* libc/stdio/fclose.c: Only use sfp lock to guard non-atomic

	changes of flags and fp lock.
	* libc/stdio/freopen.c: Ditto.
	* libc/stdio/freopen64.c: Ditto.
	* libc/stdio/fgetc.c: Revert change from 2009-04-24, remove sfp locks
	which guard entire function to avoid potential deadlocks when using
	stdio functions in multiple thraeds.
	* libc/stdio/fgets.c: Ditto.
	* libc/stdio/fgetwc.c: Ditto.
	* libc/stdio/fgetws.c: Ditto.
	* libc/stdio/fread.c: Ditto.
	* libc/stdio/fseek.c: Ditto.
	* libc/stdio/getc.c: Ditto.
	* libc/stdio/getdelim.c: Ditto.
	* libc/stdio/gets.c: Ditto.
	* libc/stdio/vfscanf.c: Ditto.
	* libc/stdio/vfwscanf.c: Ditto.

	* libc/stdio/fflush.c (_fflush_r): Split out core functionality into
	new function __sflush_r.  Just lock file and call __sflush_r from here.
	* libc/stdio/fwalk.c (_fwalk): Remove static helper function and move
	functionality back into main function. Don't walk a file with flags
	value of 1.  Add comment.
	(_fwalk_reent): Ditto.
	* libc/stdio/local.h (__sflush_r): Declare.
	* libc/stdio/refill.c (__srefill): Before calling fwalk, set flags
	value to 1 so this file pointer isn't walked.  Revert flags afterwards
	and call __sflush_r for this fp if necessary.  Add comments.

1 files changed, 12 insertions, 2 deletions

diff --git a/newlib/libc/stdio/refill.c b/newlib/libc/stdio/refill.c
index 27266ce70..9d853f94d 100644
--- a/newlib/libc/stdio/refill.c
+++ b/newlib/libc/stdio/refill.c
@@ -102,9 +102,19 @@ _DEFUN(__srefill_r, (ptr, fp),
    * flush all line buffered output files, per the ANSI C
    * standard.
    */
-
   if (fp->_flags & (__SLBF | __SNBF))
-    _CAST_VOID _fwalk (_GLOBAL_REENT, lflush);
+    {
+      /* Ignore this file in _fwalk to avoid potential deadlock. */
+      short orig_flags = fp->_flags;
+      fp->_flags = 1;
+      _CAST_VOID _fwalk (_GLOBAL_REENT, lflush);
+      fp->_flags = orig_flags;
+
+      /* Now flush this file without locking it. */
+      if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
+	__sflush_r (ptr, fp);
+    }
+
   fp->_p = fp->_bf._base;
   fp->_r = fp->_read (ptr, fp->_cookie, (char *) fp->_p, fp->_bf._size);
 #ifndef __CYGWIN__