File fix-locking-in-_IO_cleanup.patch of Package glibc.18276
Always do locking when accessing streams
[BZ #15142]
* include/libio.h (_IO_ftrylockfile) [_IO_MTSAVE_IO]: Define.
* libio/genops.c (_IO_list_all_stamp): Delete. All uses removed.
* libio/genops.c (_IO_flush_all_lockp): Make static. Rename
argument to skip_locked, callers changed. Skip files that are
locked if skip_locked.
(_IO_unbuffer_all): Lock files before access, but skip locked
files.
* libio/libioP.h (_IO_flush_all_all_lockp): Don't declare.
Index: glibc-2.26/include/libio.h
===================================================================
--- glibc-2.26.orig/include/libio.h
+++ glibc-2.26/include/libio.h
@@ -33,11 +33,15 @@ libc_hidden_proto (_IO_vfscanf)
if (((_fp)->_flags & _IO_USER_LOCK) == 0) _IO_lock_lock (*(_fp)->_lock)
# define _IO_funlockfile(_fp) \
if (((_fp)->_flags & _IO_USER_LOCK) == 0) _IO_lock_unlock (*(_fp)->_lock)
+# define _IO_ftrylockfile(_fp) \
+ (((_fp)->_flags & _IO_USER_LOCK) == 0 ? _IO_lock_trylock (*(_fp)->_lock) : 0)
# else
# define _IO_flockfile(_fp) \
if (((_fp)->_flags & _IO_USER_LOCK) == 0) _IO_flockfile (_fp)
# define _IO_funlockfile(_fp) \
if (((_fp)->_flags & _IO_USER_LOCK) == 0) _IO_funlockfile (_fp)
+# define _IO_ftrylockfile(_fp) \
+ (((_fp)->_flags & _IO_USER_LOCK) == 0 ? _IO_ftrylockfile (_fp) : 0)
# endif
#endif /* _IO_MTSAFE_IO */
Index: glibc-2.26/libio/genops.c
===================================================================
--- glibc-2.26.orig/libio/genops.c
+++ glibc-2.26/libio/genops.c
@@ -38,10 +38,6 @@
static _IO_lock_t list_all_lock = _IO_lock_initializer;
#endif
-/* Used to signal modifications to the list of FILE decriptors. */
-static int _IO_list_all_stamp;
-
-
static _IO_FILE *run_fp;
#ifdef _IO_MTSAFE_IO
@@ -69,16 +65,12 @@ _IO_un_link (struct _IO_FILE_plus *fp)
if (_IO_list_all == NULL)
;
else if (fp == _IO_list_all)
- {
- _IO_list_all = (struct _IO_FILE_plus *) _IO_list_all->file._chain;
- ++_IO_list_all_stamp;
- }
+ _IO_list_all = (struct _IO_FILE_plus *) _IO_list_all->file._chain;
else
for (f = &_IO_list_all->file._chain; *f; f = &(*f)->_chain)
if (*f == (_IO_FILE *) fp)
{
*f = fp->file._chain;
- ++_IO_list_all_stamp;
break;
}
fp->file._flags &= ~_IO_LINKED;
@@ -106,7 +98,6 @@ _IO_link_in (struct _IO_FILE_plus *fp)
#endif
fp->file._chain = (_IO_FILE *) _IO_list_all;
_IO_list_all = fp;
- ++_IO_list_all_stamp;
#ifdef _IO_MTSAFE_IO
_IO_funlockfile ((_IO_FILE *) fp);
run_fp = NULL;
@@ -789,25 +780,30 @@ _IO_get_column (_IO_FILE *fp)
#endif
-int
-_IO_flush_all_lockp (int do_lock)
+static int
+_IO_flush_all_lockp (bool skip_locked)
{
int result = 0;
struct _IO_FILE *fp;
- int last_stamp;
#ifdef _IO_MTSAFE_IO
- __libc_cleanup_region_start (do_lock, flush_cleanup, NULL);
- if (do_lock)
- _IO_lock_lock (list_all_lock);
+ _IO_cleanup_region_start_noarg (flush_cleanup);
+ _IO_lock_lock (list_all_lock);
#endif
- last_stamp = _IO_list_all_stamp;
- fp = (_IO_FILE *) _IO_list_all;
- while (fp != NULL)
+ for (fp = (_IO_FILE *) _IO_list_all; fp != NULL; fp = fp->_chain)
{
run_fp = fp;
- if (do_lock)
+ if (skip_locked)
+ {
+ /* Skip files that are currently locked. */
+ if (_IO_ftrylockfile (fp))
+ {
+ run_fp = NULL;
+ continue;
+ }
+ }
+ else
_IO_flockfile (fp);
if (((fp->_mode <= 0 && fp->_IO_write_ptr > fp->_IO_write_base)
@@ -820,24 +816,13 @@ _IO_flush_all_lockp (int do_lock)
&& _IO_OVERFLOW (fp, EOF) == EOF)
result = EOF;
- if (do_lock)
- _IO_funlockfile (fp);
+ _IO_funlockfile (fp);
run_fp = NULL;
-
- if (last_stamp != _IO_list_all_stamp)
- {
- /* Something was added to the list. Start all over again. */
- fp = (_IO_FILE *) _IO_list_all;
- last_stamp = _IO_list_all_stamp;
- }
- else
- fp = fp->_chain;
}
#ifdef _IO_MTSAFE_IO
- if (do_lock)
- _IO_lock_unlock (list_all_lock);
- __libc_cleanup_region_end (0);
+ _IO_lock_unlock (list_all_lock);
+ _IO_cleanup_region_end (0);
#endif
return result;
@@ -848,7 +833,7 @@ int
_IO_flush_all (void)
{
/* We want locking. */
- return _IO_flush_all_lockp (1);
+ return _IO_flush_all_lockp (false);
}
libc_hidden_def (_IO_flush_all)
@@ -856,16 +841,13 @@ void
_IO_flush_all_linebuffered (void)
{
struct _IO_FILE *fp;
- int last_stamp;
#ifdef _IO_MTSAFE_IO
_IO_cleanup_region_start_noarg (flush_cleanup);
_IO_lock_lock (list_all_lock);
#endif
- last_stamp = _IO_list_all_stamp;
- fp = (_IO_FILE *) _IO_list_all;
- while (fp != NULL)
+ for (fp = (_IO_FILE *) _IO_list_all; fp != NULL; fp = fp->_chain)
{
run_fp = fp;
_IO_flockfile (fp);
@@ -875,15 +857,6 @@ _IO_flush_all_linebuffered (void)
_IO_funlockfile (fp);
run_fp = NULL;
-
- if (last_stamp != _IO_list_all_stamp)
- {
- /* Something was added to the list. Start all over again. */
- fp = (_IO_FILE *) _IO_list_all;
- last_stamp = _IO_list_all_stamp;
- }
- else
- fp = fp->_chain;
}
#ifdef _IO_MTSAFE_IO
@@ -919,24 +892,26 @@ static void
_IO_unbuffer_all (void)
{
struct _IO_FILE *fp;
+
+#ifdef _IO_MTSAFE_IO
+ _IO_cleanup_region_start_noarg (flush_cleanup);
+ _IO_lock_lock (list_all_lock);
+#endif
+
for (fp = (_IO_FILE *) _IO_list_all; fp; fp = fp->_chain)
{
+ run_fp = fp;
+ /* Skip files that are currently locked. */
+ if (_IO_ftrylockfile (fp))
+ {
+ run_fp = NULL;
+ continue;
+ }
+
if (! (fp->_flags & _IO_UNBUFFERED)
/* Iff stream is un-orientated, it wasn't used. */
&& fp->_mode != 0)
{
-#ifdef _IO_MTSAFE_IO
- int cnt;
-#define MAXTRIES 2
- for (cnt = 0; cnt < MAXTRIES; ++cnt)
- if (fp->_lock == NULL || _IO_lock_trylock (*fp->_lock) == 0)
- break;
- else
- /* Give the other thread time to finish up its use of the
- stream. */
- __sched_yield ();
-#endif
-
if (! dealloc_buffers && !(fp->_flags & _IO_USER_BUF))
{
fp->_flags |= _IO_USER_BUF;
@@ -950,17 +925,20 @@ _IO_unbuffer_all (void)
if (fp->_mode > 0)
_IO_wsetb (fp, NULL, NULL, 0);
-
-#ifdef _IO_MTSAFE_IO
- if (cnt < MAXTRIES && fp->_lock != NULL)
- _IO_lock_unlock (*fp->_lock);
-#endif
}
/* Make sure that never again the wide char functions can be
used. */
fp->_mode = -1;
+
+ _IO_funlockfile (fp);
+ run_fp = NULL;
}
+
+#ifdef _IO_MTSAFE_IO
+ _IO_lock_unlock (list_all_lock);
+ _IO_cleanup_region_end (0);
+#endif
}
@@ -980,9 +958,9 @@ libc_freeres_fn (buffer_free)
int
_IO_cleanup (void)
{
- /* We do *not* want locking. Some threads might use streams but
- that is their problem, we flush them underneath them. */
- int result = _IO_flush_all_lockp (0);
+ /* We want to skip locked streams. Some threads might use streams but
+ that is their problem, we don't flush those. */
+ int result = _IO_flush_all_lockp (true);
/* We currently don't have a reliable mechanism for making sure that
C++ static destructors are executed in the correct order.
Index: glibc-2.26/libio/libioP.h
===================================================================
--- glibc-2.26.orig/libio/libioP.h
+++ glibc-2.26/libio/libioP.h
@@ -507,7 +507,6 @@ extern int _IO_new_do_write (_IO_FILE *,
extern int _IO_old_do_write (_IO_FILE *, const char *, _IO_size_t);
extern int _IO_wdo_write (_IO_FILE *, const wchar_t *, _IO_size_t);
libc_hidden_proto (_IO_wdo_write)
-extern int _IO_flush_all_lockp (int);
extern int _IO_flush_all (void);
libc_hidden_proto (_IO_flush_all)
extern int _IO_cleanup (void);
