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| author | Takashi Yano <takashi.yano@nifty.ne.jp> | 2025-07-16 23:21:17 +0900 |
|---|---|---|
| committer | Takashi Yano <takashi.yano@nifty.ne.jp> | 2025-07-17 00:14:42 +0900 |
| commit | e8bc312a2d32a465260e38f948d91f2847a1d00a (patch) | |
| tree | b3e03fb8b6d0e874f72d739399651a7d578a2977 | |
| parent | 3dfa6af3a41b71cacbcf9cf7495c4032845383d4 (diff) | |
| download | newlib-e8bc312a2d32a465260e38f948d91f2847a1d00a.zip newlib-e8bc312a2d32a465260e38f948d91f2847a1d00a.tar.gz newlib-e8bc312a2d32a465260e38f948d91f2847a1d00a.tar.bz2 | |
newlib: fclose: Use sfp lock while fp lock is active
With the commit 656df313e08a, if a thread acquires sfp lock after
another thread calls fclose() and fp lock is acquired, the first
thread falls into deadlock if it tries to acquire fp lock. This can
happen if the first thread calls __sfp_lock_all() while the second
thread calls fclose().
This patch reverts the changes for newlib/libc/stdio/fclose.c in
the commit 656df313e08a.
Addresses: https://cygwin.com/pipermail/cygwin/2025-June/258323.html
Fixes: 656df313e08a ("* libc/stdio/fclose.c: Only use sfp lock to guard non-atomic changes of flags and fp lock.")
Reported-by: Takashi Yano <takashi.yano@nifty.ne.jp>
Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
| -rw-r--r-- | newlib/libc/stdio/fclose.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/newlib/libc/stdio/fclose.c b/newlib/libc/stdio/fclose.c index 983ae2c..4c81cbf 100644 --- a/newlib/libc/stdio/fclose.c +++ b/newlib/libc/stdio/fclose.c @@ -72,6 +72,7 @@ _fclose_r (struct _reent *rptr, int __oldcancel; pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &__oldcancel); #endif + __sfp_lock_acquire (); if (!(fp->_flags2 & __SNLK)) _flockfile (fp); @@ -79,6 +80,7 @@ _fclose_r (struct _reent *rptr, { if (!(fp->_flags2 & __SNLK)) _funlockfile (fp); + __sfp_lock_release (); #ifdef _STDIO_WITH_THREAD_CANCELLATION_SUPPORT pthread_setcancelstate (__oldcancel, &__oldcancel); #endif @@ -101,7 +103,6 @@ _fclose_r (struct _reent *rptr, FREEUB (rptr, fp); if (HASLB (fp)) FREELB (rptr, fp); - __sfp_lock_acquire (); fp->_flags = 0; /* release this FILE for reuse */ if (!(fp->_flags2 & __SNLK)) _funlockfile (fp); |