This no longer seems useful. Remove it.
This was prompted by a "cast discards volatile qualifier" warning
in libthr when WARNS=6.
Reviewed by: kib
MFC after: 3 days
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D10832
This was prompted by a compiler warning about 'ret' shadowing
a local variable in the callers of the macro.
Reviewed by: kib
MFC after: 3 days
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D10832
Fix warnings about the following when WARNS=6 (which I will commit soon):
- casting away const
- no previous 'extern' declaration for non-static variable
- others as explained by #pragmas and comments
- unused parameters
The last is the only functional change.
Reviewed by: kib
MFC after: 3 days
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D10808
Add a clock_nanosleep() syscall, as specified by POSIX.
Make nanosleep() a wrapper around it.
Attach the clock_nanosleep test from NetBSD. Adjust it for the
FreeBSD behavior of updating rmtp only when interrupted by a signal.
I believe this to be POSIX-compliant, since POSIX mentions the rmtp
parameter only in the paragraph about EINTR. This is also what
Linux does. (NetBSD updates rmtp unconditionally.)
Copy the whole nanosleep.2 man page from NetBSD because it is complete
and closely resembles the POSIX description. Edit, polish, and reword it
a bit, being sure to keep any relevant text from the FreeBSD page.
Reviewed by: kib, ngie, jilles
MFC after: 3 weeks
Relnotes: yes
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D10020
Replace uses of the GCC __nonnull__ attribute with the clang nullability
qualifiers. The replacement should be transparent for clang developers as
the new qualifiers will produce the same warnings and will be useful for
static checkers but will not cause aggressive optimizations.
GCC will not produce such warnings and developers will have to use
upgraded GCC ports built with the system headers from r312538.
Hinted by: Apple's Libc-1158.20.4, Bionic libc
MFC after: 11.1 Release
Differential Revision: https://reviews.freebsd.org/D9004
Leave robust-protected region before checking for cancellation by
calling _thr_testcancel(). Otherwise, if cancelling request was
pending, the cancel handler is called with the dandling inact_mtx,
which triggers an assert if any mutex operation is performed by the
handler.
Reported and tested by: Dimitri Staessens <dimitri.staessens@intec.ugent.be>
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
This is the backing feature to implement C++11 thread storage duration
specified by the thread_local keyword. A destructor for given
thread-local object is registered to be executed at the thread
termination time using __cxa_thread_atexit(). Libc calls the
__cxa_thread_calls_dtors() during exit(3), before finalizers and
atexit functions, and libthr calls the function at the thread
termination time, after the stack unwinding and thread-specific key
destruction.
There are several uncertainties in the API which lacks a formal
specification. Among them:
- is it allowed to register destructors during destructing;
we allow, but limiting the nesting level. If too many iterations
detected, a diagnostic is issued to stderr and thread forcibly
terminates for now.
- how to handle destructors which belong to an unloading dso;
for now, we ignore destructor calls for such entries, and
issue a diagnostic. Linux does prevent dso unload until all
threads with destructors from the dso terminated.
It is supposed that the diagnostics allow to detect real-world
applications relying on the above details and possibly adjust
our implementation. Right now the choices were to provide the slim
API (but that rarely stands the practice test).
Tests are added to check generic functionality and to specify some of
the above implementation choices.
Submitted by: Mahdi Mokhtari <mokhi64_gmail.com>
Reviewed by: theraven
Discussed with: dim (detection of -std=c++11 supoort for tests)
Sponsored by: The FreeBSD Foundation (my involvement)
MFC after: 2 weeks
Differential revisions: https://reviews.freebsd.org/D7224,
https://reviews.freebsd.org/D7427
the return value, in particular console-kit-daemon.
Reported by: Ivan Klymenko <fidaj@ukr.net>
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Approved by: re (gjb)
adaptive mutex, return EDEADLK as required by POSIX. The
pthread_mutex_lock() is already compliant.
Tested by: Guy Yur <guyyur@gmail.com>
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Approved by: re (gjb)
No functional change, although _thread_printf() may be slightly less functional
or render some values differently from libc snprintf(3). No ABI change.
Reviewed by: kib
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D6672
This avoids unneccessary casts and make the calls to _thr_ucond_*()
functions less questionable.
The c_spare field was not included into struct pthread_cond, so the
change modifies libthr ABI for shared condvars. But since an off-page
does not legitimately contains any other data past the struct
pthread_cond, the change keeps shared condvars from pre- and post-
changed libthr compatible. Also note that the whole struct ucond was
never copied in or out by kernel.
For private condvars, the privately allocated memory was never exposed
outside libthr.
Sponsored by: The FreeBSD Foundation
intention of the POSIX IEEE Std 1003.1TM-2008/Cor 1-2013.
A robust mutex is guaranteed to be cleared by the system upon either
thread or process owner termination while the mutex is held. The next
mutex locker is then notified about inconsistent mutex state and can
execute (or abandon) corrective actions.
The patch mostly consists of small changes here and there, adding
neccessary checks for the inconsistent and abandoned conditions into
existing paths. Additionally, the thread exit handler was extended to
iterate over the userspace-maintained list of owned robust mutexes,
unlocking and marking as terminated each of them.
The list of owned robust mutexes cannot be maintained atomically
synchronous with the mutex lock state (it is possible in kernel, but
is too expensive). Instead, for the duration of lock or unlock
operation, the current mutex is remembered in a special slot that is
also checked by the kernel at thread termination.
Kernel must be aware about the per-thread location of the heads of
robust mutex lists and the current active mutex slot. When a thread
touches a robust mutex for the first time, a new umtx op syscall is
issued which informs about location of lists heads.
The umtx sleep queues for PP and PI mutexes are split between
non-robust and robust.
Somewhat unrelated changes in the patch:
1. Style.
2. The fix for proper tdfind() call use in umtxq_sleep_pi() for shared
pi mutexes.
3. Removal of the userspace struct pthread_mutex m_owner field.
4. The sysctl kern.ipc.umtx_vnode_persistent is added, which controls
the lifetime of the shared mutex associated with a vnode' page.
Reviewed by: jilles (previous version, supposedly the objection was fixed)
Discussed with: brooks, Martin Simmons <martin@lispworks.com> (some aspects)
Tested by: pho
Sponsored by: The FreeBSD Foundation
cycle. The flag currently is cleared by the resumed thread. If next
suspend request comes before the thread was able to clean the flag, in
which case suspender skip the thread.
Instead, clear the THR_FLAGS_SUSPEND flag in resume_common(), we do
not care how much code was executed in the resumed thread when the
pthread_resume_*np(s) functions returned.
PR: 209233
Reported by: Lawrence Esswood <le277@cam.ac.uk>
MFC after: 1 week
is safe to call pthread_mutex_init() on the same shared mutex several
times. POSIX claims that the behaviour in this case is undefined.
Make this working by only allowing one caller to initialize the mutex.
Other callers either see already completed initialization and do
nothing, or busy-loop yielding while designated initializer finishes.
Also make the API requirements loose by initializing mutexes on other
pthread_mutex*() calls if they see uninitialized shared mutex.
Only mutexes provide the hack for now, but it could be also
implemented for other process shared primitives from libthr.
Reported and tested by: "Oleg V. Nauman" <oleg@opentransfer.com>
Sponsored by: The FreeBSD Foundation
of the pshared hash in child is consistent and can be safely used.
Reported and tested by: "Oleg V. Nauman" <oleg@opentransfer.com>
Sponsored by: The FreeBSD Foundation
control terminal, activated when running with pid 1. It is
application duty to handle this, and unsuspecting init replacements
which are linked with libthr would be broken by this.
The pre-resolving of getpid() is restored, just in case.
Reviewed by: jilles
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
breaking the ABI. Special value is stored in the lock pointer to
indicate shared lock, and offline page in the shared memory is
allocated to store the actual lock.
Reviewed by: vangyzen (previous version)
Discussed with: deischen, emaste, jhb, rwatson,
Martin Simmons <martin@lispworks.com>
Tested by: pho
Sponsored by: The FreeBSD Foundation
do not participate in the global symbols namespace, but rtld locks are
still replaced and functions are interposed. In particular,
__pthread_map_stacks_exec is resolved to the libc version. If a
library is loaded later, which requires adjustment of the stack
protection mode, rtld calls into libc __pthread_map_stacks_exec due to
the symbols scope. The libc version might recurse into binder and
recursively acquire rtld bind lock, causing the hang.
Make libc __pthread_map_stacks_exec() interposed, which synchronizes
rtld locks and version of the stack exec hook when libthr loaded,
regardless of the symbol scope control or symbol resolution order.
The __pthread_map_stacks_exec() symbol is removed from the private
version in libthr since libc symbol now operates correctly in presence
of libthr.
Reported and tested by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
calling thread is supposed to see accesses issued by the initializer.
This means that the read of the once_control->state variable should
have an acquire semantic. Use atomic_thread_fence_acq() when the
value read is ONCE_DONE, instead of straightforward atomic_load_acq(),
to only put a barrier when needed (*).
On the other hand, the updates of the once_control->state with the
intermediate progress state do not need to synchronize with other
state accesses, remove _acq suffix.
Reviewed by: alc (previous version)
Suggested by: alc (*)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
avoids recursion into rtld when leaving libthr critical section for
the deferred signal delivery.
For the same reason, use syscall(2) instead of referencing
__sys_sigreturn(2). Syscall() is already pre-resolved for fork()
interceptor.
Tested by: Andre Meiser <ortadur@web.de>
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
to handle per-thread information. Since our pthread_setspecific()
implementation calls calloc(3) to allocate per-thread specific data
storage, things get complicated.
Switch the allocator to use bare mmap(2). There is some loss of the
allocated page, since e.g. on amd64, PTHREAD_KEYS_MAX * sizeof(struct
pthread_specific_elem) is 3K (it actually spans whole page due to
padding), but I believe it is more acceptable than additional code for
specialized allocator().
The alternatives would either to make the specific data array be part of
the struct thread, or use internal bindings to call the libc malloc,
avoiding interposing.
Also do the style pass over the thr_spec.c, esp. simplify the
conditionals nesting by returning early when an error detected.
Remove trivial comments.
Found by: yuri@rawbw.com
PR: 200138
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
pwrite(2) syscalls are wrapped to provide compatibility with pre-7.x
kernels which required padding before the off_t parameter. The
fcntl(2) contains compatibility code to handle kernels before the
struct flock was changed during the 8.x CURRENT development. The
shims were reasonable to allow easier revert to the older kernel at
that time.
Now, two or three major releases later, shims do not serve any
purpose. Such old kernels cannot handle current libc, so revert the
compatibility code.
Make padded syscalls support conditional under the COMPAT6 config
option. For COMPAT32, the syscalls were under COMPAT6 already.
Remove WITHOUT_SYSCALL_COMPAT build option, which only purpose was to
(partially) disable the removed shims.
Reviewed by: jhb, imp (previous versions)
Discussed with: peter
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
waitid() function is required to be cancellable by the standard. The
wait6() and ppoll() follow the other syscalls in their groups.
Reviewed by: jhb, jilles (previous versions)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Note that to cancel blocked kevent(2) call, changelist must be empty,
since we cannot cancel a call which already made changes to the
process state. And in reverse, call which only makes changes to the
kqueue state, without waiting for an event, is not cancellable. This
makes a natural usage model to migrate kqueue loop to support
cancellation, where existing single kevent(2) call must be split into
two: first uncancellable update of kqueue, then cancellable wait for
events.
Note that this is ABI-incompatible change, but it is believed that
there is no cancel-safe code that relies on kevent(2) not being a
cancellation point. Option to preserve the ABI would be to keep
kevent(2) as is, but add new call with flags to specify cancellation
behaviour, which only value seems to add complications.
Suggested and reviewed by: jilles
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Errors from _thr_umutex_unlock2 should "never happen" in normal
circumstances. If they do, however, return them to the application
so it can fail early and loudly. Hiding the errors will only delay
the inevitable failure, making it harder to find and diagnose.
Submitted by: Eric van Gyzen <eric_van_gyzen@dell.com>
Obtained from: Dell Inc.
PR: 198914
MFC after: 1 week
particular, stdio locking was affected.
Reported and tested by: "Matthew D. Fuller" <fullermd@over-yonder.net>
Sponsored by: The FreeBSD Foundation
MFC after: 3 days
b_destroying member was left uninitialized, which caused spurious
EBUSY.
PR: 197365
Noted by: Florent Guiliani <fguiliani@verisign.com>
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
The amd64, i386, and sparc64 versions were identical, with the one
difference where the former two used inline asm instead of _tcb_get. I
have compared the function before and after replacing the asm with _tcb_get
and found the object files to be identical.
The arm, mips, and powerpc versions were almost identical. The only
difference was the powerpc version used an alignment of 1 where arm and
mips used 16. As this is an increase in alignment is will be safe.
Along with this arm, mips, and powerpc all passed, when initial was true,
the value returned from _tcb_get as the first argument to
_rtld_allocate_tls. This would then return this pointer back to the caller.
We can remove these extra calls by checking if initial is set and setting
the thread control block directly. As this is what the sparc64 code does
we can use it directly.
As after these observations all the architectures can now have identical
code we can merge them into a common file.
Differential Revision: https://reviews.freebsd.org/D1556
Reviewed by: kib
Sponsored by: The FreeBSD Foundation
cancellation-handling code in the libthr. Translate some syscalls
into their more generic counterpart, and remove translated syscalls
from the table.
List of the affected syscalls:
creat, open -> openat
raise -> thr_kill
sleep, usleep -> nanosleep
pause -> sigsuspend
wait, wait3, waitpid -> wait4
Suggested and reviewed by: jilles (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
though GOT, by staticizing and hiding. Add setter for
__error_selector to hide it as well.
Suggested and reviewed by: jilles
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
(or loading a dso linked to libthr.so into process which was not
linked against threading library).
- Remove libthr interposers of the libc functions, including
__error(). Instead, functions calls are indirected through the
interposing table, similar to how pthread stubs in libc are already
done. Libc by default points either to syscall trampolines or to
existing libc implementations. On libthr load, libthr rewrites the
pointers to the cancellable implementations already in libthr. The
interposition table is separate from pthreads stubs indirection
table to not pull pthreads stubs into static binaries.
- Postpone the malloc(3) internal mutexes initialization until libthr
is loaded. This avoids recursion between calloc(3) and static
pthread_mutex_t initialization.
- Reinstall signal handlers with wrapper on libthr load. The
_rtld_is_dlopened(3) is used to avoid useless calls to sigaction(2)
when libthr is statically referenced from the main binary.
In the process, fix openat(2), swapcontext(2) and setcontext(2)
interposing. The libc symbols were exported at different versions
than libthr interposers. Export both libc and libthr versions from
libc now, with default set to the higher version from libthr.
Remove unused and disconnected swapcontext(3) userspace implementation
from libc/gen.
No objections from: deischen
Tested by: pho, antoine (exp-run) (previous versions)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
It is automatically set when -fPIC is passed to the compiler.
Reviewed by: dim, kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D1179
stack into the stacks of the created threads. Add knob
LIBPTHREAD_SPLITSTACK_MAIN to restore the older behaviour.
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
the whole RLIMIT_STACK-sized region of the kernel-allocated stack as
the stack of main thread.
By default, the main thread stack is clamped at 2MB (4MB on 64bit
ABIs) and the rest is used for other threads stack allocation. Since
there is no programmatic way to adjust the size of the main thread
stack, pthread_attr_setstacksize() is too late, the knob allows user
to manage the main stack size both for single-threaded and
multi-threaded processes with the rlimit.
Reported by: "Ivan A. Kosarev" <ivan@ivan-labs.com>
Tested by: dim
Sponsored by: The FreeBSD Foundation
MFC after: 3 days
mode. This allows the binder to be functional in the child after the
fork (assuming no lazy loading of a filter is needed), but other rtld
services which require write lock on rtld_bind_lock cause deadlock, if
called by child.
Change the _rtld_atfork() to lock the bind lock in write mode, making
the rtld fully functional after the fork.
Pre-resolve the symbols which are called by the libthr' fork()
interposer, since dynamic resolution causes deadlock due to the
rtld_bind_lock already owned in the write mode.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
the signal second time, by adding the missed else before if statement.
While there, postpone initializing local curthread variable until
passed signal number is checked for validity.
Submitted by: John Wolfe <jlw@xinuos.com>
PR: threads/186309
MFC after: 1 week
unlocking the rtld bind lock results in the processing of ast and
recursing into the check_deferred_signal(). Nested execution of
check_deferred_signal() delivers the signal to user code and clears
si_signo. On return, top-level check_deferred_signal() frame
continues delivering the same signal one more time, but now with zero
si_signo.
Fix this by adding a flag to indicate that deferred delivery is
running, so check_deferred_signal() should avoid doing anything. Since
user signal handler is allowed to modify the passed machine context to
make return from the signal handler to cause arbitrary jump, or do
longjmp(). For this case, also clear the flag in thr_sighandler(),
since kernel signal delivery means that nested delivery code should
not run right now.
Reported by: Vitaly Magerya <vmagerya@gmail.com>
Reviewed by: davidxu, jilles
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
cancellation point. When enabling the cancellation, only process the
pending cancellation for asynchronous mode.
Reported and reviewed by: Kohji Okuno <okuno.kohji@jp.panasonic.com>
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
identified, unify the code of check_deferred_signal() for all
architectures, making the variant under #ifdef x86 common.
Tested by: marius (sparc64)
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
check_deferred_signal() returns twice, since handle_signal() emulates
the return from the normal signal handler by sigreturn(2)ing the
passed context. Second return is performed on the destroyed stack
frame, because __fillcontextx() has already returned. This causes
undefined and bad behaviour, usually the victim thread gets SIGSEGV.
Avoid nested frame and the need to return from it by doing direct call
to getcontext() in the check_deferred_signal() and using a new private
libc helper __fillcontextx2() to complement the context with the
extended CPU state if the deferred signal is still present.
The __fillcontextx() is now unused, but is kept to allow older
libthr.so to be used with the new libc.
Mark __fillcontextx() as returning twice [1].
Reported by: pgj
Pointy hat to: kib
Discussed with: dim
Tested by: pgj, dim
Suggested by: jilles [1]
MFC after: 1 week
The accept4() function, compared to accept(), allows setting the new file
descriptor atomically close-on-exec and explicitly controlling the
non-blocking status on the new socket. (Note that the latter point means
that accept() is not equivalent to any form of accept4().)
The linuxulator's accept4 implementation leaves a race window where the new
file descriptor is not close-on-exec because it calls sys_accept(). This
implementation leaves no such race window (by using falloc() flags). The
linuxulator could be fixed and simplified by using the new code.
Like accept(), accept4() is async-signal-safe, a cancellation point and
permitted in capability mode.
The threaded rtld lock implementation is faster even in the single-threaded
case because it postpones signal handlers via THR_CRITICAL_ENTER and
THR_CRITICAL_LEAVE instead of calling sigprocmask(2).
As a result, exception handling becomes faster in single-threaded
applications linked with libthr.
Reviewed by: kib
pthread_suspend_all_np() may have already suspended its parent thread.
Add locking code in pthread_suspend_all_np() to only allow one thread
to suspend other threads, this eliminates a deadlock where two or more
threads try to suspend each others.
Enqueue thread in LIFO, this can cause starvation, but it gives better
performance. Use _thr_queuefifo to control the frequency of FIFO vs LIFO,
you can use environment string LIBPTHREAD_QUEUE_FIFO to configure the
variable.
a mutex after a thread has unlocked it, it event writes data to the mutex
memory to clear contention bit, there is a race that other threads
can lock it and unlock it, then destroy it, so it should not write
data to the mutex memory if there isn't any waiter.
The new operation UMTX_OP_MUTEX_WAKE2 try to fix the problem. It
requires thread library to clear the lock word entirely, then
call the WAKE2 operation to check if there is any waiter in kernel,
and try to wake up a thread, if necessary, the contention bit is set again
by the operation. This also mitgates the chance that other threads find
the contention bit and try to enter kernel to compete with each other
to wake up sleeping thread, this is unnecessary. With this change, the
mutex owner is no longer holding the mutex until it reaches a point
where kernel umtx queue is locked, it releases the mutex as soon as
possible.
Performance is improved when the mutex is contensted heavily. On Intel
i3-2310M, the runtime of a benchmark program is reduced from 26.87 seconds
to 2.39 seconds, it even is better than UMTX_OP_MUTEX_WAKE which is
deprecated now. http://people.freebsd.org/~davidxu/bench/mutex_perf.c
example, it uses a serialization point like following:
pthread_mutex_lock(&mutex);
pthread_mutex_unlock(&mutex);
pthread_mutex_destroy(&muetx);
They think a previous lock holder should have already left the mutex and
is no longer referencing it, so they destroy it. To be maximum compatible
with such code, we use IA64 version to unlock the mutex in kernel, remove
the two steps unlocking code.
