Commit Graph

31 Commits

Author SHA1 Message Date
Eric van Gyzen
dbb1c64e82 Use _thr_isthreaded() and _thr_setthreaded() wrappers
...instead of directly using the global variable.

MFC after:	2 weeks
Sponsored by:	Dell EMC Isilon
2018-11-30 03:02:49 +00:00
Pedro F. Giffuni
8a16b7a18f General further adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
2017-11-20 19:49:47 +00:00
Konstantin Belousov
3279301186 Use __FBSDID() for .c files from lib/libthr/thread.
Sponsored by:	The FreeBSD Foundation
2016-04-08 11:15:26 +00:00
Konstantin Belousov
53fd961f05 Lock pshared_lock shared around fork, to ensure that the COW snapshot
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
2016-03-21 06:52:35 +00:00
Konstantin Belousov
d6717e1b51 Typo. 2015-12-27 01:14:42 +00:00
Konstantin Belousov
8495e8b1e9 Fix known issues which blow up the process after dlopen("libthr.so")
(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
2015-01-03 18:38:46 +00:00
Konstantin Belousov
1c70d00733 Right now, the rtld prefork hook locks the rtld bind lock in the read
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
2014-05-24 10:23:06 +00:00
David Xu
0aa81bff0b Eliminate redundant code, _thr_spinlock_init() has already been called
in init_private(), don't call it again in fork() wrapper.
2012-08-23 05:15:15 +00:00
David Xu
93ea4a71bf In most cases, cancel_point and cancel_async needn't be checked again,
because cancellation is almostly checked at cancellation points.
2010-09-24 07:52:07 +00:00
David Xu
4173ebef4f Because atfork lock is held while forking, a thread cancellation triggered
by atfork handler is unsafe, use intenal flag no_cancel to disable it.
2010-09-19 09:03:11 +00:00
David Xu
a9b764e218 Convert thread list lock from mutex to rwlock. 2010-09-13 07:03:01 +00:00
David Xu
12c61c22ce In function __pthread_cxa_finalize(), also make code for removing
atfork handler be async-signal safe.
2010-09-01 07:09:46 +00:00
David Xu
a523216bc6 pthread_atfork should acquire writer lock and protect the code
with critical region.
2010-09-01 03:55:10 +00:00
David Xu
ada33a6e36 Change atfork lock from mutex to rwlock, also make mutexes used by malloc()
module private type, when private type mutex is locked/unlocked, thread
critical region is entered or leaved. These changes makes fork()
async-signal safe which required by POSIX. Note that user's atfork handler
still needs to be async-signal safe, but it is not problem of libthr, it
is user's responsiblity.
2010-09-01 03:11:21 +00:00
David Xu
02c3c85869 Add signal handler wrapper, the reason to add it becauses there are
some cases we want to improve:
  1) if a thread signal got a signal while in cancellation point,
     it is possible the TDP_WAKEUP may be eaten by signal handler
     if the handler called some interruptibly system calls.
  2) In signal handler, we want to disable cancellation.
  3) When thread holding some low level locks, it is better to
     disable signal, those code need not to worry reentrancy,
     sigprocmask system call is avoided because it is a bit expensive.
The signal handler wrapper works in this way:
  1) libthr installs its signal handler if user code invokes sigaction
     to install its handler, the user handler is recorded in internal
     array.
  2) when a signal is delivered, libthr's signal handler is invoke,
     libthr checks if thread holds some low level lock or is in critical
     region, if it is true, the signal is buffered, and all signals are
     masked, once the thread leaves critical region, correct signal
     mask is restored and buffered signal is processed.
  3) before user signal handler is invoked, cancellation is temporarily
     disabled, after user signal handler is returned, cancellation state
     is restored, and pending cancellation is rescheduled.
2010-09-01 02:18:33 +00:00
David Xu
ed0ee6af2e Unregister thread specific data destructor when a corresponding dso
is unloaded.
2010-08-27 05:20:22 +00:00
Konstantin Belousov
ea246b6369 On shared object unload, in __cxa_finalize, call and clear all installed
atexit and __cxa_atexit handlers that are either installed by unloaded
dso, or points to the functions provided by the dso.

Use _rtld_addr_phdr to locate segment information from the address of
private variable belonging to the dso, supplied by crtstuff.c. Provide
utility function __elf_phdr_match_addr to do the match of address against
dso executable segment.

Call back into libthr from __cxa_finalize using weak
__pthread_cxa_finalize symbol to remove any atfork handler which
function points into unloaded object.

The rtld needs private __pthread_cxa_finalize symbol to not require
resolution of the weak undefined symbol at initialization time. This
cannot work, since rtld is relocated before sym_zero is set up.

Idea by:	kan
Reviewed by:	kan (previous version)
MFC after:	3 weeks
2010-08-23 15:38:02 +00:00
Brian Feldman
43af51a2b5 These are some cosmetic changes to improve the clarity of libthr's fork implementation. 2009-05-11 16:45:53 +00:00
Konstantin Belousov
29986e1bac Forcibly unlock the malloc() locks in the child process after fork(),
by temporary pretending that the process is still multithreaded.
Current malloc lock primitives do nothing for singlethreaded process.

Reviewed by:	davidxu, deischen
2009-03-19 10:32:25 +00:00
Konstantin Belousov
10b4034657 Provide custom simple allocator for rtld locks in libthr. The allocator
does not use any external symbols, thus avoiding possible recursion into
rtld to resolve symbols, when called.

Reviewed by:	kan, davidxu
Tested by:	rink
MFC after:	1 month
2008-12-02 11:58:31 +00:00
Alexander Kabaev
97df383415 Invoke _rtld_atfork_post earlier, before we reinitialize rtld locks
by switching into single-thread mode.

libthr ignores broken use of lock bitmaps used by default rtld locking
implementation, this in turn turns lock handoff in _rtld_thread_init
into NOP. This in turn makes child processes of forked multi-threaded
programs to run with _thr_signal_block still in effect, with most
signals blocked.

Reported by: phk, kib
2008-12-01 21:00:25 +00:00
Konstantin Belousov
e711c6f0d1 Unlock the malloc() locks in the child process after fork(). This gives
us working malloc in the fork child of the multithreaded process.

Although POSIX requires that only async-signal safe functions shall be
operable after fork in multithreaded process, not having malloc lower
the quality of our implementation.

Tested by:	rink
Discussed with:	kan, davidxu
Reviewed by:	kan
MFC after:	1 month
2008-11-29 21:46:28 +00:00
Konstantin Belousov
cb5c4b10ba Add two rtld exported symbols, _rtld_atfork_pre and _rtld_atfork_post.
Threading library calls _pre before the fork, allowing the rtld to
lock itself to ensure that other threads of the process are out of
dynamic linker. _post releases the locks.

This allows the rtld to have consistent state in the child. Although
child may legitimately call only async-safe functions, the call may
need plt relocation resolution, and this requires working rtld.

Reported and debugging help by:	rink
Reviewed by:	kan, davidxu
MFC after:	1 month (anyway, not before 7.1 is out)
2008-11-27 11:27:59 +00:00
Warner Losh
fed32d7544 Remove 3rd clause, renumber, ok per email 2007-01-12 07:26:21 +00:00
David Xu
f08e1bf682 Eliminate atomic operations in thread cancellation functions, it should
reduce overheads of cancellation points.
2006-11-24 09:57:38 +00:00
David Xu
5656b5fafa Don't inherit THR_FLAGS_NEED_SUSPEND for child process, child process
only has one thread, setting the flag can cause the thread to be
suspended and no another thread will resume it.
2006-10-14 13:40:08 +00:00
David Xu
bddd24cd9c Replace internal usage of struct umtx with umutex which can supports
real-time if we want, no functionality is changed.
2006-09-06 04:04:10 +00:00
David Xu
37a6356bbe WARNS level 4 cleanup. 2006-04-04 02:57:49 +00:00
Jason Evans
52828c0e9c In preparation for a new malloc implementation:
* Add posix_memalign().

  * Move calloc() from calloc.c to malloc.c.  Add a calloc() implementation in
    rtld-elf in order to make the loader happy (even though calloc() isn't
    used in rtld-elf).

  * Add _malloc_prefork() and _malloc_postfork(), and use them instead of
    directly manipulating __malloc_lock.

Approved by:	phk, markm (mentor)
2006-01-12 07:28:21 +00:00
David Xu
97986a2ea0 Remove in-progress wait code to sync with libpthread's behavior. 2006-01-03 13:30:23 +00:00
David Xu
a091d823ad Import my recent 1:1 threading working. some features improved includes:
1. fast simple type mutex.
 2. __thread tls works.
 3. asynchronous cancellation works ( using signal ).
 4. thread synchronization is fully based on umtx, mainly, condition
    variable and other synchronization objects were rewritten by using
    umtx directly. those objects can be shared between processes via
    shared memory, it has to change ABI which does not happen yet.
 5. default stack size is increased to 1M on 32 bits platform, 2M for
    64 bits platform.
As the result, some mysql super-smack benchmarks show performance is
improved massivly.

Okayed by: jeff, mtm, rwatson, scottl
2005-04-02 01:20:00 +00:00