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
the constraints on what needs to be installed in a specific to
maintain consistency during upgrades.
Create a new clibs package containing libraries that are needed
as a bare minimum for consistency.
With much help and input from: kib
Sponsored by: The FreeBSD Foundation
RISC-V is a new ISA designed to support computer research and education, and
is now become a standard open architecture for industry implementations.
This is a minimal set of changes required to run 'make kernel-toolchain'
using external (GNU) toolchain.
The FreeBSD/RISC-V project home: https://wiki.freebsd.org/riscv.
Reviewed by: andrew, bdrewery, emaste, imp
Sponsored by: DARPA, AFRL
Sponsored by: HEIF5
Differential Revision: https://reviews.freebsd.org/D4445
This both avoids some dependencies on xinstall.host and allows
bootstrapping on older releases to work due to lack of at least 'install -l'
support.
Sponsored by: EMC / Isilon Storage Division
netbsd-tests.test.mk (r289151)
- Eliminate explicit OBJTOP/SRCTOP setting
- Convert all ad hoc NetBSD test integration over to netbsd-tests.test.mk
- Remove unnecessary TESTSDIR setting
- Use SRCTOP where possible for clarity
MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Divison
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
Clang emits SSE instructions on amd64 in the common path of
pthread_mutex_unlock. If the thread does not otherwise use SSE,
this usage incurs a context-switch of the FPU/SSE state, which
reduces the performance of multiple real-world applications by a
non-trivial amount (3-5% in one application).
Instead of this change, I experimented with eagerly switching the
FPU state at context-switch time. This did not help. Most of the
cost seems to be in the read/write of memory--as kib@ stated--and
not in the #NM handling. I tested on machines with and without
XSAVEOPT.
One counter-argument to this change is that most applications already
use SIMD, and the number of applications and amount of SIMD usage
are only increasing. This is absolutely true. I agree that--in
general and in principle--this change is in the wrong direction.
However, there are applications that do not use enough SSE to offset
the extra context-switch cost. SSE does not provide a clear benefit
in the current libthr code with the current compiler, but it does
provide a clear loss in some cases. Therefore, disabling SSE in
libthr is a non-loss for most, and a gain for some.
I refrained from disabling SSE in libc--as was suggested--because
I can't make the above argument for libc. It provides a wide variety
of code; each case should be analyzed separately.
https://lists.freebsd.org/pipermail/freebsd-current/2015-March/055193.html
Suggestions from: dim, jmg, rpaulo
Approved by: kib (mentor)
MFC after: 2 weeks
Sponsored by: Dell Inc.
Since METAMODE has been added, sys.mk loads bsd.mkopt.mk which ends load loading
bsd.own.mk which then defines SHLIBDIR before all the Makefile.inc everywhere.
This makes /lib being populated again.
Reported by: many
Off by default, build behaves normally.
WITH_META_MODE we get auto objdir creation, the ability to
start build from anywhere in the tree.
Still need to add real targets under targets/ to build packages.
Differential Revision: D2796
Reviewed by: brooks imp
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
