mirror of
git://sourceware.org/git/newlib-cygwin.git
synced 2025-01-19 12:59:21 +08:00
717c36c0a4
while debugging a problem introduced in commit
63b503916d42 ("Cygwin: tls_pathbuf: Use Windows heap")
a hang in fork was encountered using the original implementation
of tls_pathbuf:
Using tmp_pathbuf inside the code block guarded by __malloc_trylock
may call malloc from tmp_pathbuf::w_get and thus trying to lock an
exclusive SRW lock recursively, which results in a deadlock.
Allocate a small SECURITY_ATTRIBUTES block on the stack rather than
allocating a 64K tmp_pathbuf. This avoids the potential malloc call.
Drop the __malloc_trylock call entirely. There must not be a malloc
call inside the frok::parent block guarded by __malloc_lock, and
just trying to lock is too dangerous inside fork while other threads
might actually chage the content of the heap. Additionally, add a
comment frowning on malloc usage inside tis code block.
Fixes: 44a79a6eca3d ("Cygwin: convert malloc lock to SRWLOCK")
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
44 lines
1.0 KiB
C
44 lines
1.0 KiB
C
/* cygmalloc.h: cygwin DLL malloc stuff
|
|
|
|
This file is part of Cygwin.
|
|
|
|
This software is a copyrighted work licensed under the terms of the
|
|
Cygwin license. Please consult the file "CYGWIN_LICENSE" for
|
|
details. */
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
void dlfree (void *p);
|
|
void *dlmalloc (size_t size);
|
|
void *dlrealloc (void *p, size_t size);
|
|
void *dlcalloc (size_t nmemb, size_t size);
|
|
void *dlmemalign (size_t alignment, size_t bytes);
|
|
void *dlvalloc (size_t bytes);
|
|
size_t dlmalloc_usable_size (void *p);
|
|
int dlmalloc_trim (size_t);
|
|
int dlmallopt (int p, int v);
|
|
void dlmalloc_stats ();
|
|
|
|
#define MALLOC_ALIGNMENT ((size_t)16U)
|
|
|
|
#if defined (DLMALLOC_VERSION) /* Building malloc.cc */
|
|
|
|
extern "C" void __set_ENOMEM ();
|
|
# define MALLOC_FAILURE_ACTION __set_ENOMEM ()
|
|
# define USE_DL_PREFIX 1
|
|
|
|
#elif defined (__INSIDE_CYGWIN__)
|
|
|
|
# define __malloc_lock() AcquireSRWLockExclusive (&mallock)
|
|
# define __malloc_unlock() ReleaseSRWLockExclusive (&mallock)
|
|
extern SRWLOCK NO_COPY mallock;
|
|
void malloc_init ();
|
|
|
|
#endif
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|