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* fhandler.h (refcnt): Add i interlocked. Explain why. 

* winbase.h (ilockadd): New function.
	(InterlockedAdd): Define as ilockadd.
This commit is contained in:
Corinna Vinschen 2012-05-23 13:13:56 +00:00
parent 420b3469a7
commit 2ca9ed527e
3 changed files with 29 additions and 2 deletions
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6
winsup/cygwin/ChangeLog
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@ -1,3 +1,9 @@
2012-05-23 Corinna Vinschen <corinna@vinschen.de>
* fhandler.h (refcnt): Add i interlocked. Explain why.
* winbase.h (ilockadd): New function.
(InterlockedAdd): Define as ilockadd.
2012-05-22 Corinna Vinschen <corinna@vinschen.de> 2012-05-22 Corinna Vinschen <corinna@vinschen.de>
* devices.in: Fix native name of /dev/kmem. * devices.in: Fix native name of /dev/kmem.

6
winsup/cygwin/fhandler.h
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@ -185,7 +185,11 @@ class fhandler_base
long refcnt(long i = 0) long refcnt(long i = 0)
{ {
debug_only_printf ("%p, %s, i %d, refcnt %ld", this, get_name (), i, _refcnt + i); debug_only_printf ("%p, %s, i %d, refcnt %ld", this, get_name (), i, _refcnt + i);
return _refcnt += i; /* This MUST be an interlocked operation. If multiple threads access the
same descriptor in quick succession, a context switch can interrupt
the += operation and we wrongly end up with a refcnt of 0 in the
cygheap_fdget destructor. */
return i ? InterlockedAdd (&_refcnt, i) : _refcnt;
} }
class fhandler_base *archetype; class fhandler_base *archetype;
int usecount; int usecount;

19
winsup/cygwin/winbase.h
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@ -1,6 +1,6 @@
/* winbase.h /* winbase.h
Copyright 2002, 2003, 2004, 2008 Red Hat, Inc. Copyright 2002, 2003, 2004, 2008, 2012 Red Hat, Inc.
This software is a copyrighted work licensed under the terms of the This software is a copyrighted work licensed under the terms of the
Cygwin license. Please consult the file "CYGWIN_LICENSE" for Cygwin license. Please consult the file "CYGWIN_LICENSE" for
@ -11,6 +11,21 @@ details. */
#ifndef _WINBASE2_H #ifndef _WINBASE2_H
#define _WINBASE2_H #define _WINBASE2_H
/* For some unknown reason, InterlockedAdd is only supported on Itanium
when using the Windows headers. Fortunately we're not restricted to the
Windows headers :) */
extern __inline__ long
ilockadd (volatile long *m, long value)
{
register int __res;
__asm__ __volatile__ ("\n\
movl %3,%0\n\
lock xadd %0,%1\n\
addl %3,%0\n\
": "=&r" (__res), "=m" (*m): "m" (*m), "r" (value): "cc");
return __res;
}
extern __inline__ long extern __inline__ long
ilockincr (volatile long *m) ilockincr (volatile long *m)
{ {
@ -65,6 +80,8 @@ ilockcmpexch (volatile long *t, long v, long c)
}); });
} }
#undef InterlockedAdd
#define InterlockedAdd ilockadd
#undef InterlockedIncrement #undef InterlockedIncrement
#define InterlockedIncrement ilockincr #define InterlockedIncrement ilockincr
#undef InterlockedDecrement #undef InterlockedDecrement