The __libc_freeres framework does not extend to non-libc.so objects.
This causes problems in general for valgrind and mtrace detecting
unfreed objects in both libdl.so and libpthread.so. This change is
a pre-requisite to properly moving the malloc hooks out of malloc
since such a move now requires precise accounting of all allocated
data before destructors are run.
This commit adds a proper hook in libc.so.6 for both libdl.so and
for libpthread.so, this ensures that shm-directory.c which uses
freeit () to free memory is called properly. We also remove the
nptl_freeres hook and fall back to using weak-ref-and-check idiom
for a loaded libpthread.so, thus making this process similar for
all DSOs.
Lastly we follow best practice and use explicit free calls for
both libdl.so and libpthread.so instead of the generic hook process
which has undefined order.
Tested on x86_64 with no regressions.
Signed-off-by: DJ Delorie <dj@redhat.com>
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
On s390 (31bit) if glibc is build with -Os, pthread_join sometimes
blocks indefinitely. This is e.g. observable with
testcase intl/tst-gettext6.
pthread_join is calling lll_wait_tid(tid), which performs the futex-wait
syscall in a loop as long as tid != 0 (thread is alive).
On s390 (and build with -Os), tid is loaded from memory before
comparing against zero and then the tid is loaded a second time
in order to pass it to the futex-wait-syscall.
If the thread exits in between, then the futex-wait-syscall is
called with the value zero and it waits until a futex-wake occurs.
As the thread is already exited, there won't be a futex-wake.
In lll_wait_tid, the tid is stored to the local variable __tid,
which is then used as argument for the futex-wait-syscall.
But unfortunately the compiler is allowed to reload the value
from memory.
With this patch, the tid is loaded with atomic_load_acquire.
Then the compiler is not allowed to reload the value for __tid from memory.
ChangeLog:
[BZ #23137]
* sysdeps/nptl/lowlevellock.h (lll_wait_tid):
Use atomic_load_acquire to load __tid.
Prevent random runtime crashes due to missing symbols caused by mixed
libnss_* versions.
[BZ #22766]
* include/dlfcn.h [__libc_dl_open]: Replace RTLD_LAZY with RTLD_NOW.
* sysdeps/gnu/unwind-resume.c (__lib_gcc_s_init): Replace
__libc_dlopen_mode() using RTLD_NOW with __libc_dlopen.
* sysdeps/nptl/unwind-forcedunwind.c: Likewise.
Signed-off-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This patch filters out the internal NPTL signals (SIGCANCEL/SIGTIMER and
SIGSETXID) from signal functions. GLIBC on Linux requires both signals to
proper implement pthread cancellation, posix timers, and set*id posix
thread synchronization.
And not filtering out the internal signal is troublesome:
- A conformant program on a architecture that does not filter out the
signals might inadvertently disable pthread asynchronous cancellation,
set*id synchronization or posix timers.
- It might also to security issues if SIGSETXID is masked and set*id
functions are called (some threads might have effective user or group
id different from the rest).
The changes are basically:
- Change __is_internal_signal to bool and used on all signal function
that has a signal number as input. Also for signal function which accepts
signals sets (sigset_t) it assumes that canonical function were used to
add/remove signals which lead to some input simplification.
- Fix tst-sigset.c to avoid check for SIGCANCEL/SIGTIMER and SIGSETXID.
It is rewritten to check each signal indidually and to check realtime
signals using canonical macros.
- Add generic __clear_internal_signals and __is_internal_signal
version since both symbols are used on generic implementations.
- Remove superflous sysdeps/nptl/sigfillset.c.
- Remove superflous SIGTIMER handling on Linux __is_internal_signal
since it is the same of SIGCANCEL.
- Remove dangling define and obvious comment on nptl/sigaction.c.
Checked on x86_64-linux-gnu.
[BZ #22391]
* nptl/sigaction.c (__sigaction): Use __is_internal_signal to
check for internal nptl signals.
* nptl/sigaction.c (__sigaction): Likewise.
* signal/sigaddset.c (sigaddset): Likewise.
* signal/sigdelset.c (sigdelset): Likewise.
* sysdeps/posix/signal.c (__bsd_signal): Likewise.
* sysdeps/posix/sigset.c (sigset): Call and check sigaddset return
value.
* signal/sigfillset.c (sigfillset): User __clear_internal_signals
to filter out internal nptl signals.
* signal/tst-sigset.c (do_test): Check ech signal indidually and
also check realtime signals using standard macros.
* sysdeps/generic/internal-signals.h (__clear_internal_signals,
__is_internal_signal, __libc_signal_block_all,
__libc_signal_block_app, __libc_signal_restore_set): New functions.
* sysdeps/nptl/sigfillset.c: Remove file.
* sysdeps/unix/sysv/linux/internal-signals.h (__is_internal_signal):
Change return to bool.
(__clear_internal_signals): Remove SIGTIMER clean since it is
equal to SIGCANEL on Linux.
* sysdeps/unix/sysv/linux/sigtimedwait.c (__sigtimedwait): Assume
signal set was constructed using standard functions.
Reported-by: Yury Norov <ynorov@caviumnetworks.com>
This patch refactors the ARCH_FORK macro and the required architecture
specific header to simplify the required architecture definitions
to provide the fork syscall semantic and proper document current
Linux clone ABI variant.
Instead of require the reimplementation of arch-fork.h header, this
patch changes the ARCH_FORK to an inline function with clone ABI
defined by kernel-features.h define. The generic kernel ABI meant
for newer ports is used as default and redefine if the architecture
requires.
Checked on x86_64-linux-gnu and i686-linux-gnu. Also with a build
for all the afected ABIs.
* sysdeps/nptl/fork.c (ARCH_FORK): Replace by auch_fork.
* sysdeps/unix/sysv/linux/alpha/arch-fork.h: Remove file.
* sysdeps/unix/sysv/linux/riscv/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/aarch64/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/arm/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/hppa/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/i386/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/ia64/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/m68k/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/microblaze/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/mips/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/nios2/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/powerpc/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/s390/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/sh/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/sparc/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/tile/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/x86_64/arch-fork.h: Likewise.
* sysdeps/unix/sysv/linux/arch-fork.h (arch_fork): New function.
* sysdeps/unix/sysv/linux/aarch64/kernel-features.h: New file.
* sysdeps/unix/sysv/linux/riscv/kernel-features.h: Likewise.
* sysdeps/unix/sysv/linux/arm/kernel-features.h
(__ASSUME_CLONE_BACKWARDS): Define.
* sysdeps/unix/sysv/linux/createthread.c (ARCH_CLONE): Define to
__clone2 if __NR_clone2 is defined.
* sysdeps/unix/sysv/linux/hppa/kernel-features.h
(__ASSUME_CLONE_BACKWARDS): Likewise.
* sysdeps/unix/sysv/linux/i386/kernel-features.h
(__ASSUME_CLONE_BACKWARDS): Likewise.
* sysdeps/unix/sysv/linux/ia64/kernel-features.h
(__ASSUME_CLONE2): Likewise.
* sysdeps/unix/sysv/linux/microblaze/kernel-features.h
(__ASSUME_CLONE_BACKWARDS3): Likewise.
* sysdeps/unix/sysv/linux/kernel-features.h: Document possible clone
variants and the define architecture can use.
(__ASSUME_CLONE_DEFAULT): Define as default.
* sysdeps/unix/sysv/linux/mips/kernel-features.h
(__ASSUME_CLONE_BACKWARDS): Likewise.
* sysdeps/unix/sysv/linux/powerpc/kernel-features.h
(__ASSUME_CLONE_BACKWARDS): Likewise.
* sysdeps/unix/sysv/linux/s390/kernel-features.h
(__ASSUME_CLONE_BACKWARDS2): Likewise.
libpthread_nonshared.a is unused after this, so remove it from the
build.
There is no ABI impact because pthread_atfork was implemented using
__register_atfork in libc even before this change.
pthread_atfork has to be a weak alias because pthread_* names are not
reserved in libc.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* sysdeps/pthread/timer_routines.c: Include <timer_routines.h> instead
of <nptl/pthreadP.h>
(thread_attr_compare): Move function to...
* sysdeps/nptl/timer_routines.h: ... new header.
Current implementation (sysdeps/nptl/fork.c) replicates the atfork
handlers list backward to invoke the child handlers after fork/clone
syscall.
The internal atfork handlers is implemented as a single-linked list
so a lock-free algorithm can be used, trading fork mulithread call
performance for some code complexity and dynamic stack allocation
(since the backwards list should not fail).
This patch refactor it to use a dynarary instead of a linked list.
It simplifies the external variables need to be exported and also
the internal atfork handler member definition.
The downside is a serialization of fork call in multithread, since to
operate on the dynarray the internal lock should be used. However
as noted by Florian, it already acquires external locks for malloc
and libio so it is already hitting some lock contention. Besides,
posix_spawn should be faster and more scalable to run external programs
in multithread environments.
Checked on x86_64-linux-gnu.
* nptl/Makefile (routines): Remove unregister-atfork.
* nptl/register-atfork.c (fork_handler_pool): Remove variable.
(fork_handler_alloc): Remove function.
(fork_handlers, fork_handler_init): New variables.
(__fork_lock): Rename to atfork_lock.
(__register_atfork, __unregister_atfork, libc_freeres_fn): Rewrite
to use a dynamic array to add/remove atfork handlers.
* sysdeps/nptl/fork.c (__libc_fork): Likewise.
* sysdeps/nptl/fork.h (__fork_lock, __fork_handlers, __linkin_atfork):
Remove declaration.
(fork_handler): Remove next, refcntr, and need_signal member.
(__run_fork_handler_type): New enum.
(__run_fork_handlers): New prototype.
* sysdeps/nptl/libc-lockP.h (__libc_atfork): Remove declaration.
This patch renames the nptl-signals.h header to internal-signals.h.
On Linux the definitions and functions are not only NPTL related, but
used for other POSIX definitions as well (for instance SIGTIMER for
posix times, SIGSETXID for id functions, and signal block/restore
helpers) and since generic functions will be places and used in generic
implementation it makes more sense to decouple it from NPTL.
Checked on x86_64-linux-gnu.
* sysdeps/nptl/nptl-signals.h: Move to ...
* sysdeps/generic/internal-signals.h: ... here. Adjust internal
comments.
* sysdeps/unix/sysv/linux/internal-signals.h: Add include guards.
(__nptl_is_internal_signal): Rename to __is_internal_signal.
(__nptl_clear_internal_signals): Rename to __clear_internal_signals.
* sysdeps/unix/sysv/linux/raise.c: Adjust nptl-signal.h to
include-signals.h rename.
* nptl/pthreadP.h: Likewise.
* sysdeps/unix/sysv/linux/spawni.c (__spawni_child): Call
__is_internal_signal instead of __nptl_is_internal_signal.
This patch mechanically removes all remaining uses, and the
definitions, of the following libio name aliases:
name replaced with
---- -------------
_IO_FILE FILE
_IO_fpos_t __fpos_t
_IO_fpos64_t __fpos64_t
_IO_size_t size_t
_IO_ssize_t ssize_t or __ssize_t
_IO_off_t off_t
_IO_off64_t off64_t
_IO_pid_t pid_t
_IO_uid_t uid_t
_IO_wint_t wint_t
_IO_va_list va_list or __gnuc_va_list
_IO_BUFSIZ BUFSIZ
_IO_cookie_io_functions_t cookie_io_functions_t
__io_read_fn cookie_read_function_t
__io_write_fn cookie_write_function_t
__io_seek_fn cookie_seek_function_t
__io_close_fn cookie_close_function_t
I used __fpos_t and __fpos64_t instead of fpos_t and fpos64_t because
the definitions of fpos_t and fpos64_t depend on the largefile mode.
I used __ssize_t and __gnuc_va_list in a handful of headers where
namespace cleanliness might be relevant even though they're
internal-use-only. In all other cases, I used the public-namespace
name.
There are a tiny handful of places where I left a use of 'struct _IO_FILE'
alone, because it was being used together with 'struct _IO_FILE_plus'
or 'struct _IO_FILE_complete' in the same arithmetic expression.
Because this patch was almost entirely done with search and replace, I
may have introduced indentation botches. I did proofread the diff,
but I may have missed something.
The ChangeLog below calls out all of the places where this was not a
pure search-and-replace change.
Installed stripped libraries and executables are unchanged by this patch,
except that some assertions in vfscanf.c change line numbers.
* libio/libio.h (_IO_FILE): Delete; all uses changed to FILE.
(_IO_fpos_t): Delete; all uses changed to __fpos_t.
(_IO_fpos64_t): Delete; all uses changed to __fpos64_t.
(_IO_size_t): Delete; all uses changed to size_t.
(_IO_ssize_t): Delete; all uses changed to ssize_t or __ssize_t.
(_IO_off_t): Delete; all uses changed to off_t.
(_IO_off64_t): Delete; all uses changed to off64_t.
(_IO_pid_t): Delete; all uses changed to pid_t.
(_IO_uid_t): Delete; all uses changed to uid_t.
(_IO_wint_t): Delete; all uses changed to wint_t.
(_IO_va_list): Delete; all uses changed to va_list or __gnuc_va_list.
(_IO_BUFSIZ): Delete; all uses changed to BUFSIZ.
(_IO_cookie_io_functions_t): Delete; all uses changed to
cookie_io_functions_t.
(__io_read_fn): Delete; all uses changed to cookie_read_function_t.
(__io_write_fn): Delete; all uses changed to cookie_write_function_t.
(__io_seek_fn): Delete; all uses changed to cookie_seek_function_t.
(__io_close_fn): Delete: all uses changed to cookie_close_function_t.
* libio/iofopncook.c: Remove unnecessary forward declarations.
* libio/iolibio.h: Correct outdated commentary.
* malloc/malloc.c (__malloc_stats): Remove unnecessary casts.
* stdio-common/fxprintf.c (__fxprintf_nocancel):
Remove unnecessary casts.
* stdio-common/getline.c: Use _IO_getdelim directly.
Don't redefine ssize_t.
* stdio-common/printf_fp.c, stdio_common/printf_fphex.c
* stdio-common/printf_size.c: Don't redefine size_t or FILE.
Remove outdated comments.
* stdio-common/vfscanf.c: Don't redefine va_list.
In commit cba595c350 and commit
f81ddabffd, ABI compatibility with
applications was broken by increasing the size of the on-stack
allocated __pthread_unwind_buf_t beyond the oringal size.
Applications only have the origianl space available for
__pthread_unwind_register, and __pthread_unwind_next to use,
any increase in the size of __pthread_unwind_buf_t causes these
functions to write beyond the original structure into other
on-stack variables leading to segmentation faults in common
applications like vlc. The only workaround is to version those
functions which operate on the old sized objects, but this must
happen in glibc 2.28.
Thank you to Andrew Senkevich, H.J. Lu, and Aurelien Jarno, for
submitting reports and tracking the issue down.
The commit reverts the above mentioned commits and testing on
x86_64 shows that the ABI compatibility is restored. A tst-cleanup1
regression test linked with an older glibc now passes when run
with the newly built glibc. Previously a tst-cleanup1 linked with
an older glibc would segfault when run with an affected glibc build.
Tested on x86_64 with no regressions.
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
Disabling lazy binding reduces stack usage during unwinding.
Note that RTLD_NOW only makes a difference if libgcc.so has not
already been loaded, so this is only a partial fix.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
All binaries use TLS and thus need a properly set up TCB, so we can
simply return its address directly, instead of forwarding to the
libpthread implementation from libc.
For versioned symbols, the dynamic linker checks that the soname matches
the name supplied by the link editor, so a compatibility symbol in
libpthread is needed.
To avoid linking against the libpthread function in all cases, we would
have to bump the symbol version of libpthread in libc.so and supply a
compat symbol. This commit does not do that because the function
implementation is so small, so the overhead by two active copies of the
same function might well be smaller than the increase in symbol table
size.
On x86, padding in struct __jmp_buf_tag is used for shadow stack pointer
to support shadow stack in Intel Control-flow Enforcemen Technology.
Since the cancel_jmp_buf array is passed to setjmp and longjmp by
casting it to pointer to struct __jmp_buf_tag, it should be as large
as struct __jmp_buf_tag. Otherwise when shadow stack is enabled,
setjmp and longjmp will write and read beyond cancel_jmp_buf when saving
and restoring shadow stack pointer.
This patch adds bits/types/__cancel_jmp_buf_tag.h to define struct
__cancel_jmp_buf_tag so that Linux/x86 can add saved_mask to
cancel_jmp_buf.
Tested natively on i386, x86_64 and x32. Tested hppa-linux-gnu with
build-many-glibcs.py.
[BZ #22563]
* bits/types/__cancel_jmp_buf_tag.h: New file.
* sysdeps/unix/sysv/linux/x86/bits/types/__cancel_jmp_buf_tag.h
* sysdeps/unix/sysv/linux/x86/pthreaddef.h: Likewise.
* sysdeps/unix/sysv/linux/x86/nptl/pthreadP.h: Likewise.
* nptl/Makefile (headers): Add
bits/types/__cancel_jmp_buf_tag.h.
* nptl/descr.h [NEED_SAVED_MASK_IN_CANCEL_JMP_BUF]
(pthread_unwind_buf): Add saved_mask to cancel_jmp_buf.
* sysdeps/nptl/pthread.h: Include
<bits/types/__cancel_jmp_buf_tag.h>.
(__pthread_unwind_buf_t): Use struct __cancel_jmp_buf_tag with
__cancel_jmp_buf.
* sysdeps/unix/sysv/linux/hppa/pthread.h: Likewise.
This patch adds two new internal defines to set the internal
pthread_mutex_t layout required by the supported ABIS:
1. __PTHREAD_MUTEX_NUSERS_AFTER_KIND which control whether to define
__nusers fields before or after __kind. The preferred value for
is 0 for new ports and it sets __nusers before __kind.
2. __PTHREAD_MUTEX_USE_UNION which control whether internal __spins and
__list members will be place inside an union for linuxthreads
compatibility. The preferred value is 0 for ports and it sets
to not use an union to define both fields.
It fixes the wrong offsets value for __kind value on x86_64-linux-gnu-x32.
Checked with a make check run-built-tests=no on all afected ABIs.
[BZ #22298]
* nptl/allocatestack.c (allocate_stack): Check if
__PTHREAD_MUTEX_HAVE_PREV is non-zero, instead if
__PTHREAD_MUTEX_HAVE_PREV is defined.
* nptl/descr.h (pthread): Likewise.
* nptl/nptl-init.c (__pthread_initialize_minimal_internal):
Likewise.
* nptl/pthread_create.c (START_THREAD_DEFN): Likewise.
* sysdeps/nptl/fork.c (__libc_fork): Likewise.
* sysdeps/nptl/pthread.h (PTHREAD_MUTEX_INITIALIZER): Likewise.
* sysdeps/nptl/bits/thread-shared-types.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION): New
defines.
(__pthread_internal_list): Check __PTHREAD_MUTEX_USE_UNION instead
of __WORDSIZE for internal layout.
(__pthread_mutex_s): Check __PTHREAD_MUTEX_NUSERS_AFTER_KIND instead
of __WORDSIZE for internal __nusers layout and __PTHREAD_MUTEX_USE_UNION
instead of __WORDSIZE whether to use an union for __spins and __list
fields.
(__PTHREAD_MUTEX_HAVE_PREV): Define also for __PTHREAD_MUTEX_USE_UNION
case.
* sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION): New
defines.
* sysdeps/alpha/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/arm/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/hppa/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/ia64/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/m68k/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/mips/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/nios2/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/powerpc/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/s390/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/sh/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/sparc/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/tile/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
* sysdeps/x86/nptl/bits/pthreadtypes-arch.h
(__PTHREAD_MUTEX_NUSERS_AFTER_KIND, __PTHREAD_MUTEX_USE_UNION):
Likewise.
Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
glibc has an add-ons mechanism to allow additional software to be
integrated into the glibc build. Such add-ons may be within the glibc
source tree, or outside it at a path passed to the --enable-add-ons
configure option.
localedata and crypt were once add-ons, distributed in separate
release tarballs, but long since stopped using that mechanism.
Linuxthreads was always an add-on. Ports spent some time as an add-on
with separate release tarballs, then was first moved into the glibc
source tree, then had its sysdeps files moved into the main sysdeps
hierarchy so the add-ons mechanism was no longer used. NPTL spent
some time as an add-on in the main glibc tree before stopping using
the add-on mechanism. libidn used to have separate release tarballs
but no longer does so, but still uses the add-ons mechanism within the
glibc source tree. Various other software has supported building with
the add-ons mechanism at times in the past, but I don't think any is
still widely used.
Add-ons involve significant, little-used complexity in the glibc build
system, and make it hard to understand what the space of possible
glibc configurations is. This patch removes the add-ons mechanism.
libidn is now built via the Subdirs mechanism to cause any
configuration using sysdeps/unix/inet to build libidn; HAVE_LIBIDN
(which effectively means shared libraries are available) is now
defined via sysdeps/unix/inet/configure. Various references to
add-ons around the source tree are removed (in the case of maint.texi,
the example list of sysdeps directories is still very out of date).
Externally maintained ports should now put their files in the normal
sysdeps directory structure rather than being arranged as add-ons;
they probably need to change e.g. elf.h anyway, rather than actually
being able to work just as a drop-in subtree. Hurd libpthread should
be arranged similarly to NPTL, so some files might go in a
hurd-pthreads (or similar) top-level directory in glibc, while sysdeps
files should go in the normal sysdeps directory structure (possibly in
hurd or hurd-pthreads subdirectories, just as there are nptl
subdirectories in the sysdeps tree).
Tested for x86_64, and with build-many-glibcs.py.
* configure.ac (--enable-add-ons): Remove option.
(machine): Do not mention add-ons in comment.
(LIBC_PRECONFIGURE): Likewise.
(add_ons): Remove variable and sanity checks and logic to locate
add-ons.
(add_ons_automatic): Remove variable.
(configured_add_ons): Likewise.
(add_ons_sfx): Likewise.
(add_ons_pfx): Likewise.
(add_on_subdirs): Likewise.
(sysnames_add_ons): Likewise. Remove loop over add-ons and
consideration of add-ons in Implies handling.
(sysdeps_add_ons): Likewise.
* configure: Regenerated.
* libidn/configure.ac: Remove.
* libidn/configure: Likewise.
* sysdeps/unix/inet/configure.ac: New file.
* sysdeps/unix/inet/configure: New generated file.
* sysdeps/unix/inet/Subdirs: Add libidn.
* Makeconfig (sysdeps-srcdirs): Remove variable.
(+sysdep_dirs): Do not include $(sysdeps-srcdirs).
($(common-objpfx)config.status): Do not depend on add-on files.
($(common-objpfx)shlib-versions.v.i): Do not mention add-ons in
comment.
(all-subdirs): Do not include $(add-on-subdirs).
* Makefile (dist-prepare): Do not use $(sysdeps-add-ons).
* config.make.in (add-ons): Remove variable.
(add-on-subdirs): Likewise.
(sysdeps-add-ons): Likewise.
* manual/Makefile (add-chapters): Remove.
($(objpfx)texis): Do not depend on $(add-chapters).
(nonexamples): Do not handle $(add-chapters).
(examples): Do not handle $(add-ons).
(chapters.% top-menu.%): Do not pass '$(add-chapters)' to
libc-texinfo.sh.
* manual/install.texi (Installation): Do not mention add-ons.
(--enable-add-ons): Do not document configure option.
* INSTALL: Regenerated.
* manual/libc-texinfo.sh: Do not handle $2 add-ons argument.
* manual/maint.texi (Hierarchy Conventions): Do not mention
add-ons.
* scripts/build-many-glibcs.py (Glibc.build_glibc): Do not use
--enable-add-ons.
* scripts/gen-sorted.awk: Do not handle Subdirs files from
add-ons.
* scripts/test-installation.pl: Do not handle glibc-compat add-on.
* sysdeps/nptl/Makeconfig: Do not mention add-ons in comment.
This patch fixes some build issues when including types/sigevent_t.h
along with bits/pthreadtypes.h.
Checked on x86_64-linux-gnu and on a build on supported major ABIs.
[BZ #21715]
* sysdeps/nptl/bits/pthreadtypes.h (__have_pthread_attr_t): Fix typo
on definition.
_IO_MTSAFE_IO controls whether stdio is *built* with support for
multithreading. In the distant past it might also have worked as a
feature selection macro, allowing library *users* to select
thread-safe or lock-free stdio at application build time, I haven't
done the archaeology. Nowadays, defining _IO_MTSAFE_IO while using
the installed headers, or in _ISOMAC mode, will cause libio.h to throw
syntax errors.
This patch removes _IO_MTSAFE_IO from the public headers
(specifically, from libio/libio.h). The most important thing it
controlled in there was whether libio.h defines _IO_lock_t itself or
expects stdio-lock.h to have done it, and we do still need a
inter-header communication macro for that, because stdio-lock.h can
only define _IO_lock_t as a typedef. I've invented
_IO_lock_t_defined, which is defined by both versions of stdio-lock.h.
_IO_MTSAFE_IO also controlled the definitions of a handful of macros
that _might_ count as part of the public libio.h interface. They are
now unconditionally given their non-_IO_MTSAFE_IO definition in
libio/libio.h, and include/libio.h redefines them with the
_IO_MTSAFE_IO definition. This should minimize the odds of breaking
old software that actually uses those macros.
I suspect that this entire mechanism is vestigial, and that glibc
won't build anymore if you *don't* define _IO_MTSAFE_IO, but that's
another patchset. The bulk of libio.h is internal-use-only stuff that
no longer makes sense to expose (libstdc++ gave up on making a FILE
the same object as a C++ filebuf *decades* ago) but that, too, is
another patchset.
* libio/libio.h: Condition dummy definition of _IO_lock_t on
_IO_lock_t_defined, not _IO_MTSAFE_IO. Unconditionally use the
non-_IO_MTSAFE_IO definitions for _IO_peekc, _IO_flockfile,
_IO_funlockfile, and _IO_ftrylockfile. Only define
_IO_cleanup_region_start and _IO_cleanup_region_end if not
already defined.
* include/libio.h: If _IO_MTSAFE_IO is defined, redefine
_IO_peekc, _IO_flockfile, _IO_funlockfile, and _IO_ftrylockfile
appropriately.
* sysdeps/generic/stdio-lock.h, sysdeps/nptl/stdio-lock.h:
Define _IO_lock_t_defined after defining _IO_lock_t.
This patch removes all the replicated pthread definition accross the
architectures and consolidates it on shared headers. The new
organization is as follow:
* Architecture specific definition (such as pthread types sizes) are
place in the new pthreadtypes-arch.h header in arch specific path.
* All shared structure definition are moved to a common NPTL header
at sysdeps/nptl/bits/pthreadtypes.h (with now includes the arch
specific one for internal definitions).
* Also, for C11 future thread support, both mutex and condition
definition are placed in a common header at
sysdeps/nptl/bits/thread-shared-types.h.
It is also a refactor patch without expected functional changes.
Checked with a build for all major ABI (aarch64-linux-gnu, alpha-linux-gnu,
arm-linux-gnueabi, i386-linux-gnu, ia64-linux-gnu,
m68k-linux-gnu, microblaze-linux-gnu, mips{64}-linux-gnu, nios2-linux-gnu,
powerpc{64le}-linux-gnu, s390{x}-linux-gnu, sparc{64}-linux-gnu,
tile{pro,gx}-linux-gnu, and x86_64-linux-gnu).
* posix/Makefile (headers): Add pthreadtypes-arch.h and
thread-shared-types.h.
* sysdeps/aarch64/nptl/bits/pthreadtypes-arch.h: New file: arch
specific thread definition.
* sysdeps/alpha/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/arm/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/hppa/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/ia64/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/m68k/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/microblaze/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/mips/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/nios2/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/powerpc/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/s390/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/sh/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/sparc/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/tile/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/x86/nptl/bits/pthreadtypes-arch.h: Likewise.
* sysdeps/nptl/bits/thread-shared-types.h: New file: shared
thread definition between POSIX and C11.
* sysdeps/aarch64/nptl/bits/pthreadtypes.h.: Remove file.
* sysdeps/alpha/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/arm/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/hppa/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/m68k/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/microblaze/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/mips/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/nios2/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/ia64/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/powerpc/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/s390/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/sh/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/sparc/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/tile/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/x86/nptl/bits/pthreadtypes.h: Likewise.
* sysdeps/nptl/bits/pthreadtypes.h: New file: common thread
definitions shared across all architectures.
posix/wordexp-test.c used libc-internal.h for PTR_ALIGN_DOWN; similar
to what was done with libc-diag.h, I have split the definitions of
cast_to_integer, ALIGN_UP, ALIGN_DOWN, PTR_ALIGN_UP, and PTR_ALIGN_DOWN
to a new header, libc-pointer-arith.h.
It then occurred to me that the remaining declarations in libc-internal.h
are mostly to do with early initialization, and probably most of the
files including it, even in the core code, don't need it anymore. Indeed,
only 19 files actually need what remains of libc-internal.h. 23 others
need libc-diag.h instead, and 12 need libc-pointer-arith.h instead.
No file needs more than one of them, and 16 don't need any of them!
So, with this patch, libc-internal.h stops including libc-diag.h as
well as losing the pointer arithmetic macros, and all including files
are adjusted.
* include/libc-pointer-arith.h: New file. Define
cast_to_integer, ALIGN_UP, ALIGN_DOWN, PTR_ALIGN_UP, and
PTR_ALIGN_DOWN here.
* include/libc-internal.h: Definitions of above macros
moved from here. Don't include libc-diag.h anymore either.
* posix/wordexp-test.c: Include stdint.h and libc-pointer-arith.h.
Don't include libc-internal.h.
* debug/pcprofile.c, elf/dl-tunables.c, elf/soinit.c, io/openat.c
* io/openat64.c, misc/ptrace.c, nptl/pthread_clock_gettime.c
* nptl/pthread_clock_settime.c, nptl/pthread_cond_common.c
* string/strcoll_l.c, sysdeps/nacl/brk.c
* sysdeps/unix/clock_settime.c
* sysdeps/unix/sysv/linux/i386/get_clockfreq.c
* sysdeps/unix/sysv/linux/ia64/get_clockfreq.c
* sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c
* sysdeps/unix/sysv/linux/sparc/sparc64/get_clockfreq.c:
Don't include libc-internal.h.
* elf/get-dynamic-info.h, iconv/loop.c
* iconvdata/iso-2022-cn-ext.c, locale/weight.h, locale/weightwc.h
* misc/reboot.c, nis/nis_table.c, nptl_db/thread_dbP.h
* nscd/connections.c, resolv/res_send.c, soft-fp/fmadf4.c
* soft-fp/fmasf4.c, soft-fp/fmatf4.c, stdio-common/vfscanf.c
* sysdeps/ieee754/dbl-64/e_lgamma_r.c
* sysdeps/ieee754/dbl-64/k_rem_pio2.c
* sysdeps/ieee754/flt-32/e_lgammaf_r.c
* sysdeps/ieee754/flt-32/k_rem_pio2f.c
* sysdeps/ieee754/ldbl-128/k_tanl.c
* sysdeps/ieee754/ldbl-128ibm/k_tanl.c
* sysdeps/ieee754/ldbl-96/e_lgammal_r.c
* sysdeps/ieee754/ldbl-96/k_tanl.c, sysdeps/nptl/futex-internal.h:
Include libc-diag.h instead of libc-internal.h.
* elf/dl-load.c, elf/dl-reloc.c, locale/programs/locarchive.c
* nptl/nptl-init.c, string/strcspn.c, string/strspn.c
* malloc/malloc.c, sysdeps/i386/nptl/tls.h
* sysdeps/nacl/dl-map-segments.h, sysdeps/x86_64/atomic-machine.h
* sysdeps/unix/sysv/linux/spawni.c
* sysdeps/x86_64/nptl/tls.h:
Include libc-pointer-arith.h instead of libc-internal.h.
* elf/get-dynamic-info.h, sysdeps/nacl/dl-map-segments.h
* sysdeps/x86_64/atomic-machine.h:
Add multiple include guard.
The macros lll_trylock, lll_cond_trylock are extended by an __glibc_unlikely
hint. Now the trylock macros are based on the same assumption about a
free/busy lock as lll_lock.
With the hint gcc emits code in e.g. pthread_mutex_trylock which does
not use jumps if the lock is free. Without the hint it had to jump away
if the lock is free.
Tested on s390x, ppc.
ChangeLog:
* sysdeps/nptl/lowlevellock.h (lll_trylock, lll_cond_trylock):
Add __glibc_unlikely hint.
Robust mutexes acquired at the time of a call to fork() do not remain
acquired by the forked child process. We have to clear the list of
acquired robust mutexes before registering this list with the kernel;
otherwise, if some of the robust mutexes are process-shared, the parent
process can alter the child's robust mutex list, which can lead to
deadlocks or even modification of memory that may not be occupied by a
mutex anymore.
[BZ #19402]
* sysdeps/nptl/fork.c (__libc_fork): Clear list of acquired robust
mutexes.
lll_robust_unlock on i386 and x86_64 first sets the futex word to
FUTEX_WAITERS|0 before calling __lll_unlock_wake, which will set the
futex word to 0. If the thread is killed between these steps, then the
futex word will be FUTEX_WAITERS|0, and the kernel (at least current
upstream) will not set it to FUTEX_OWNER_DIED|FUTEX_WAITERS because 0 is
not equal to the TID of the crashed thread.
The lll_robust_lock assembly code on i386 and x86_64 is not prepared to
deal with this case because the fastpath tries to only CAS 0 to TID and
not FUTEX_WAITERS|0 to TID; the slowpath simply waits until it can CAS 0
to TID or the futex_word has the FUTEX_OWNER_DIED bit set.
This issue is fixed by removing the custom x86 assembly code and using
the generic C code instead. However, instead of adding more duplicate
code to the custom x86 lowlevellock.h, the code of the lll_robust* functions
is inlined into the single call sites that exist for each of these functions
in the pthread_mutex_* functions. The robust mutex paths in the latter
have been slightly reorganized to make them simpler.
This patch is meant to be easy to backport, so C11-style atomics are not
used.
[BZ #20985]
* nptl/Makefile: Adapt.
* nptl/pthread_mutex_cond_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove.
(LLL_ROBUST_MUTEX_LOCK_MODIFIER): New.
* nptl/pthread_mutex_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove.
(LLL_ROBUST_MUTEX_LOCK_MODIFIER): New.
(__pthread_mutex_lock_full): Inline lll_robust* functions and adapt.
* nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Inline
lll_robust* functions and adapt.
* nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise.
* sysdeps/nptl/lowlevellock.h (__lll_robust_lock_wait,
__lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait,
__lll_robust_timedlock, __lll_robust_unlock): Remove.
* sysdeps/unix/sysv/linux/i386/lowlevellock.h (lll_robust_lock,
lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove.
* sysdeps/unix/sysv/linux/x86_64/lowlevellock.h (lll_robust_lock,
lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove.
* sysdeps/unix/sysv/linux/sparc/lowlevellock.h (__lll_robust_lock_wait,
__lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait,
__lll_robust_timedlock, __lll_robust_unlock): Remove.
* nptl/lowlevelrobustlock.c: Remove file.
* nptl/lowlevelrobustlock.sym: Likewise.
* sysdeps/unix/sysv/linux/i386/lowlevelrobustlock.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/lowlevelrobustlock.S: Likewise.
This is a new implementation for condition variables, required
after http://austingroupbugs.net/view.php?id=609 to fix bug 13165. In
essence, we need to be stricter in which waiters a signal or broadcast
is required to wake up; this couldn't be solved using the old algorithm.
ISO C++ made a similar clarification, so this also fixes a bug in
current libstdc++, for example.
We can't use the old algorithm anymore because futexes do not guarantee
to wake in FIFO order. Thus, when we wake, we can't simply let any
waiter grab a signal, but we need to ensure that one of the waiters
happening before the signal is woken up. This is something the previous
algorithm violated (see bug 13165).
There's another issue specific to condvars: ABA issues on the underlying
futexes. Unlike mutexes that have just three states, or semaphores that
have no tokens or a limited number of them, the state of a condvar is
the *order* of the waiters. A waiter on a semaphore can grab a token
whenever one is available; a condvar waiter must only consume a signal
if it is eligible to do so as determined by the relative order of the
waiter and the signal.
Therefore, this new algorithm maintains two groups of waiters: Those
eligible to consume signals (G1), and those that have to wait until
previous waiters have consumed signals (G2). Once G1 is empty, G2
becomes the new G1. 64b counters are used to avoid ABA issues.
This condvar doesn't yet use a requeue optimization (ie, on a broadcast,
waking just one thread and requeueing all others on the futex of the
mutex supplied by the program). I don't think doing the requeue is
necessarily the right approach (but I haven't done real measurements
yet):
* If a program expects to wake many threads at the same time and make
that scalable, a condvar isn't great anyway because of how it requires
waiters to operate mutually exclusive (due to the mutex usage). Thus, a
thundering herd problem is a scalability problem with or without the
optimization. Using something like a semaphore might be more
appropriate in such a case.
* The scalability problem is actually at the mutex side; the condvar
could help (and it tries to with the requeue optimization), but it
should be the mutex who decides how that is done, and whether it is done
at all.
* Forcing all but one waiter into the kernel-side wait queue of the
mutex prevents/avoids the use of lock elision on the mutex. Thus, it
prevents the only cure against the underlying scalability problem
inherent to condvars.
* If condvars use short critical sections (ie, hold the mutex just to
check a binary flag or such), which they should do ideally, then forcing
all those waiter to proceed serially with kernel-based hand-off (ie,
futex ops in the mutex' contended state, via the futex wait queues) will
be less efficient than just letting a scalable mutex implementation take
care of it. Our current mutex impl doesn't employ spinning at all, but
if critical sections are short, spinning can be much better.
* Doing the requeue stuff requires all waiters to always drive the mutex
into the contended state. This leads to each waiter having to call
futex_wake after lock release, even if this wouldn't be necessary.
[BZ #13165]
* nptl/pthread_cond_broadcast.c (__pthread_cond_broadcast): Rewrite to
use new algorithm.
* nptl/pthread_cond_destroy.c (__pthread_cond_destroy): Likewise.
* nptl/pthread_cond_init.c (__pthread_cond_init): Likewise.
* nptl/pthread_cond_signal.c (__pthread_cond_signal): Likewise.
* nptl/pthread_cond_wait.c (__pthread_cond_wait): Likewise.
(__pthread_cond_timedwait): Move here from pthread_cond_timedwait.c.
(__condvar_confirm_wakeup, __condvar_cancel_waiting,
__condvar_cleanup_waiting, __condvar_dec_grefs,
__pthread_cond_wait_common): New.
(__condvar_cleanup): Remove.
* npt/pthread_condattr_getclock.c (pthread_condattr_getclock): Adapt.
* npt/pthread_condattr_setclock.c (pthread_condattr_setclock):
Likewise.
* npt/pthread_condattr_getpshared.c (pthread_condattr_getpshared):
Likewise.
* npt/pthread_condattr_init.c (pthread_condattr_init): Likewise.
* nptl/tst-cond1.c: Add comment.
* nptl/tst-cond20.c (do_test): Adapt.
* nptl/tst-cond22.c (do_test): Likewise.
* sysdeps/aarch64/nptl/bits/pthreadtypes.h (pthread_cond_t): Adapt
structure.
* sysdeps/arm/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/ia64/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/m68k/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/microblaze/nptl/bits/pthreadtypes.h (pthread_cond_t):
Likewise.
* sysdeps/mips/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/nios2/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/s390/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/sh/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/tile/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/unix/sysv/linux/alpha/bits/pthreadtypes.h (pthread_cond_t):
Likewise.
* sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h (pthread_cond_t):
Likewise.
* sysdeps/x86/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/nptl/internaltypes.h (COND_NWAITERS_SHIFT): Remove.
(COND_CLOCK_BITS): Adapt.
* sysdeps/nptl/pthread.h (PTHREAD_COND_INITIALIZER): Adapt.
* nptl/pthreadP.h (__PTHREAD_COND_CLOCK_MONOTONIC_MASK,
__PTHREAD_COND_SHARED_MASK): New.
* nptl/nptl-printers.py (CLOCK_IDS): Remove.
(ConditionVariablePrinter, ConditionVariableAttributesPrinter): Adapt.
* nptl/nptl_lock_constants.pysym: Adapt.
* nptl/test-cond-printers.py: Adapt.
* sysdeps/unix/sysv/linux/hppa/internaltypes.h (cond_compat_clear,
cond_compat_check_and_clear): Adapt.
* sysdeps/unix/sysv/linux/hppa/pthread_cond_timedwait.c: Remove file ...
* sysdeps/unix/sysv/linux/hppa/pthread_cond_wait.c
(__pthread_cond_timedwait): ... and move here.
* nptl/DESIGN-condvar.txt: Remove file.
* nptl/lowlevelcond.sym: Likewise.
* nptl/pthread_cond_timedwait.c: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_wait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_wait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_wait.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S: Likewise.
This patch remove the PID cache and usage in current GLIBC code. Current
usage is mainly used a performance optimization to avoid the syscall,
however it adds some issues:
- The exposed clone syscall will try to set pid/tid to make the new
thread somewhat compatible with current GLIBC assumptions. This cause
a set of issue with new workloads and usecases (such as BZ#17214 and
[1]) as well for new internal usage of clone to optimize other algorithms
(such as clone plus CLONE_VM for posix_spawn, BZ#19957).
- The caching complexity also added some bugs in the past [2] [3] and
requires more effort of each port to handle such requirements (for
both clone and vfork implementation).
- Caching performance gain in mainly on getpid and some specific
code paths. The getpid performance leverage is questionable [4],
either by the idea of getpid being a hotspot as for the getpid
implementation itself (if it is indeed a justifiable hotspot a
vDSO symbol could let to a much more simpler solution).
Other usage is mainly for non usual code paths, such as pthread
cancellation signal and handling.
For thread creation (on stack allocation) the code simplification in fact
adds some performance gain due the no need of transverse the stack cache
and invalidate each element pid.
Other thread usages will require a direct getpid syscall, such as
cancellation/setxid signal, thread cancellation, thread fail path (at
create_thread), and thread signal (pthread_kill and pthread_sigqueue).
However these are hardly usual hotspots and I think adding a syscall is
justifiable.
It also simplifies both the clone and vfork arch-specific implementation.
And by review each fork implementation there are some discrepancies that
this patch also solves:
- microblaze clone/vfork does not set/reset the pid/tid field
- hppa uses the default vfork implementation that fallback to fork.
Since vfork is deprecated I do not think we should bother with it.
The patch also removes the TID caching in clone. My understanding for
such semantic is try provide some pthread usage after a user program
issue clone directly (as done by thread creation with CLONE_PARENT_SETTID
and pthread tid member). However, as stated before in multiple discussions
threads, GLIBC provides clone syscalls without further supporting all this
semantics.
I ran a full make check on x86_64, x32, i686, armhf, aarch64, and powerpc64le.
For sparc32, sparc64, and mips I ran the basic fork and vfork tests from
posix/ folder (on a qemu system). So it would require further testing
on alpha, hppa, ia64, m68k, nios2, s390, sh, and tile (I excluded microblaze
because it is already implementing the patch semantic regarding clone/vfork).
[1] https://codereview.chromium.org/800183004/
[2] https://sourceware.org/ml/libc-alpha/2006-07/msg00123.html
[3] https://sourceware.org/bugzilla/show_bug.cgi?id=15368
[4] http://yarchive.net/comp/linux/getpid_caching.html
* sysdeps/nptl/fork.c (__libc_fork): Remove pid cache setting.
* nptl/allocatestack.c (allocate_stack): Likewise.
(__reclaim_stacks): Likewise.
(setxid_signal_thread): Obtain pid through syscall.
* nptl/nptl-init.c (sigcancel_handler): Likewise.
(sighandle_setxid): Likewise.
* nptl/pthread_cancel.c (pthread_cancel): Likewise.
* sysdeps/unix/sysv/linux/pthread_kill.c (__pthread_kill): Likewise.
* sysdeps/unix/sysv/linux/pthread_sigqueue.c (pthread_sigqueue):
Likewise.
* sysdeps/unix/sysv/linux/createthread.c (create_thread): Likewise.
* sysdeps/unix/sysv/linux/getpid.c: Remove file.
* nptl/descr.h (struct pthread): Change comment about pid value.
* nptl/pthread_getattr_np.c (pthread_getattr_np): Remove thread
pid assert.
* sysdeps/unix/sysv/linux/pthread-pids.h (__pthread_initialize_pids):
Do not set pid value.
* nptl_db/td_ta_thr_iter.c (iterate_thread_list): Remove thread
pid cache check.
* nptl_db/td_thr_validate.c (td_thr_validate): Likewise.
* sysdeps/aarch64/nptl/tcb-offsets.sym: Remove pid offset.
* sysdeps/alpha/nptl/tcb-offsets.sym: Likewise.
* sysdeps/arm/nptl/tcb-offsets.sym: Likewise.
* sysdeps/hppa/nptl/tcb-offsets.sym: Likewise.
* sysdeps/i386/nptl/tcb-offsets.sym: Likewise.
* sysdeps/ia64/nptl/tcb-offsets.sym: Likewise.
* sysdeps/m68k/nptl/tcb-offsets.sym: Likewise.
* sysdeps/microblaze/nptl/tcb-offsets.sym: Likewise.
* sysdeps/mips/nptl/tcb-offsets.sym: Likewise.
* sysdeps/nios2/nptl/tcb-offsets.sym: Likewise.
* sysdeps/powerpc/nptl/tcb-offsets.sym: Likewise.
* sysdeps/s390/nptl/tcb-offsets.sym: Likewise.
* sysdeps/sh/nptl/tcb-offsets.sym: Likewise.
* sysdeps/sparc/nptl/tcb-offsets.sym: Likewise.
* sysdeps/tile/nptl/tcb-offsets.sym: Likewise.
* sysdeps/x86_64/nptl/tcb-offsets.sym: Likewise.
* sysdeps/unix/sysv/linux/aarch64/clone.S: Remove pid and tid caching.
* sysdeps/unix/sysv/linux/alpha/clone.S: Likewise.
* sysdeps/unix/sysv/linux/arm/clone.S: Likewise.
* sysdeps/unix/sysv/linux/hppa/clone.S: Likewise.
* sysdeps/unix/sysv/linux/i386/clone.S: Likewise.
* sysdeps/unix/sysv/linux/ia64/clone2.S: Likewise.
* sysdeps/unix/sysv/linux/mips/clone.S: Likewise.
* sysdeps/unix/sysv/linux/nios2/clone.S: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/clone.S: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/clone.S: Likewise.
* sysdeps/unix/sysv/linux/sh/clone.S: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/clone.S: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/clone.S: Likewise.
* sysdeps/unix/sysv/linux/tile/clone.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/clone.S: Likewise.
* sysdeps/unix/sysv/linux/aarch64/vfork.S: Remove pid set and reset.
* sysdeps/unix/sysv/linux/alpha/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/arm/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/i386/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/ia64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/m68k/clone.S: Likewise.
* sysdeps/unix/sysv/linux/m68k/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/mips/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/nios2/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/sh/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/tile/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/tst-clone2.c (f): Remove direct pthread
struct access.
(clone_test): Remove function.
(do_test): Rewrite to take in consideration pid is not cached anymore.
Many headers are expected to expose a subset of the type definitions
in time.h. time.h has a whole bunch of messy logic for conditionally
defining some its types and structs, but, as best I can tell, this
has never worked 100%. In particular, __need_timespec is ineffective
if _TIME_H has already been defined, which means that if you compile
#include <time.h>
#include <sched.h>
with e.g. -fsyntax-only -std=c89 -Wall -Wsystem-headers, you will get
In file included from test.c:2:0:
/usr/include/sched.h:74:57: warning: "struct timespec" declared inside
parameter list will not be visible outside of this definition or declaration
extern int sched_rr_get_interval (__pid_t __pid, struct timespec *__t) __THROW;
^~~~~~~~
And if you want to _use_ sched_rr_get_interval in a TU compiled that
way, you're hosed.
This patch replaces all of that with small bits/types/TYPE.h headers
as introduced earlier. time.h and bits/time.h are now *much* simpler,
and a lot of other headers are slightly simpler.
* time/time.h, bits/time.h, sysdeps/unix/sysv/linux/bits/time.h:
Remove all logic conditional on __need macros. Move all the
conditionally defined types to their own headers...
* time/bits/types/clock_t.h: Define clock_t here.
* time/bits/types/clockid_t.h: Define clockid_t here.
* time/bits/types/struct_itimerspec.h: Define struct itimerspec here.
* time/bits/types/struct_timespec.h: Define struct timespec here.
* time/bits/types/struct_timeval.h: Define struct timeval here.
* time/bits/types/struct_tm.h: Define struct tm here.
* time/bits/types/time_t.h: Define time_t here.
* time/bits/types/timer_t.h: Define timer_t here.
* time/Makefile: Install the new headers.
* bits/resource.h, io/fcntl.h, io/sys/poll.h, io/sys/stat.h
* io/utime.h, misc/sys/select.h, posix/sched.h, posix/sys/times.h
* posix/sys/types.h, resolv/netdb.h, rt/aio.h, rt/mqueue.h
* signal/signal.h, pthread/semaphore.h, sysdeps/nptl/pthread.h
* sysdeps/unix/sysv/linux/alpha/bits/resource.h
* sysdeps/unix/sysv/linux/alpha/sys/acct.h
* sysdeps/unix/sysv/linux/bits/resource.h
* sysdeps/unix/sysv/linux/bits/timex.h
* sysdeps/unix/sysv/linux/mips/bits/resource.h
* sysdeps/unix/sysv/linux/net/ppp_defs.h
* sysdeps/unix/sysv/linux/sparc/bits/resource.h
* sysdeps/unix/sysv/linux/sys/acct.h
* sysdeps/unix/sysv/linux/sys/timerfd.h
* sysvipc/sys/msg.h, sysvipc/sys/sem.h, sysvipc/sys/shm.h
* time/sys/time.h, time/sys/timeb.h
Use the new bits/types headers.
* include/time.h: Remove __need logic.
* include/bits/time.h
* include/bits/types/clock_t.h, include/bits/types/clockid_t.h
* include/bits/types/time_t.h, include/bits/types/timer_t.h
* include/bits/types/struct_itimerspec.h
* include/bits/types/struct_timespec.h
* include/bits/types/struct_timeval.h
* include/bits/types/struct_tm.h:
New wrapper headers.
Nothing depends on the PTW macro anymore, so the mechanism to define
PTW for recompliations of libc routines is no longer needed. The
source files are still recompiled for the nptl directory, just without
the “ptw-” prefix.
(Reducing the number of pattern rules in sysd-rules is critical for
improving make performance.)
Existing interposed mallocs do not define the glibc-internal
fork callbacks (and they should not), so statically interposed
mallocs lead to link failures because the strong reference from
fork pulls in glibc's malloc, resulting in multiple definitions
of malloc-related symbols.
This provides a band-aid and addresses the scenario where fork is
called from a signal handler while the process is in the malloc
subsystem (or has acquired the libio list lock). It does not
address the general issue of async-signal-safety of fork;
multi-threaded processes are not covered, and some glibc
subsystems have fork handlers which are not async-signal-safe.
Previously, a thread M invoking fork would acquire locks in this order:
(M1) malloc arena locks (in the registered fork handler)
(M2) libio list lock
A thread F invoking flush (NULL) would acquire locks in this order:
(F1) libio list lock
(F2) individual _IO_FILE locks
A thread G running getdelim would use this order:
(G1) _IO_FILE lock
(G2) malloc arena lock
After executing (M1), (F1), (G1), none of the threads can make progress.
This commit changes the fork lock order to:
(M'1) libio list lock
(M'2) malloc arena locks
It explicitly encodes the lock order in the implementations of fork,
and does not rely on the registration order, thus avoiding the deadlock.
The previous barrier implementation did not fulfill the POSIX requirements
for when a barrier can be destroyed. Specifically, it was possible that
threads that haven't noticed yet that their round is complete still access
the barrier's memory, and that those accesses can happen after the barrier
has been legally destroyed.
The new algorithm does not have this issue, and it avoids using a lock
internally.
POSIX and C++11 require that a thread can destroy a mutex if no other
thread owns the mutex, is blocked on the mutex, or will try to acquire
it in the future. After destroying the mutex, it can reuse or unmap the
underlying memory. Thus, we must not access a mutex' memory after
releasing it. Currently, we can load the private flag after releasing
the mutex, which is fixed by this patch.
See https://sourceware.org/bugzilla/show_bug.cgi?id=13690 for more
background.
We need to call futex_wake on the lock after releasing it, however. This
is by design, and can lead to spurious wake-ups on unrelated futex words
(e.g., when the mutex memory is reused for another mutex). This behavior
is documented in the glibc-internal futex API and in recent drafts of the
Linux kernel's futex documentation (see the draft_futex branch of
git://git.kernel.org/pub/scm/docs/man-pages/man-pages.git).
sysdeps/nptl/configure.ac tests for forced unwind support and the C
cleanup attribute, giving errors if either is unsupported. It does
nothing beyond running those two tests.
Both the attribute, and _Unwind_GetCFA which is used in the forced
unwind test, were added in GCC 3.3. Thus these tests are long
obsolete, and this patch removes the configure fragment running them,
along with associated conditionals.
Tested for x86_64 and x86 (testsuite, and that installed stripped
shared libraries are unchanged by the patch).
* sysdeps/nptl/configure.ac: Remove file.
* sysdeps/nptl/configure: Remove generated file.
* configure.ac (libc_cv_forced_unwind): Do not substitute.
* configure: Regenerated.
* config.h.in (HAVE_FORCED_UNWIND): Remove #undef.
* config.make.in (have-forced-unwind): Remove variable.
* nptl/Makefile [$(have-forced-unwind) = yes]: Make code
unconditional.
* nptl/descr.h [HAVE_FORCED_UNWIND]: Likewise.
* nptl/unwind.c [HAVE_FORCED_UNWIND]: Likewise.
(__pthread_unwind) [!HAVE_FORCED_UNWIND]: Remove conditional code.
* nptl/version.c [HAVE_FORCED_UNWIND]: Make code unconditional.
* sysdeps/nptl/Makefile [$(have-forced-unwind) = yes]: Make code
unconditional.
sysdeps/nptl/configure.ac has code to give errors if certain tests in
the top-level configure failed. However, all those failure conditions
also produce errors in the top-level configure, so the errors in the
NPTL configure are completely redundant; this patch removes them.
(As suggested in
<https://sourceware.org/ml/libc-alpha/2015-10/msg00510.html>, I think
the top-level tests in question can be completely removed as
unnecessary given the version tests. But even without that there is
clearly no point in duplicating code that gives an error if the test
fails.)
Tested for x86_64 (testsuite, and that installed shared libraries are
unchanged by the patch).
* sysdeps/nptl/configure.ac: Do not give errors based on the
results of top-level configure tests.
* sysdeps/nptl/configure: Regenerated.
It was noted in
<https://sourceware.org/ml/libc-alpha/2012-09/msg00305.html> that the
bits/*.h naming scheme should only be used for installed headers.
This patch renames bits/stdio-lock.h to plain stdio-lock.h to follow
that convention.
Tested for x86_64 (testsuite, and that installed stripped shared
libraries are unchanged by the patch).
[BZ #14912]
* bits/stdio-lock.h: Move to ...
* sysdeps/generic/stdio-lock.h: ...here.
(_BITS_STDIO_LOCK_H): Rename macro to _STDIO_LOCK_H.
* sysdeps/nptl/bits/stdio-lock.h: Move to ...
* sysdeps/nptl/stdio-lock.h: ...here.
(_BITS_STDIO_LOCK_H): Rename macro to _STDIO_LOCK_H.
* include/libio.h: Include <stdio-lock.h> instead of
<bits/stdio-lock.h>.
* sysdeps/nptl/fork.c: Likewise.
* sysdeps/pthread/flockfile.c: Likewise.
* sysdeps/pthread/ftrylockfile.c: Likewise.
* sysdeps/pthread/funlockfile.c: Likewise.
