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* fix race condition in pthread_killRich Felker2011-06-141-0/+1
| | | | | | | | | | | | | | if thread id was reused by the kernel between the time pthread_kill read it from the userspace pthread_t object and the time of the tgkill syscall, a signal could be sent to the wrong thread. the tgkill syscall was supposed to prevent this race (versus the old tkill syscall) but it can't; it can only help in the case where the tid is reused in a different process, but not when the tid is reused in the same process. the only solution i can see is an extra lock to prevent threads from exiting while another thread is trying to pthread_kill them. it should be very very cheap in the non-contended case.
* fix sigset macro for 64-bit systems (<< was overflowing due to wrong type)Rich Felker2011-06-131-1/+1
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* implement uselocale function (minimal)Rich Felker2011-05-301-0/+2
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* optimize compound-literal sigset_t's not to contain useless hurd bitsRich Felker2011-05-071-2/+4
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* overhaul implementation-internal signal protectionsRich Felker2011-05-071-3/+6
| | | | | | | | | | | | | | | | | | | the new approach relies on the fact that the only ways to create sigset_t objects without invoking UB are to use the sig*set() functions, or from the masks returned by sigprocmask, sigaction, etc. or in the ucontext_t argument to a signal handler. thus, as long as sigfillset and sigaddset avoid adding the "protected" signals, there is no way the application will ever obtain a sigset_t including these bits, and thus no need to add the overhead of checking/clearing them when sigprocmask or sigaction is called. note that the old code actually *failed* to remove the bits from sa_mask when sigaction was called. the new implementations are also significantly smaller, simpler, and faster due to ignoring the useless "GNU HURD signals" 65-1024, which are not used and, if there's any sanity in the world, never will be used.
* completely new barrier implementation, addressing major correctness issuesRich Felker2011-05-061-4/+4
| | | | | | | | | | | | | | | | | | | | the previous implementation had at least 2 problems: 1. the case where additional threads reached the barrier before the first wave was finished leaving the barrier was untested and seemed not to be working. 2. threads leaving the barrier continued to access memory within the barrier object after other threads had successfully returned from pthread_barrier_wait. this could lead to memory corruption or crashes if the barrier object had automatic storage in one of the waiting threads and went out of scope before all threads finished returning, or if one thread unmapped the memory in which the barrier object lived. the new implementation avoids both problems by making the barrier state essentially local to the first thread which enters the barrier wait, and forces that thread to be the last to return.
* overhaul pthread cancellationRich Felker2011-04-171-1/+3
| | | | | | | | | | | | | | | | | | | | | | this patch improves the correctness, simplicity, and size of cancellation-related code. modulo any small errors, it should now be completely conformant, safe, and resource-leak free. the notion of entering and exiting cancellation-point context has been completely eliminated and replaced with alternative syscall assembly code for cancellable syscalls. the assembly is responsible for setting up execution context information (stack pointer and address of the syscall instruction) which the cancellation signal handler can use to determine whether the interrupted code was in a cancellable state. these changes eliminate race conditions in the previous generation of cancellation handling code (whereby a cancellation request received just prior to the syscall would not be processed, leaving the syscall to block, potentially indefinitely), and remedy an issue where non-cancellable syscalls made from signal handlers became cancellable if the signal handler interrupted a cancellation point. x86_64 asm is untested and may need a second try to get it right.
* use a separate signal from SIGCANCEL for SIGEV_THREAD timersRich Felker2011-04-141-0/+1
| | | | | | otherwise we cannot support an application's desire to use asynchronous cancellation within the callback function. this change also slightly debloats pthread_create.c.
* greatly improve SIGEV_THREAD timersRich Felker2011-04-091-0/+1
| | | | | calling pthread_exit from, or pthread_cancel on, the timer callback thread will no longer destroy the timer.
* move rsyscall out of pthread_create moduleRich Felker2011-04-061-0/+3
| | | | | | | | | | | | | | this is something of a tradeoff, as now set*id() functions, rather than pthread_create, are what pull in the code overhead for dealing with linux's refusal to implement proper POSIX thread-vs-process semantics. my motivations are: 1. it's cleaner this way, especially cleaner to optimize out the rsyscall locking overhead from pthread_create when it's not needed. 2. it's expected that only a tiny number of core system programs will ever use set*id() functions, whereas many programs may want to use threads, and making thread overhead tiny is an incentive for "light" programs to try threads.
* optimize timer creation and possibly protect against some minor racesRich Felker2011-03-301-2/+0
| | | | | | | | | the major idea of this patch is not to depend on having the timer pointer delivered to the signal handler, and instead use the thread pointer to get the callback function address and argument. this way, the parent thread can make the timer_create syscall while the child thread is starting, and it should never have to block waiting for the barrier.
* major improvements to cancellation handlingRich Felker2011-03-291-2/+5
| | | | | | | | | | | | | - there is no longer any risk of spoofing cancellation requests, since the cancel flag is set in pthread_cancel rather than in the signal handler. - cancellation signal is no longer unblocked when running the cancellation handlers. instead, pthread_create will cause any new threads created from a cancellation handler to unblock their own cancellation signal. - various tweaks in preparation for POSIX timer support.
* some preliminaries for adding POSIX timersRich Felker2011-03-291-0/+4
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* remove useless field in pthread struct (wasted a good bit of space)Rich Felker2011-03-281-1/+0
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* implement robust mutexesRich Felker2011-03-171-0/+5
| | | | | | some of this code should be cleaned up, e.g. using macros for some of the bit flags, masks, etc. nonetheless, the code is believed to be working and correct at this point.
* reorder mutex struct fields to make room for pointers (upcoming robust mutexes)Rich Felker2011-03-171-1/+3
| | | | | | the layout has been chosen so that pointer slots 3 and 4 fit between the integer slots on 32-bit archs, and come after the integer slots on 64-bit archs.
* unify lock and owner fields of mutex structureRich Felker2011-03-171-1/+0
| | | | | | this change is necessary to free up one slot in the mutex structure so that we can use doubly-linked lists in the implementation of robust mutexes.
* optimize pthread termination in the non-detached caseRich Felker2011-03-101-0/+1
| | | | | | | we can avoid blocking signals by simply using a flag to mark that the thread has exited and prevent it from getting counted in the rsyscall signal-pingpong. this restores the original pthread create/join throughput from before the sigprocmask call was added.
* fix and optimize non-default-type mutex behaviorRich Felker2011-03-081-0/+1
| | | | | | | | | problem 1: mutex type from the attribute was being ignored by pthread_mutex_init, so recursive/errorchecking mutexes were never being used at all. problem 2: ownership of recursive mutexes was not being enforced at unlock time.
* use the selected clock from the condattr for pthread_cond_timedwaitRich Felker2011-03-071-0/+1
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* reorganize pthread data structures and move the definitions to alltypes.hRich Felker2011-02-171-0/+19
| | | | | | | | this allows sys/types.h to provide the pthread types, as required by POSIX. this design also facilitates forcing ABI-compatible sizes in the arch-specific alltypes.h, while eliminating the need for developers changing the internals of the pthread types to poke around with arch-specific headers they may not be able to test.
* finish unifying thread register handling in preparation for portingRich Felker2011-02-151-8/+2
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* begin unifying clone/thread management interface in preparation for portingRich Felker2011-02-151-5/+3
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* initial check-in, version 0.5.0 v0.5.0Rich Felker2011-02-121-0/+68