AgeCommit message (Collapse)AuthorLines
2011-10-05fix fcntl O_* flags for armRich Felker-4/+4
no idea why these 4 are permuted and the rest are standard/generic
2011-10-04make [U]INTn_C() macros have the right type...Rich Felker-4/+4
...and still be valid in #if directives.
2011-10-03recovering ownerdead robust mutex must reset recursive lock countRich Felker-0/+1
2011-10-03simplify robust mutex unlock code pathRich Felker-4/+4
right now it's questionable whether this change is an improvement or not, but if we later want to support priority inheritance mutexes, it will be important to have the code paths unified like this to avoid major code duplication.
2011-10-03fix crash if pthread_mutex_unlock is called without ever lockingRich Felker-1/+1
this is valid for error-checking mutexes; otherwise it invokes UB and would be justified in crashing.
2011-10-03use count=0 instead of 1 for recursive mutex with only one lock referenceRich Felker-4/+2
this simplifies the code paths slightly, but perhaps what's nicer is that it makes recursive mutexes fully reentrant, i.e. locking and unlocking from a signal handler works even if the interrupted code was in the middle of locking or unlocking.
2011-10-03sysconf for PTHREAD_KEYS_MAXRich Felker-1/+1
2011-10-02synchronize cond var destruction with exiting waitsRich Felker-0/+12
2011-10-01fix failure-to-wake in rwlock unlockRich Felker-1/+1
a reader unlocking the lock need only wake one waiter (necessarily a writer, but a writer unlocking the lock must wake all waiters (necessarily readers). if it only wakes one, the remainder can remain blocked indefinitely, or at least until the first reader unlocks (in which case the whole lock becomes serialized and behaves as a mutex rather than a read lock).
2011-10-01dlsym entry point for armRich Felker-0/+6
2011-10-01dynamic linker entry point for armRich Felker-0/+14
mildly tested, seems to work
2011-10-01typo (copy 2) in arm reloc.hRich Felker-1/+1
2011-10-01typo in arm reloc.hRich Felker-1/+1
2011-10-01first attempt at arm dynamic linkingRich Felker-0/+26
2011-09-29fix various bugs in path and error handling in execvp/fexecveRich Felker-18/+29
2011-09-28don't crash on null strings in printfRich Felker-1/+1
passing null pointer for %s is UB but lots of broken programs do it anyway
2011-09-28fix excessive/insufficient wakes in __vm_unlockRich Felker-3/+3
there is no need to send a wake when the lock count does not hit zero, but when it does, all waiters must be woken (since all with the same sign are eligible to obtain the lock).
2011-09-28make getmntent_r discard long lines when it returns error, not seek backRich Felker-2/+1
seeking back can be performed by the caller, but if the caller doesn't expect it, it will result in an infinite loop of failures.
2011-09-28improve pshared barriersRich Felker-12/+14
eliminate the sequence number field and instead use the counter as the futex because of the way the lock is held, sequence numbers are completely useless, and this frees up a field in the barrier structure to be used as a waiter count for the count futex, which lets us avoid some syscalls in the best case. as of now, self-synchronized destruction and unmapping should be fully safe. before any thread can return from the barrier, all threads in the barrier have obtained the vm lock, and each holds a shared lock on the barrier. the barrier memory is not inspected after the shared lock count reaches 0, nor after the vm lock is released.
2011-09-28next step making barrier self-sync'd destruction safeRich Felker-6/+18
i think this works, but it can be simplified. (next step)
2011-09-28barrier destroy must also wait for threads in other processes exiting barrierRich Felker-0/+2
the vm lock only waits for threads in the same process exiting. actually this fix is not enough, but it's a start...
2011-09-28stupid typo (caused by rather ugly spelling in POSIX..) in aioRich Felker-2/+2
2011-09-27correctly handle the degenerate barrier in the pshared caseRich Felker-1/+1
2011-09-27fix crash in pthread_cond_wait mutex-locked checkRich Felker-1/+1
it was assuming the result of the condition it was supposed to be checking for, i.e. that the thread ptr had already been initialized by pthread_mutex_lock. use the slower call to be safe.
2011-09-27fix crash in pthread_testcancel if pthread_self has not been calledRich Felker-1/+1
2011-09-27improve/debloat mutex unlock error checking in pthread_cond_waitRich Felker-3/+3
we're not required to check this except for error-checking mutexes, but it doesn't hurt. the new test is actually simpler/lighter, and it also eliminates the need to later check that pthread_mutex_unlock succeeds.
2011-09-27check mutex owner in pthread_cond_waitRich Felker-0/+3
when used with error-checking mutexes, pthread_cond_wait is required to fail with EPERM if the mutex is not locked by the caller. previously we relied on pthread_mutex_unlock to generate the error, but this is not valid, since in the case of such invalid usage the internal state of the cond variable has already been potentially corrupted (due to access outside the control of the mutex). thus, we have to check first.
2011-09-27fix pshared barrier wrong return value.Rich Felker-1/+1
i set the return value but then never used it... oops!
2011-09-27convert the barrier pshared option back to 0/1 values when getting itRich Felker-1/+1
2011-09-27improve error handling in mntent stuff...Rich Felker-2/+9
not sure if this is correct/ideal. it needs further attention.
2011-09-27fix missing va_end in prctl syscall wrapperRich Felker-0/+1
2011-09-27fix clobbering of errno in get(pw|gr)([ug]id|nam) by fcloseRich Felker-0/+12
2011-09-27process-shared barrier support, based on discussion with bdonlanRich Felker-16/+102
this implementation is rather heavy-weight, but it's the first solution i've found that's actually correct. all waiters actually wait twice at the barrier so that they can synchronize exit, and they hold a "vm lock" that prevents changes to virtual memory mappings (and blocks pthread_barrier_destroy) until all waiters are finished inspecting the barrier. thus, it is safe for any thread to destroy and/or unmap the barrier's memory as soon as pthread_barrier_wait returns, without further synchronization.
2011-09-27fix incorrect allocation failure check in pthread_createRich Felker-1/+1
mmap returns MAP_FAILED not 0 because some idiot thought the ability to mmap the null pointer page would be a good idea...
2011-09-26fix ctype macros to cast argument to (unsigned) firstRich Felker-7/+7
issue reported by nsz, but it's actually not just pedantic. the functions can take input of any arithmetic type, including floating point, and the behavior needs to be as if the conversion implicit in the function call took place.
2011-09-26another cond var fix: requeue count race conditionRich Felker-15/+13
lock out new waiters during the broadcast. otherwise the wait count added to the mutex might be lower than the actual number of waiters moved, and wakeups may be lost. this issue could also be solved by temporarily setting the mutex waiter count higher than any possible real count, then relying on the kernel to tell us how many waiters were requeued, and updating the counts afterwards. however the logic is more complex, and i don't really trust the kernel. the solution here is also nice in that it replaces some atomic cas loops with simple non-atomic ops under lock.
2011-09-26fix lost signals in cond varsRich Felker-14/+17
due to moving waiters from the cond var to the mutex in bcast, these waiters upon wakeup would steal slots in the count from newer waiters that had not yet been signaled, preventing the signal function from taking any action. to solve the problem, we simply use two separate waiter counts, and so that the original "total" waiters count is undisturbed by broadcast and still available for signal.
2011-09-26cleanup various minor issues reported by nszRich Felker-9/+9
the changes to syscall_ret are mostly no-ops in the generated code, just cleanup of type issues and removal of some implementation-defined behavior. the one exception is the change in the comparison value, which is fixed so that 0xf...f000 (which in principle could be a valid return value for mmap, although probably never in reality) is not treated as an error return.
2011-09-26redo cond vars again, use sequence numbersRich Felker-48/+52
testing revealed that the old implementation, while correct, was giving way too many spurious wakeups due to races changing the value of the condition futex. in a test program with 5 threads receiving broadcast signals, the number of returns from pthread_cond_wait was roughly 3 times what it should have been (2 spurious wakeups for every legitimate wakeup). moreover, the magnitude of this effect seems to grow with the number of threads. the old implementation may also have had some nasty race conditions with reuse of the cond var with a new mutex. the new implementation is based on incrementing a sequence number with each signal event. this sequence number has nothing to do with the number of threads intended to be woken; it's only used to provide a value for the futex wait to avoid deadlock. in theory there is a danger of race conditions due to the value wrapping around after 2^32 signals. it would be nice to eliminate that, if there's a way. testing showed no spurious wakeups (though they are of course possible) with the new implementation, as well as slightly improved performance.
2011-09-25revert previous change in cond var waiter moveRich Felker-2/+6
using swap has a race condition: the waiters must be added to the mutex waiter count *before* they are taken off the cond var waiter count, or wake events can be lost.
2011-09-25optimize cond waiter move using atomic swap instead of cas loopRich Felker-6/+2
2011-09-25fix logic for when wakeup is not desired on cond bcastRich Felker-3/+4
somehow i forgot that normal-type mutexes don't store the owner tid.
2011-09-25new futex-requeue-based pthread_cond_broadcast implementationRich Felker-7/+69
this avoids the "stampede effect" where pthread_cond_broadcast would result in all waiters waking up simultaneously, only to immediately contend for the mutex and go back to sleep.
2011-09-23fix ABA race in cond vars, improve them overallRich Felker-11/+12
previously, a waiter could miss the 1->0 transition of block if another thread set block to 1 again after the signal function set block to 0. we now use the caller's thread id as a unique token to store in block, which no other thread will ever write there. this ensures that if block still contains the tid, no signal has occurred. spurious wakeups will of course occur whenever there is a spurious return from the futex wait and another thread has begun waiting on the cond var. this should be a rare occurrence except perhaps in the presence of interrupting signal handlers. signal/bcast operations have been improved by noting that they need not avoid inspecting the cond var's memory after changing the futex value. because the standard allows spurious wakeups, there is no way for an application to distinguish between a spurious wakeup just before another thread called signal/bcast, and the deliberate wakeup resulting from the signal/bcast call. thus the woken thread must assume that the signalling thread may still be waiting to act on the cond var, and therefore it cannot destroy/unmap the cond var.
2011-09-23FD_ISSET must return an int. this is the easiest way.Rich Felker-1/+1
casting to int would not be correct because high bits could be lost. mapping the high bits down onto low bits would be costlier in the common case where the result is just used in a conditional. changing the type of the bit array elements to int would permute the order of the bit array on 64-bit big endian systems, so that's not an option either.
2011-09-23sys/user.h may need stdint.hRich Felker-0/+1
2011-09-22"optimize" arm __pthread_selfRich Felker-4/+1
actually this is just to avoid gcc being stupid and refusing to inline the function version, even when the size cost is essentially identical whether it's inlined or not.
2011-09-22fix deadlock in condition wait whenever there are multiple waitersRich Felker-5/+18
it's amazing none of the conformance tests i've run even bothered to check whether something so basic works...
2011-09-22fix x86_64 user.h (previously was just a copy of i386)Rich Felker-48/+13
2011-09-22cleanup/debloat i386 user.hRich Felker-43/+11