From: Torvald Riegel <triegel@redhat.com>
To: Martin Sebor <msebor@redhat.com>
Cc: Florian Weimer <fweimer@redhat.com>,
GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [PATCH] pthread_once hangs when init routine throws an exception [BZ #18435]
Date: Wed, 03 Jun 2015 11:36:00 -0000 [thread overview]
Message-ID: <1433329653.21461.104.camel@triegel.csb> (raw)
In-Reply-To: <556C8062.4010309@redhat.com>
On Mon, 2015-06-01 at 09:55 -0600, Martin Sebor wrote:
> On 06/01/2015 02:38 AM, Florian Weimer wrote:
> > It's not immediately obvious to me why this change works. :)
>
> The pthread_cleanup_push and pthread_cleanup_pop macros are
> defined in sysdeps/nptl/pthread.h. In C code outside of
> glibc compiled with -fexceptions (with __EXCEPTIONS defined),
> they make use of GCC attribute cleanup to invoke the cleanup
> handler during stack unwinding. (In C++ they make use of
> a destructor of a class object.) These macros do the right
> thing when an exception is thrown in the code they surround.
>
> The problem is that the nptl/pthreadP.h header redefines
> the macros for internal use by glibc without the use of
> the cleanup attribute. As a result, when an exception is
> thrown, the cleanup handler is not invoked. This is what
> happens in pthread_once.c.
>
> By removing the macro redefinitions from nptl/pthreadP.h
> the change causes pthread_once.c to be compiled with the
> more robust macros defined in pthread.h and allows cleanup
> to take place even after an exception has been thrown so
> long as glibc has been compiled with -fexceptions.
This sounds reasonable for me, but I don't know enough about this to
know for sure :)
I agree with the motivation of the change (ie, making it possible for
libstdc++ to use pthread_once in the implementation); I haven't looked
at this in detail, but your arguments regarding C/C++ compatibility that
you made elsewhere in the thread seemed fine for me.
next prev parent reply other threads:[~2015-06-03 11:07 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <556B7F10.40209@redhat.com>
2015-06-01 8:39 ` Florian Weimer
2015-06-01 16:27 ` Martin Sebor
2015-06-02 9:53 ` Mike Frysinger
2015-06-04 21:12 ` Martin Sebor
2015-06-03 11:36 ` Torvald Riegel [this message]
2015-06-01 10:20 ` Szabolcs Nagy
2015-06-01 19:47 ` Martin Sebor
2015-06-03 11:07 ` Torvald Riegel
2015-06-03 11:11 ` Jonathan Wakely
2015-06-03 20:14 ` Rich Felker
2015-06-03 20:24 ` Martin Sebor
2015-06-03 23:49 ` Rich Felker
2015-06-04 1:47 ` Martin Sebor
2015-06-04 5:38 ` Rich Felker
2015-06-04 7:29 ` Martin Sebor
2015-06-08 11:41 ` Jonathan Wakely
2015-06-08 14:38 ` Szabolcs Nagy
2015-06-04 8:20 ` Torvald Riegel
2015-06-08 11:48 ` Jonathan Wakely
2015-06-08 16:01 ` Florian Weimer
2015-06-03 11:07 ` Torvald Riegel
2015-06-01 14:39 ` Andreas Schwab
2015-06-09 19:49 ` Martin Sebor
2015-06-15 22:14 ` Martin Sebor
2015-06-23 7:48 ` [PING 2] " Martin Sebor
[not found] ` <5593256B.5060402@redhat.com>
2015-07-01 0:06 ` [PING 3] " Rich Felker
2015-07-01 20:18 ` Martin Sebor
2015-07-01 21:27 ` Joseph Myers
2015-07-06 13:18 ` Szabolcs Nagy
2015-07-06 14:16 ` Martin Sebor
2015-07-06 14:58 ` Adhemerval Zanella
2015-07-06 16:33 ` Szabolcs Nagy
2015-07-06 17:09 ` Szabolcs Nagy
2015-07-08 11:00 ` Szabolcs Nagy
2015-07-08 16:09 ` Carlos O'Donell
2015-07-08 16:33 ` Torvald Riegel
2015-07-08 16:52 ` Szabolcs Nagy
2015-07-08 17:14 ` Carlos O'Donell
2021-03-02 16:43 ` Jakub Jelinek
2015-07-08 16:16 ` Carlos O'Donell
2015-07-08 21:28 ` Martin Sebor
2015-07-08 22:13 ` Szabolcs Nagy
2015-07-08 22:52 ` Martin Sebor
2015-07-08 23:42 ` Szabolcs Nagy
2015-07-09 4:46 ` Martin Sebor
2015-07-09 23:41 ` Martin Sebor
2021-03-03 12:52 Jakub Jelinek
2021-03-04 11:50 ` Florian Weimer
2021-03-04 13:00 ` Jakub Jelinek
2021-03-04 13:26 ` Florian Weimer
2021-03-04 14:14 ` Jakub Jelinek
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