Module Name: src
Committed By: christos
Date: Sat Mar 1 18:19:50 UTC 2025
Modified Files:
src/lib/libc/gen: pthread_atfork.c
Log Message:
keep a cache of 3 entries so that we don't have to call malloc(3) from
libpthread which can't call malloc from a constructor.
To generate a diff of this commit:
cvs rdiff -u -r1.21 -r1.22 src/lib/libc/gen/pthread_atfork.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/lib/libc/gen/pthread_atfork.c
diff -u src/lib/libc/gen/pthread_atfork.c:1.21 src/lib/libc/gen/pthread_atfork.c:1.22
--- src/lib/libc/gen/pthread_atfork.c:1.21 Sat Mar 1 11:34:03 2025
+++ src/lib/libc/gen/pthread_atfork.c Sat Mar 1 13:19:50 2025
@@ -1,4 +1,4 @@
-/* $NetBSD: pthread_atfork.c,v 1.21 2025/03/01 16:34:03 christos Exp $ */
+/* $NetBSD: pthread_atfork.c,v 1.22 2025/03/01 18:19:50 christos Exp $ */
/*-
* Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
-__RCSID("$NetBSD: pthread_atfork.c,v 1.21 2025/03/01 16:34:03 christos Exp $");
+__RCSID("$NetBSD: pthread_atfork.c,v 1.22 2025/03/01 18:19:50 christos Exp $");
#endif /* LIBC_SCCS and not lint */
#include "namespace.h"
@@ -59,13 +59,20 @@ struct atfork_callback {
void (*fn)(void);
};
+
+/*
+ * Keep a cache for of 3, one for prepare, one for parent, one for child.
+ * This is so that we don't have to allocate memory for the call from the
+ * pthread_tsd_init() constructor, where it is too early to call malloc(3).
+ */
+static struct atfork_callback atfork_builtin[3];
+
/*
* Hypothetically, we could protect the queues with a rwlock which is
* write-locked by pthread_atfork() and read-locked by fork(), but
* since the intended use of the functions is obtaining locks to hold
* across the fork, forking is going to be serialized anyway.
*/
-static struct atfork_callback atfork_builtin;
#ifdef _REENTRANT
static mutex_t atfork_lock = MUTEX_INITIALIZER;
#endif
@@ -78,9 +85,10 @@ static struct atfork_callback_q childq =
static struct atfork_callback *
af_alloc(void)
{
-
- if (atfork_builtin.fn == NULL)
- return &atfork_builtin;
+ for (size_t i = 0; i < __arraycount(atfork_builtin); i++) {
+ if (atfork_builtin[i].fn == NULL)
+ return &atfork_builtin[i];
+ }
return malloc(sizeof(atfork_builtin));
}
@@ -88,9 +96,14 @@ af_alloc(void)
static void
af_free(struct atfork_callback *af)
{
-
- if (af != &atfork_builtin)
- free(af);
+ for (size_t i = 0; i < __arraycount(atfork_builtin); i++) {
+ if (af == &atfork_builtin[i]) {
+ atfork_builtin[i].fn = NULL;
+ return;
+ }
+ }
+
+ free(af);
}
int
