Rich Felker b470030f83 overhaul cancellation to fix resource leaks and dangerous behavior with signals ... this commit addresses two issues: 1. a race condition, whereby a cancellation request occurring after a syscall returned from kernelspace but before the subsequent CANCELPT_END would cause cancellable resource-allocating syscalls (like open) to leak resources. 2. signal handlers invoked while the thread was blocked at a cancellation point behaved as if asynchronous cancellation mode wer in effect, resulting in potentially dangerous state corruption if a cancellation request occurs. the glibc/nptl implementation of threads shares both of these issues. with this commit, both are fixed. however, cancellation points encountered in a signal handler will not be acted upon if the signal was received while the thread was already at a cancellation point. they will of course be acted upon after the signal handler returns, so in real-world usage where signal handlers quickly return, it should not be a problem. it's possible to solve this problem too by having sigaction() wrap all signal handlers with a function that uses a pthread_cleanup handler to catch cancellation, patch up the saved context, and return into the cancellable function that will catch and act upon the cancellation. however that would be a lot of complexity for minimal if any benefit...		2011-03-24 14:18:00 -04:00
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bits	fix typo in x86_64 part of syscall overhaul	2011-03-19 21:50:20 -04:00
atomic.h	optimize contended normal mutex case; add int compare-and-swap atomic	2011-03-17 12:14:40 -04:00
pthread_arch.h	overhaul cancellation to fix resource leaks and dangerous behavior with signals	2011-03-24 14:18:00 -04:00