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From: "fweimer at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug stdio/15142] Missing locking in _IO_cleanup
Date: Wed, 13 Mar 2024 10:23:23 +0000 [thread overview]
Message-ID: <bug-15142-131-zChwKjcG95@http.sourceware.org/bugzilla/> (raw)
In-Reply-To: <bug-15142-131@http.sourceware.org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=15142
--- Comment #7 from Florian Weimer <fweimer at redhat dot com> ---
(In reply to Dmitry Vyukov from comment #6)
> We started getting hangs on the following program:
>
> https://github.com/llvm/llvm-project/blob/
> 995d1d114e4e4ff708a03cdb0a975209c6197f9f/compiler-rt/test/tsan/
> getline_nohang.cpp#L28
>
> Basically just calls a blocking getline in one thread and another thread
> tries to exit.
It's blocking on this:
FILE *stream = fdopen(fd[0], "r");
while (1) {
volatile int res = getline(&line, &size, stream);
(void)res;
}
It's not a writable stream, so we could avoid the blocking with a more complex
handshake between stdio streams and exit. I'm not sure if it's worth doing
that. We could perhaps add another flag to fopen/fdopen that indicates that
the stream should not participate in fflush (NULL) or exit flushing.
For streams which are blocked in writing, POSIX does not really give us a way
to make forward progress because we have to flush the unwritten data before
exiting.
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next prev parent reply other threads:[~2024-03-13 10:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-13 13:12 [Bug stdio/15142] New: " schwab@linux-m68k.org
2013-02-14 20:13 ` [Bug stdio/15142] " bugdal at aerifal dot cx
2014-03-25 9:24 ` schwab@linux-m68k.org
2014-06-13 18:49 ` fweimer at redhat dot com
2023-06-04 22:16 ` ppluzhnikov at google dot com
2023-07-03 9:08 ` fweimer at redhat dot com
2024-03-13 10:13 ` dvyukov at google dot com
2024-03-13 10:23 ` fweimer at redhat dot com [this message]
2024-03-13 10:28 ` dvyukov at google dot com
2024-03-13 10:43 ` fweimer at redhat dot com
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