Aren
/
NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Switch atform allocations from malloc()+free() to mmap()+munmap() 

This avoid bootstrapping malloc too early when libc+libpthread are not
ready. It is called through pthread__init() -> _pthread_atfork().

This also helps LLVM Leak Sanitizer to pacify false positive reports.
This commit is contained in:
kamil 2020-02-01 15:38:46 +00:00
parent df2a83facc
commit 089c97bd22
1 changed files with 18 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
lib/libc/gen/pthread_atfork.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: pthread_atfork.c,v 1.10 2015/01/20 18:31:25 christos Exp $ */
/* $NetBSD: pthread_atfork.c,v 1.11 2020/02/01 15:38:46 kamil Exp $ */
/*-
* Copyright (c) 2002 The NetBSD Foundation, Inc.
@ -31,15 +31,17 @@
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: pthread_atfork.c,v 1.10 2015/01/20 18:31:25 christos Exp $");
__RCSID("$NetBSD: pthread_atfork.c,v 1.11 2020/02/01 15:38:46 kamil Exp $");
#endif /* LIBC_SCCS and not lint */
#include "namespace.h"
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/queue.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/queue.h>
#include "reentrant.h"
#ifdef __weak_alias
@ -73,11 +75,22 @@ static struct atfork_callback_q childq = SIMPLEQ_HEAD_INITIALIZER(childq);
static struct atfork_callback *
af_alloc(void)
{
void *arena;
size_t sz;
if (atfork_builtin.fn == NULL)
return &atfork_builtin;
return malloc(sizeof(atfork_builtin));
/*
* Avoid using here malloc() as this function is used on early init
* and can prematuraly initialize the malloc library.
* malloc() allocations here also confuse the LLVM Leak Sanitizer.
*/
sz = sizeof(atfork_builtin);
arena = mmap(NULL, sz, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
if (arena == MAP_FAILED)
return NULL;
return arena;
}
static void
@ -85,7 +98,7 @@ af_free(struct atfork_callback *af)
{
if (af != &atfork_builtin)
free(af);
munmap(af, sizeof(atfork_builtin));
}
int