* Re: [PATCH] libstdc++/112351 - deal with __gthread_once failure during locale init [not found] <20231106115212.6DCC23858C00@sourceware.org> @ 2023-11-06 12:16 ` Jakub Jelinek 2023-11-06 12:17 ` Jonathan Wakely 0 siblings, 1 reply; 7+ messages in thread From: Jakub Jelinek @ 2023-11-06 12:16 UTC (permalink / raw) To: Richard Biener; +Cc: gcc-patches, libstdc++, jwakely On Mon, Nov 06, 2023 at 11:52:08AM +0000, Richard Biener wrote: > The following makes the C++98 locale init path follow the way the > C++11 performs initialization. This way we deal with pthread_once > failing, falling back to non-threadsafe initialization which, given we > initialize from the library, should be serialized by the dynamic > loader already. > > Bootstrapped and tested on x86_64-unknown-linux-gnu, OK for trunk? > And GCC 13 branch? > > Thanks, > Richard. > > PR libstdc++/112351 > libstdc++-v3/ > * src/c++98/locale.cc (locale::facet::_S_get_c_locale): > Always perform non-threadsafe init when threadsafe init > failed. > --- > libstdc++-v3/src/c++98/locale.cc | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/libstdc++-v3/src/c++98/locale.cc b/libstdc++-v3/src/c++98/locale.cc > index d308140bab7..e9bec1db3b6 100644 > --- a/libstdc++-v3/src/c++98/locale.cc > +++ b/libstdc++-v3/src/c++98/locale.cc > @@ -216,12 +216,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > #ifdef __GTHREADS > if (__gthread_active_p()) > __gthread_once(&_S_once, _S_initialize_once); > - else > #endif > - { > - if (!_S_c_locale) > - _S_initialize_once(); > - } > + if (__builtin_expect (!_S_c_locale, 0)) > + _S_initialize_once(); > return _S_c_locale; Wouldn't it be better to just test __gthread_once return value #ifdef __THREADS if ((!__gthread_active_p() || __gthread_once(&_S_once, _S_initialize_once))) #endif if (!_S_c_locale) _S_initialize_once(); ? Jakub ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] libstdc++/112351 - deal with __gthread_once failure during locale init 2023-11-06 12:16 ` [PATCH] libstdc++/112351 - deal with __gthread_once failure during locale init Jakub Jelinek @ 2023-11-06 12:17 ` Jonathan Wakely 0 siblings, 0 replies; 7+ messages in thread From: Jonathan Wakely @ 2023-11-06 12:17 UTC (permalink / raw) To: Jakub Jelinek; +Cc: Richard Biener, gcc-patches, libstdc++ On Mon, 6 Nov 2023 at 12:16, Jakub Jelinek <jakub@redhat.com> wrote: > > On Mon, Nov 06, 2023 at 11:52:08AM +0000, Richard Biener wrote: > > The following makes the C++98 locale init path follow the way the > > C++11 performs initialization. This way we deal with pthread_once > > failing, falling back to non-threadsafe initialization which, given we > > initialize from the library, should be serialized by the dynamic > > loader already. > > > > Bootstrapped and tested on x86_64-unknown-linux-gnu, OK for trunk? > > And GCC 13 branch? > > > > Thanks, > > Richard. > > > > PR libstdc++/112351 > > libstdc++-v3/ > > * src/c++98/locale.cc (locale::facet::_S_get_c_locale): > > Always perform non-threadsafe init when threadsafe init > > failed. > > --- > > libstdc++-v3/src/c++98/locale.cc | 7 ++----- > > 1 file changed, 2 insertions(+), 5 deletions(-) > > > > diff --git a/libstdc++-v3/src/c++98/locale.cc b/libstdc++-v3/src/c++98/locale.cc > > index d308140bab7..e9bec1db3b6 100644 > > --- a/libstdc++-v3/src/c++98/locale.cc > > +++ b/libstdc++-v3/src/c++98/locale.cc > > @@ -216,12 +216,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > > #ifdef __GTHREADS > > if (__gthread_active_p()) > > __gthread_once(&_S_once, _S_initialize_once); > > - else > > #endif > > - { > > - if (!_S_c_locale) > > - _S_initialize_once(); > > - } > > + if (__builtin_expect (!_S_c_locale, 0)) > > + _S_initialize_once(); > > return _S_c_locale; > > Wouldn't it be better to just test __gthread_once return value > #ifdef __THREADS > if ((!__gthread_active_p() > || __gthread_once(&_S_once, _S_initialize_once))) > #endif > if (!_S_c_locale) > _S_initialize_once(); > ? This still has the problem of calling the function twice, once because __gthread_once fails and one because it succeeds. ^ permalink raw reply [flat|nested] 7+ messages in thread
[parent not found: <11125.123110606520900751@us-mta-255.us.mimecast.lan>]
* Re: [PATCH] libstdc++/112351 - deal with __gthread_once failure during locale init [not found] <11125.123110606520900751@us-mta-255.us.mimecast.lan> @ 2023-11-06 12:15 ` Jonathan Wakely 2023-11-06 12:51 ` Richard Biener 0 siblings, 1 reply; 7+ messages in thread From: Jonathan Wakely @ 2023-11-06 12:15 UTC (permalink / raw) To: Richard Biener; +Cc: gcc-patches, libstdc++ On Mon, 6 Nov 2023 at 11:52, Richard Biener <rguenther@suse.de> wrote: > > The following makes the C++98 locale init path follow the way the > C++11 performs initialization. This way we deal with pthread_once > failing, falling back to non-threadsafe initialization which, given we > initialize from the library, should be serialized by the dynamic > loader already. > > Bootstrapped and tested on x86_64-unknown-linux-gnu, OK for trunk? > And GCC 13 branch? > > Thanks, > Richard. > > PR libstdc++/112351 > libstdc++-v3/ > * src/c++98/locale.cc (locale::facet::_S_get_c_locale): > Always perform non-threadsafe init when threadsafe init > failed. > --- > libstdc++-v3/src/c++98/locale.cc | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/libstdc++-v3/src/c++98/locale.cc b/libstdc++-v3/src/c++98/locale.cc > index d308140bab7..e9bec1db3b6 100644 > --- a/libstdc++-v3/src/c++98/locale.cc > +++ b/libstdc++-v3/src/c++98/locale.cc > @@ -216,12 +216,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > #ifdef __GTHREADS > if (__gthread_active_p()) > __gthread_once(&_S_once, _S_initialize_once); > - else > #endif > - { > - if (!_S_c_locale) > - _S_initialize_once(); > - } > + if (__builtin_expect (!_S_c_locale, 0)) > + _S_initialize_once(); > return _S_c_locale; > } I think this has a problem, which is handled correctly in src/c++11/locale_init.cc by checking _S_classic inside the _S_initialize_once function. If the first call to __gthread_once does fail then _S_once will not be changed. We will fall through to calling _S_initialize_once directly (which is not thread-safe) and set _S_c_locale. The next time we call _S_initialize, __gthread_once will try to run again, and because _S_once was not changed, it might call _S_initialize_once() again, which writes to _S_c_locale again (possibly causing a data race). I don't think the slightly different code in src/c++11/locale_init.cc is different in order to handle __gthread_once failing, I think it's different because the effects of locale::facet::_S_initialize_once() and locale::_S_initialize_once() are different. One is safe to call more than once, and the other isn't. I don't think we need to care about __gthread_once failing at all, do we? There are no error conditions for pthread_once, it always returns 0 (previous POSIX revisions said it could return EINVAL for an uninitialized pthread_once_t but that can't happen here as it's correctly initialized in src/c++11/locale.cc). Is the concern that it can fail for non-posix thread models? (I didn't check if any of them can actually fail) ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] libstdc++/112351 - deal with __gthread_once failure during locale init 2023-11-06 12:15 ` Jonathan Wakely @ 2023-11-06 12:51 ` Richard Biener 2023-11-07 10:55 ` Richard Biener 2023-11-07 11:44 ` Jonathan Wakely 0 siblings, 2 replies; 7+ messages in thread From: Richard Biener @ 2023-11-06 12:51 UTC (permalink / raw) To: Jonathan Wakely; +Cc: gcc-patches, libstdc++ On Mon, 6 Nov 2023, Jonathan Wakely wrote: > On Mon, 6 Nov 2023 at 11:52, Richard Biener <rguenther@suse.de> wrote: > > > > The following makes the C++98 locale init path follow the way the > > C++11 performs initialization. This way we deal with pthread_once > > failing, falling back to non-threadsafe initialization which, given we > > initialize from the library, should be serialized by the dynamic > > loader already. > > > > Bootstrapped and tested on x86_64-unknown-linux-gnu, OK for trunk? > > And GCC 13 branch? > > > > Thanks, > > Richard. > > > > PR libstdc++/112351 > > libstdc++-v3/ > > * src/c++98/locale.cc (locale::facet::_S_get_c_locale): > > Always perform non-threadsafe init when threadsafe init > > failed. > > --- > > libstdc++-v3/src/c++98/locale.cc | 7 ++----- > > 1 file changed, 2 insertions(+), 5 deletions(-) > > > > diff --git a/libstdc++-v3/src/c++98/locale.cc b/libstdc++-v3/src/c++98/locale.cc > > index d308140bab7..e9bec1db3b6 100644 > > --- a/libstdc++-v3/src/c++98/locale.cc > > +++ b/libstdc++-v3/src/c++98/locale.cc > > @@ -216,12 +216,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > > #ifdef __GTHREADS > > if (__gthread_active_p()) > > __gthread_once(&_S_once, _S_initialize_once); > > - else > > #endif > > - { > > - if (!_S_c_locale) > > - _S_initialize_once(); > > - } > > + if (__builtin_expect (!_S_c_locale, 0)) > > + _S_initialize_once(); > > return _S_c_locale; > > } > > > I think this has a problem, which is handled correctly in > src/c++11/locale_init.cc by checking _S_classic inside the > _S_initialize_once function. We check _S_c_locale here (it's just a pointer) instead of in _S_initialize_once (), so I think the code is equivalent, no? > If the first call to __gthread_once does fail then _S_once will not be > changed. We will fall through to calling _S_initialize_once directly > (which is not thread-safe) and set _S_c_locale. > > The next time we call _S_initialize, __gthread_once will try to run > again, and because _S_once was not changed, it might call > _S_initialize_once() again, which writes to _S_c_locale again > (possibly causing a data race). Ah, yeah, so in the C++11 path the check for !_S_classic in locale::_S_initialize is redundant. But good spot. > I don't think the slightly different code in src/c++11/locale_init.cc > is different in order to handle __gthread_once failing, I think it's > different because the effects of locale::facet::_S_initialize_once() > and locale::_S_initialize_once() are different. One is safe to call > more than once, and the other isn't. > > I don't think we need to care about __gthread_once failing at all, do > we? There are no error conditions for pthread_once, it always returns > 0 (previous POSIX revisions said it could return EINVAL for an > uninitialized pthread_once_t but that can't happen here as it's > correctly initialized in src/c++11/locale.cc). Is the concern that it > can fail for non-posix thread models? (I didn't check if any of them > can actually fail) The concern is that there are actual products out that break with the new I/O initialization in libstdc++ for GCC13+ because they have bugs. It's easy enough to work around those by the proposed patch (plus correction for the above issue). I suppose the comment in locale::_S_initialize_once holds as well for the C++98 path. The failure mode of the product is that it overrides pthread_once but does nothing (not even indicate failure) when its pthread_* override mechanism isn't initialized yet. With libstdc++ from GCC13 we now use pthread_once "too early" and fail to initialize the locale object. Adjusted patch below. OK after another round of testing? Thanks, Richard. From 4e3fa2f4426a5a10d189587b63e4d7298c347b01 Mon Sep 17 00:00:00 2001 From: Richard Biener <rguenther@suse.de> Date: Mon, 6 Nov 2023 11:31:40 +0100 Subject: [PATCH] libstdc++/112351 - deal with __gthread_once failure during locale init To: gcc-patches@gcc.gnu.org The following makes the C++98 locale init path follow the way the C++11 performs initialization. This way we deal with pthread_once failing, falling back to non-threadsafe initialization which, given we initialize from the library, should be serialized by the dynamic loader already. PR libstdc++/112351 libstdc++-v3/ * src/c++98/locale.cc (locale::facet::_S_initialize_once): Check whether _S_c_locale is already initialized. (locale::facet::_S_get_c_locale): Always perform non-threadsafe init when threadsafe init failed. --- libstdc++-v3/src/c++98/locale.cc | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/libstdc++-v3/src/c++98/locale.cc b/libstdc++-v3/src/c++98/locale.cc index d308140bab7..1ef0c394cd7 100644 --- a/libstdc++-v3/src/c++98/locale.cc +++ b/libstdc++-v3/src/c++98/locale.cc @@ -206,6 +206,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION void locale::facet::_S_initialize_once() { + // Need to check this because we could get called once from + // _S_get_c_locale() when the program is single-threaded, and then again + // (via __gthread_once) when it's multi-threaded. + if (_S_c_locale) + return; + // Initialize the underlying locale model. _S_create_c_locale(_S_c_locale, _S_c_name); } @@ -216,12 +222,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION #ifdef __GTHREADS if (__gthread_active_p()) __gthread_once(&_S_once, _S_initialize_once); - else #endif - { - if (!_S_c_locale) - _S_initialize_once(); - } + if (__builtin_expect (!_S_c_locale, 0)) + _S_initialize_once(); return _S_c_locale; } -- 2.35.3 ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] libstdc++/112351 - deal with __gthread_once failure during locale init 2023-11-06 12:51 ` Richard Biener @ 2023-11-07 10:55 ` Richard Biener 2023-11-07 11:44 ` Jonathan Wakely 1 sibling, 0 replies; 7+ messages in thread From: Richard Biener @ 2023-11-07 10:55 UTC (permalink / raw) To: Jonathan Wakely; +Cc: gcc-patches, libstdc++ On Mon, 6 Nov 2023, Richard Biener wrote: > On Mon, 6 Nov 2023, Jonathan Wakely wrote: > > > On Mon, 6 Nov 2023 at 11:52, Richard Biener <rguenther@suse.de> wrote: > > > > > > The following makes the C++98 locale init path follow the way the > > > C++11 performs initialization. This way we deal with pthread_once > > > failing, falling back to non-threadsafe initialization which, given we > > > initialize from the library, should be serialized by the dynamic > > > loader already. > > > > > > Bootstrapped and tested on x86_64-unknown-linux-gnu, OK for trunk? > > > And GCC 13 branch? > > > > > > Thanks, > > > Richard. [.. old patch ..] > > The next time we call _S_initialize, __gthread_once will try to run > > again, and because _S_once was not changed, it might call > > _S_initialize_once() again, which writes to _S_c_locale again > > (possibly causing a data race). > > Ah, yeah, so in the C++11 path the check for !_S_classic in > locale::_S_initialize is redundant. But good spot. > > > I don't think the slightly different code in src/c++11/locale_init.cc > > is different in order to handle __gthread_once failing, I think it's > > different because the effects of locale::facet::_S_initialize_once() > > and locale::_S_initialize_once() are different. One is safe to call > > more than once, and the other isn't. > > > > I don't think we need to care about __gthread_once failing at all, do > > we? There are no error conditions for pthread_once, it always returns > > 0 (previous POSIX revisions said it could return EINVAL for an > > uninitialized pthread_once_t but that can't happen here as it's > > correctly initialized in src/c++11/locale.cc). Is the concern that it > > can fail for non-posix thread models? (I didn't check if any of them > > can actually fail) > > The concern is that there are actual products out that break with the > new I/O initialization in libstdc++ for GCC13+ because they have bugs. > It's easy enough to work around those by the proposed patch (plus > correction for the above issue). I suppose the comment in > locale::_S_initialize_once holds as well for the C++98 path. > > The failure mode of the product is that it overrides pthread_once > but does nothing (not even indicate failure) when its pthread_* > override mechanism isn't initialized yet. With libstdc++ from GCC13 > we now use pthread_once "too early" and fail to initialize the locale > object. > > Adjusted patch below. > > OK after another round of testing? Bootstrapped and tested on x86_64-unknown-linux-gnu. OK? Thanks, Richard. > Thanks, > Richard. > > > From 4e3fa2f4426a5a10d189587b63e4d7298c347b01 Mon Sep 17 00:00:00 2001 > From: Richard Biener <rguenther@suse.de> > Date: Mon, 6 Nov 2023 11:31:40 +0100 > Subject: [PATCH] libstdc++/112351 - deal with __gthread_once failure during > locale init > To: gcc-patches@gcc.gnu.org > > The following makes the C++98 locale init path follow the way the > C++11 performs initialization. This way we deal with pthread_once > failing, falling back to non-threadsafe initialization which, given we > initialize from the library, should be serialized by the dynamic > loader already. > > PR libstdc++/112351 > libstdc++-v3/ > * src/c++98/locale.cc (locale::facet::_S_initialize_once): > Check whether _S_c_locale is already initialized. > (locale::facet::_S_get_c_locale): Always perform non-threadsafe > init when threadsafe init failed. > --- > libstdc++-v3/src/c++98/locale.cc | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/libstdc++-v3/src/c++98/locale.cc b/libstdc++-v3/src/c++98/locale.cc > index d308140bab7..1ef0c394cd7 100644 > --- a/libstdc++-v3/src/c++98/locale.cc > +++ b/libstdc++-v3/src/c++98/locale.cc > @@ -206,6 +206,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > void > locale::facet::_S_initialize_once() > { > + // Need to check this because we could get called once from > + // _S_get_c_locale() when the program is single-threaded, and then again > + // (via __gthread_once) when it's multi-threaded. > + if (_S_c_locale) > + return; > + > // Initialize the underlying locale model. > _S_create_c_locale(_S_c_locale, _S_c_name); > } > @@ -216,12 +222,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > #ifdef __GTHREADS > if (__gthread_active_p()) > __gthread_once(&_S_once, _S_initialize_once); > - else > #endif > - { > - if (!_S_c_locale) > - _S_initialize_once(); > - } > + if (__builtin_expect (!_S_c_locale, 0)) > + _S_initialize_once(); > return _S_c_locale; > } > > ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] libstdc++/112351 - deal with __gthread_once failure during locale init 2023-11-06 12:51 ` Richard Biener 2023-11-07 10:55 ` Richard Biener @ 2023-11-07 11:44 ` Jonathan Wakely 1 sibling, 0 replies; 7+ messages in thread From: Jonathan Wakely @ 2023-11-07 11:44 UTC (permalink / raw) To: Richard Biener; +Cc: gcc-patches, libstdc++ On Mon, 6 Nov 2023 at 12:52, Richard Biener <rguenther@suse.de> wrote: > > On Mon, 6 Nov 2023, Jonathan Wakely wrote: > > > On Mon, 6 Nov 2023 at 11:52, Richard Biener <rguenther@suse.de> wrote: > > > > > > The following makes the C++98 locale init path follow the way the > > > C++11 performs initialization. This way we deal with pthread_once > > > failing, falling back to non-threadsafe initialization which, given we > > > initialize from the library, should be serialized by the dynamic > > > loader already. > > > > > > Bootstrapped and tested on x86_64-unknown-linux-gnu, OK for trunk? > > > And GCC 13 branch? > > > > > > Thanks, > > > Richard. > > > > > > PR libstdc++/112351 > > > libstdc++-v3/ > > > * src/c++98/locale.cc (locale::facet::_S_get_c_locale): > > > Always perform non-threadsafe init when threadsafe init > > > failed. > > > --- > > > libstdc++-v3/src/c++98/locale.cc | 7 ++----- > > > 1 file changed, 2 insertions(+), 5 deletions(-) > > > > > > diff --git a/libstdc++-v3/src/c++98/locale.cc b/libstdc++-v3/src/c++98/locale.cc > > > index d308140bab7..e9bec1db3b6 100644 > > > --- a/libstdc++-v3/src/c++98/locale.cc > > > +++ b/libstdc++-v3/src/c++98/locale.cc > > > @@ -216,12 +216,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > > > #ifdef __GTHREADS > > > if (__gthread_active_p()) > > > __gthread_once(&_S_once, _S_initialize_once); > > > - else > > > #endif > > > - { > > > - if (!_S_c_locale) > > > - _S_initialize_once(); > > > - } > > > + if (__builtin_expect (!_S_c_locale, 0)) > > > + _S_initialize_once(); > > > return _S_c_locale; > > > } > > > > > > I think this has a problem, which is handled correctly in > > src/c++11/locale_init.cc by checking _S_classic inside the > > _S_initialize_once function. > > We check _S_c_locale here (it's just a pointer) instead of in It's a __locale_struct* for glibc and int* for BSD. Hopefully it's always something pointer-ish so that works. > _S_initialize_once (), so I think the code is equivalent, no? > > > If the first call to __gthread_once does fail then _S_once will not be > > changed. We will fall through to calling _S_initialize_once directly > > (which is not thread-safe) and set _S_c_locale. > > > > The next time we call _S_initialize, __gthread_once will try to run > > again, and because _S_once was not changed, it might call > > _S_initialize_once() again, which writes to _S_c_locale again > > (possibly causing a data race). > > Ah, yeah, so in the C++11 path the check for !_S_classic in > locale::_S_initialize is redundant. But good spot. Redundant, but it avoids a call to _S_initialize_once, so probably worth it for performance. > > > I don't think the slightly different code in src/c++11/locale_init.cc > > is different in order to handle __gthread_once failing, I think it's > > different because the effects of locale::facet::_S_initialize_once() > > and locale::_S_initialize_once() are different. One is safe to call > > more than once, and the other isn't. > > > > I don't think we need to care about __gthread_once failing at all, do > > we? There are no error conditions for pthread_once, it always returns > > 0 (previous POSIX revisions said it could return EINVAL for an > > uninitialized pthread_once_t but that can't happen here as it's > > correctly initialized in src/c++11/locale.cc). Is the concern that it > > can fail for non-posix thread models? (I didn't check if any of them > > can actually fail) > > The concern is that there are actual products out that break with the > new I/O initialization in libstdc++ for GCC13+ because they have bugs. > It's easy enough to work around those by the proposed patch (plus > correction for the above issue). I suppose the comment in > locale::_S_initialize_once holds as well for the C++98 path. > > The failure mode of the product is that it overrides pthread_once > but does nothing (not even indicate failure) when its pthread_* > override mechanism isn't initialized yet. With libstdc++ from GCC13 > we now use pthread_once "too early" and fail to initialize the locale > object. > > Adjusted patch below. > > OK after another round of testing? OK, thanks. > > Thanks, > Richard. > > > From 4e3fa2f4426a5a10d189587b63e4d7298c347b01 Mon Sep 17 00:00:00 2001 > From: Richard Biener <rguenther@suse.de> > Date: Mon, 6 Nov 2023 11:31:40 +0100 > Subject: [PATCH] libstdc++/112351 - deal with __gthread_once failure during > locale init > To: gcc-patches@gcc.gnu.org > > The following makes the C++98 locale init path follow the way the > C++11 performs initialization. This way we deal with pthread_once > failing, falling back to non-threadsafe initialization which, given we > initialize from the library, should be serialized by the dynamic > loader already. > > PR libstdc++/112351 > libstdc++-v3/ > * src/c++98/locale.cc (locale::facet::_S_initialize_once): > Check whether _S_c_locale is already initialized. > (locale::facet::_S_get_c_locale): Always perform non-threadsafe > init when threadsafe init failed. > --- > libstdc++-v3/src/c++98/locale.cc | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/libstdc++-v3/src/c++98/locale.cc b/libstdc++-v3/src/c++98/locale.cc > index d308140bab7..1ef0c394cd7 100644 > --- a/libstdc++-v3/src/c++98/locale.cc > +++ b/libstdc++-v3/src/c++98/locale.cc > @@ -206,6 +206,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > void > locale::facet::_S_initialize_once() > { > + // Need to check this because we could get called once from > + // _S_get_c_locale() when the program is single-threaded, and then again > + // (via __gthread_once) when it's multi-threaded. > + if (_S_c_locale) > + return; > + > // Initialize the underlying locale model. > _S_create_c_locale(_S_c_locale, _S_c_name); > } > @@ -216,12 +222,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > #ifdef __GTHREADS > if (__gthread_active_p()) > __gthread_once(&_S_once, _S_initialize_once); > - else > #endif > - { > - if (!_S_c_locale) > - _S_initialize_once(); > - } > + if (__builtin_expect (!_S_c_locale, 0)) > + _S_initialize_once(); > return _S_c_locale; > } > > -- > 2.35.3 > ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH] libstdc++/112351 - deal with __gthread_once failure during locale init @ 2023-11-06 11:52 Richard Biener 0 siblings, 0 replies; 7+ messages in thread From: Richard Biener @ 2023-11-06 11:52 UTC (permalink / raw) To: gcc-patches; +Cc: libstdc++, jwakely The following makes the C++98 locale init path follow the way the C++11 performs initialization. This way we deal with pthread_once failing, falling back to non-threadsafe initialization which, given we initialize from the library, should be serialized by the dynamic loader already. Bootstrapped and tested on x86_64-unknown-linux-gnu, OK for trunk? And GCC 13 branch? Thanks, Richard. PR libstdc++/112351 libstdc++-v3/ * src/c++98/locale.cc (locale::facet::_S_get_c_locale): Always perform non-threadsafe init when threadsafe init failed. --- libstdc++-v3/src/c++98/locale.cc | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/libstdc++-v3/src/c++98/locale.cc b/libstdc++-v3/src/c++98/locale.cc index d308140bab7..e9bec1db3b6 100644 --- a/libstdc++-v3/src/c++98/locale.cc +++ b/libstdc++-v3/src/c++98/locale.cc @@ -216,12 +216,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION #ifdef __GTHREADS if (__gthread_active_p()) __gthread_once(&_S_once, _S_initialize_once); - else #endif - { - if (!_S_c_locale) - _S_initialize_once(); - } + if (__builtin_expect (!_S_c_locale, 0)) + _S_initialize_once(); return _S_c_locale; } -- 2.35.3 ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2023-11-07 11:45 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <20231106115212.6DCC23858C00@sourceware.org> 2023-11-06 12:16 ` [PATCH] libstdc++/112351 - deal with __gthread_once failure during locale init Jakub Jelinek 2023-11-06 12:17 ` Jonathan Wakely [not found] <11125.123110606520900751@us-mta-255.us.mimecast.lan> 2023-11-06 12:15 ` Jonathan Wakely 2023-11-06 12:51 ` Richard Biener 2023-11-07 10:55 ` Richard Biener 2023-11-07 11:44 ` Jonathan Wakely 2023-11-06 11:52 Richard Biener
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