The testcase provided on BZ#19366 may update __nptl_nthreads in a wrong
order, triggering an early process exit because the thread decrement
the value twice.
The issue is once the thread exits without acting on cancellation,
it decreaments '__nptl_nthreads' and then atomically set
'cancelhandling' with EXITING_BIT (thus preventing further cancellation
handler to act). The issue happens if a SIGCANCEL is received between
checking '__ntpl_nthreads' and setting EXITING_BIT. To avoid it, the
'__nptl_nthreads' decrement is moved after EXITING_BIT.
It does fully follow the POSIX XSH 2.9.5 Thread Cancellation under
the heading Thread Cancellation Cleanup Handlers that states that
when a cancellation request is acted upon, or when a thread calls
pthread_exit(), the thread first disables cancellation by setting its
cancelability state to PTHREAD_CANCEL_DISABLE and its cancelability type
to PTHREAD_CANCEL_DEFERRED. The issue is '__pthread_enable_asynccancel'
explicit enabled assynchrnous cancellation, so an interrupted syscall
within the cancellation cleanup handlers might see an invalid cancelling
type (a possible fix might be possible with my proposed solution to
BZ#12683).
Trying to come up with a test is quite hard since it requires to
mimic the timing issue described below, however I see that the
bug report reproducer does not early exit anymore.
Checked on x86_64-linux-gnu.
It consolidates the tgkill call and it is the first step of making
pthread_cancel async-signal-safe. It also fix a possible issue
where the 'struct pthread' tid is not read atomically, which might
send an invalid cancellation signal (similar to what
db988e50a8 fixed for pthread_join).
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Now that pthread_kill is provided by libc.so it is possible to
implement the generic POSIX implementation as
'pthread_kill(pthread_self(), sig)'.
For Linux implementation, pthread_kill read the targeting TID from
the TCB. For raise, this it not possible because it would make raise
fail when issue after vfork (where creates the resulting process
has a different TID from the parent, but its TCB is not updated as
for pthread_create). To make raise use pthread_kill, it is make
usable from vfork by getting the target thread id through gettid
syscall.
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Now that the thread cancellation type is not accessed concurrently
anymore, it is possible to move it out the cancelhandling.
By removing the cancel state out of the internal thread cancel handling
state there is no need to check if cancelled bit was set in CAS
operation.
It allows simplifing the cancellation wrappers and the
CANCEL_CANCELED_AND_ASYNCHRONOUS is removed.
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Now that thread cancellation state is not accessed concurrently anymore,
it is possible to move it out the 'cancelhandling'.
The code is also simplified: CANCELLATION_P is replaced with a
internal pthread_testcancel call and the CANCELSTATE_BIT{MASK} is
removed.
With this behavior pthread_setcancelstate does not require to act on
cancellation if cancel type is asynchronous (is already handled either
by pthread_setcanceltype or by the signal handler).
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
The CANCELING_BITMASK is used as an optimization to avoid sending
the signal when pthread_cancel is called in a concurrent manner.
This requires then to put both the cancellation state and type on a
shared state (cancelhandling), since 'pthread_cancel' checks whether
cancellation is enabled and asynchrnous to either cancel itself of
sending the signal.
It also requires handle the CANCELING_BITMASK on
__pthread_disable_asynccancel, however this incurs in the same issues
described on BZ#12683: the cancellation is acted upon even *after*
syscall returns with user visible side-effects.
This patch removes this optimization and simplifies the pthread
cancellation implementation: pthread_cancel now first checks if
cancellation is already pending and if not always, sends a signal
if the target is not itself. The SIGCANCEL handler is also simpified
since there is not need to setup a CAS loop.
It also allows to move both the cancellation state and mode out of
'cancelhadling' (it is done in subsequent patches).
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Now that cancellation is not used anymore to handle thread setup
creation failure, the sighandle can be installed only when
pthread_cancel is actually used.
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
To setup either the thread scheduling parameters or affinity,
pthread_create enforce synchronization on created thread to wait until
its parent either release PD ownership or send a cancellation signal if
a failure occurs.
However, cancelling the thread does not deallocate the newly created
stack since cancellation expects that a pthread_join to deallocate any
allocated thread resouces (threads stack or TLS).
This patch changes on how the thread resource is deallocate in case of
failure to be synchronous, where the creating thread will signal the
created thread to exit early so it could be joined. The creating thread
will be reponsible for the resource cleanup before returning to the
caller.
To signal the creating thread that a failure has occured, an unused
'struct pthread' member, parent_cancelhandling_unsed, now indicates
whether the setup has failed so creating thread can proper exit.
This strategy also simplifies by not using thread cancellation and
thus not running libgcc_so load in the signal handler (which is
avoided in thread cancellation since 'pthread_cancel' is the one
responsible to dlopen libgcc_s). Another advantage is since the
early exit is move to first step at thread creation, the signal
mask is not already set and thus it can not act on change ID setxid
handler.
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
This commit removes the ELF constructor and internal variables from
dlfcn/dlfcn.c. The file now serves the same purpose as
nptl/libpthread-compat.c, so it is renamed to dlfcn/libdl-compat.c.
The use of libdl-shared-only-routines ensures that libdl.a is empty.
This commit adjusts the test suite not to use $(libdl). The libdl.so
symbolic link is no longer installed.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Some symbols have explicit versioned_symbol or compat_symbol markers
in the sources, but no corresponding entry in the Versions files.
This presently works because the local: * directive is only applied
to the base version.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
It checks whether an invalid affinity mask does return an error,
similar to what sysdeps/pthread/tst-bad-schedattr.c does for
pthread_attr_setschedparam.
Checked on x86_64-linux-gnu.
The 'create_thread' function is moved to pthread_create.c. It removes
the START_THREAD_DEFN and START_THREAD_SELF macros and make the
lock usage more clear (no need to cross-reference multiple files).
No functional change.
The signal is sent to all threads, some of which may have switched
to very small stacks. If they have also installed an alternate
signal stack, SA_ONSTACK makes this work. The Go runtime needs this:
runtime: C.setuid/C.setgid smashes Go stack
<https://github.com/golang/go/issues/9400>
Doing this for SIGCANCEL is less obviously beneficial and needs further
testing.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Since the variable expands to nothing under Linux, it is no longer
necessary to clutter the makefiles with it.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Only the placeholder compatibility symbols are left now.
The __errno_location symbol was removed (moved) using
scripts/move-symbol-to-libc.py.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbols were moved using scripts/move-symbol-to-libc.py.
The libpthread placeholder symbols need some changes because some
symbol versions have gone away completely. But
__errno_location@@GLIBC_2.0 still exists, so the GLIBC_2.0 version
is still there.
The internal __pthread_create symbol now points to the correct
function, so the sysdeps/nptl/thrd_create.c override is no longer
necessary.
There was an issue how the hidden alias of pthread_getattr_default_np
was defined, so this commit cleans up that aspects and removes the
GLIBC_PRIVATE export altogether.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
No abilist updates here because it is a GLIBC_PRIVATE symbol.
It's also necessary to move nptl_version into pthread_create, so
that it still ends up in static binaries.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Use the __nptl_tls_static_size_for_stack inline function instead,
and the GLRO (dl_tls_static_align) value directly.
The computation of GLRO (dl_tls_static_align) in
_dl_determine_tlsoffset ensures that the alignment is at least
TLS_TCB_ALIGN, which at least STACK_ALIGN (see allocate_stack).
Therefore, the additional rounding-up step is removed.
ALso move the initialization of the default stack size from
__pthread_initialize_minimal_internal to __pthread_early_init.
This introduces an extra system call during single-threaded startup,
but this simplifies the initialization sequence. No locking is
needed around the writes to __default_pthread_attr because the
process is single-threaded at this point.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Install signal handlers and unblock signals before pthread_create
creates the first thread.
create_thread in sysdeps/unix/sysv/linux/createthread.c can send
SIGCANCEL to the current thread, so the SIGCANCEL handler is currently
needed even if pthread_cancel is never called. (The way timer_create
uses SIGCANCEL does not need a signal handler; both SIG_DFL and SIG_IGN
dispositions should work.)
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbol was moved using scripts/move-symbol-to-libc.py.
The GLIBC_2.11 version is now empty, so add a placeholder symbol.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbol was moved using scripts/move-symbol-to-libc.py.
The GLIBC_2.3.4 version is now empty, so add a placeholder symbol.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbol was moved using scripts/move-symbol-to-libc.py.
Add __libpthread_version_placeholder@@GLIBC_2.12 for the targets
that need it.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbol was moved using scripts/move-symbol-to-libc.py.
__libpthread_version_placeholder@@GLIBC_2.2 is needed by this change;
the Versions entry for GLIBC_2.2 in libpthread had leftover symbols
due to an error in a previous conflict resolution. The condition
for the placeholder symbol is complicated because some architectures
have earlier symbols at the GLIBC_2.2 symbol versions, so the
placeholder is not required there (yet).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbol was moved using scripts/move-symbol-to-libc.py.
A new placeholder symbol __libpthread_version_placeholder@GLIBC_2.18
is needed to keep the GLIBC_2.18 symbol version in libpthread.
The __pthread_getattr_default_np@@GLIBC_PRIVATE export is used
from pthread_create.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
In libthread_db, use the exported GLIBC_PRIVATE symbols directly
instead of relying on _thread_db_* variables in libpthread
(which used to be created by the DB_FUNCTION macros).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The initialization of the report_events TCB field is now performed
in __tls_init_tp instead of __pthread_initialize_minimal_internal
(in libpthread).
The events interface is difficult to test because GDB stopped using it
in 2015. The td_thr_get_info change to ignore lookup issues is enough
to support GDB with this change.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This is similar to the fix for elf/tst-pldd (2f9046fb05):
it checks ptrace_scope value (values higher than 2 are too restrictive
to allow the test to run) and it rearranges the spawned processes
to make the target process the gdb child.
Checked on x86_64-linux-gnu with ptrace_scope set to 1.
The symbols were moved using scripts/move-symbol-to-libc.py,
in one commit due to their dependency on the internal
__concurrency_level variable.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbols were moved using scripts/move-symbol-to-libc.py.
Also clean up some unwinder linking leftover in the same spot
in nptl/pthreadP.h.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbol was moved using scripts/move-symbol-to-libc.py.
It is necessary to arrange for a
__libpthread_version_placeholder@GLIBC_2.6 on some of the powerpc
targets.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbols pthread_clockjoin_np, pthread_join, pthread_timedjoin_np,
pthread_tryjoin_np, thrd_join were moved using
scripts/move-symbol-to-libc.py.
Moving the symbols at the same time avoids the need for temporary
exports.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This replaces the FREE_P macro with the __nptl_stack_in_use inline
function. stack_list_del is renamed to __nptl_stack_list_del,
stack_list_add to __nptl_stack_list_add, __deallocate_stack to
__nptl_deallocate_stack, free_stacks to __nptl_free_stacks.
It is convenient to move __libpthread_freeres into libc at the
same time. This removes the temporary __default_pthread_attr_freeres
export and restores full freeres coverage for __default_pthread_attr.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbol was moved using scripts/move-symbol-to-libc.py.
The export of __default_pthread_attr_freeres is temporary. There
is a minor regression in freeres coverage because in the dynamic case,
__default_pthread_attr_freeres is no longer called if libpthread is
not linked in.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This removes the DEBUGGING_P macro and the __pthread_debug variable.
The __find_in_stack_list function is now unused and deleted as well.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The nptl version is used as default, since now with symbol always
present the single-thread optimization is tricky.
Hurd is not change, it is used it own lock scheme (which call
_cthreads_funlockfile).
Checked on x86_64-linux-gnu.
The nptl version is used as default, since now with symbol always
present the single-thread optimization is tricky.
Hurd is not change, it is used it own lock scheme (which call
_cthreads_ftrylockfile).
Checked on x86_64-linux-gnu.
The nptl version is used as default, since now with symbol always
present the single-thread optimization is tricky.
Hurd is not change, it is used it own lock scheme (which call
_cthreads_flockfile).
Checked on x86_64-linux-gnu.
The GLIBC_PRIVATE exports for these symbols are expected to be
temporary.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
stack_list_del overwrites the in-flight stack variable.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
All the stack lists are now in _rtld_global, so it is possible
to change stack permissions directly from there, instead of
calling into libpthread to do the change.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Only ia64 needs the page mask, and it is straightforward
to compute the value within the function itself.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Permissions of the cached stacks may have to be updated if an object
is loaded that requires executable stacks, so the dynamic loader
needs to know about these cached stacks.
The move of in_flight_stack and stack_cache_actsize is a requirement for
merging __reclaim_stacks into the fork implementation in libc.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
It is no longer needed after the SINGLE_THREADED_P consolidation.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This allows the elimination of the __libc_multiple_threads_ptr
variable in libpthread and its initialization procedure.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
If libpthread is included in libc, it is not necessary to delay
initialization of the lock/unlock function pointers until libpthread
is loaded. This eliminates two unprotected function pointers
from _rtld_global and removes some initialization code from
libpthread.
Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The symbol was moved using scripts/move-symbol-to-libc.py.
A small adjust to the sem_unlink implementation is necessary to avoid
a check-localplt failure.
A placeholder symbol to keep the GLIBC_2.1.1 version alive in
libpthread is added with this commit.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbols were moved using move-symbol-to-libc.py.
Both functions are moved at the same time because they depend
on internal functions in sysdeps/pthread/sem_routines.c, which
are moved in this commit as well. Additional hidden prototypes
are required to avoid check-localplt failures.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbol was moved using scripts/move-symbol-to-libc.py.
A new placeholder version is added at version GLIBC_2.30, to
preserve that version in libpthread.so.0.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Previously, the source file nptl/cancellation.c was compiled multiple
times, for libc, libpthread, librt. This commit switches to a single
implementation, with new __pthread_enable_asynccancel@@GLIBC_PRIVATE,
__pthread_disable_asynccancel@@GLIBC_PRIVATE exports.
The almost-unused CANCEL_ASYNC and CANCEL_RESET macros are replaced
by LIBC_CANCEL_ASYNC and LIBC_CANCEL_ASYNC macros. They call the
__pthread_* functions unconditionally now. The macros are still
needed because shared code uses them; Hurd has different definitions.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The symbol was moved using scripts/move-symbol-to-libc.py.
A temporary __pthread_testcancel@@GLIBC_PRIVATE export is created
because it is needed by the semaphore implementation.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The stack list is available in ld.so since commit
1daccf403b ("nptl: Move stack list
variables into _rtld_global"), so it's possible to walk the stack
list directly in ld.so and perform the initialization there.
This eliminates an unprotected function pointer from _rtld_global
and reduces the libpthread initialization code.
And deprecate it in <pthread.h>, redirecting it to sched_yield
for the time being.
The symbol was moved using scripts/move-symbol-to-libc.py.
No GLIBC_2.34 symbol version is added because of the compatibility
symbol status.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The symbol was moved using scripts/move-symbol-to-libc.py.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The symbol was moved using scripts/move-symbol-to-libc.py.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The symbol was moved using scripts/move-symbol-to-libc.py.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The symbol was moved using scripts/move-symbol-to-libc.py.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The symbol was moved using scripts/move-symbol-to-libc.py.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The symbol was moved using scripts/move-symbol-to-libc.py.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
And __pthread_rwlock_trywrlock as a compatibility symbol.
Remove the unused __libc_rwlock_trywrlock macro.
The symbols were moved using scripts/move-symbol-to-libc.py.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
And __pthread_rwlock_tryrdlock as a compatibility symbol.
Remove the unused __libc_rwlock_tryrdlock macro.
The symbols were moved using scripts/move-symbol-to-libc.py.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The symbol was moved using scripts/move-symbol-to-libc.py.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The symbol was moved using scripts/move-symbol-to-libc.py.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
And __pthread_rwlock_init as a compatibility symbol.
__libc_rwlock_init is changed to call __pthread_rwlock_init directly.
The symbols were moved using scripts/move-symbol-to-libc.py.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
And __pthread_rwlock_destroy as a compatibility symbol.
rwlocks do not need finalization, so change __libc_rwlock_fini to do
nothing.
The symbols were moved using scripts/move-symbol-to-libc.py.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
