017 +0000

description:
our pool code needs either PR_SLEEP or PR_NOWAIT; arrange for that explaining
the current choice :-)

diffstat:

 external/cddl/osnet/sys/sys/kmem.h |  27 ++++++++++++++++++++++++---
 1 files changed, 24 insertions(+), 3 deletions(-)

diffs (50 lines):

diff -r 89838e9cd783 -r 76a781890bf5 external/cddl/osnet/sys/sys/kmem.h
--- a/external/cddl/osnet/sys/sys/kmem.h        Fri Nov 17 16:44:01 2017 +0000
+++ b/external/cddl/osnet/sys/sys/kmem.h        Fri Nov 17 18:18:01 2017 +0000
@@ -1,5 +1,5 @@
 
-/*     $NetBSD: kmem.h,v 1.6 2010/02/21 01:46:36 darran Exp $  */
+/*     $NetBSD: kmem.h,v 1.7 2017/11/17 18:18:01 christos Exp $        */
 
 /*-
  * Copyright (c) 2009 The NetBSD Foundation, Inc.
@@ -43,7 +43,7 @@
 u_long kmem_used(void);
 void   kmem_reap(void);
 
-void   *calloc(size_t n, size_t s);
+void   *calloc(size_t, size_t);
 
 static inline kmem_cache_t *
 kmem_cache_create(char *name, size_t bufsize, size_t align,
@@ -62,8 +62,29 @@
        return pc;
 }
 
+static inline void *
+kmem_cache_alloc(kmem_cache_t *cache, int flags)
+{
+       /*
+        * This happens when we specify KM_PUSHPAGE by itself.
+        *
+        * According to kmem_cache_create(9) KM_PUSHPAGE can be used
+        * together with KM_SLEEP and in that case the code will not
+        * cause a deadlock. It does not say if KM_PUSHPAGE can be
+        * used with KM_NOSLEEP. In our case, we don't have a pool
+        * of emergency pages, so we prefer to KM_SLEEP instead of
+        * using KM_NOSLEEP and potentially returning NULL, under the
+        * assumption that the code wants to use the emergency pool
+        * because it does not want the allocation to fail. If that
+        * causes a deadlock we either need to provide an emergency
+        * pool or handle the failure.
+        */
+       if (flags == 0)
+               flags |= KM_SLEEP;
+       return pool_cache_get(cache, flags);
+}
+
 #define        kmem_cache_destroy(cache)               pool_cache_destroy(cache)
-#define        kmem_cache_alloc(cache, flags)          pool_cache_get(cache, flags)
 #define        kmem_cache_free(cache, buf)             pool_cache_put(cache, buf)
 #define        kmem_cache_reap_now(cache)              pool_cache_invalidate(cache)