src/lib/libc_r/uthread/uthread_fd.c, branch main

Remove libc_r threading library. It has been disconnected from the build

2010-11-13T22:22:18Z

for four years (since r162846). Submitted by: Alexander Best arundel@

Remove 3rd clause, renumber, ok per email

2007-01-12T07:26:21Z

Remove much of the dereferencing of the fd table entries to look

2002-08-29T23:06:07Z

at file flags and replace it with functions that will avoid null pointer checks. MFC to be done by archie ;-) PR: 42100 Reviewed by: archie, robert MFC after: 3 days

In the words of the submitter:

2001-10-21T18:23:50Z

In libc_r, if _FDLOCKS_ENABLED is not defined, there is no guarantee in many of the sycall wrappers that _thread_fd_table[fd] is initialized. This causes problems for programs that pass in file descriptors and execve() another program; when the exec'ed program tries to do an fcntl() or other syscall on the passed-in fd, it fails. Add calls to initialize the FD table entry for _thread_fd_lock and _thread_fd_lock_debug. Submitted by: Peter S. Housel

Remove (int) file descriptor locking. It should be up to the

2001-02-11T22:07:32Z

application to provide locking for I/O operations. This doesn't break any of my tests, but the old behavior can be restored by compiling with _FDLOCKS_ENABLED. This will eventually be removed when it is obvious it does not cause any problems. Remove most of flockfile implementation, with the exception of flockfile_debug. Make error messages more informational (submitted by Mike Heffner , who's now known as mikeh@FreeBSD.org).

_exit in libc is now __sys_exit not sysexit.

2001-01-29T03:24:23Z

Add another check for thread library initialization (jdp, we really need a way to get _thread_init called at program start before any constructors are run).

Add weak definitions for wrapped system calls. In general:

2001-01-24T13:03:38Z

_foo - wrapped system call foo - weak definition to _foo and for cancellation points: _foo - wrapped system call __foo - enter cancellation point, call _foo(), leave cancellation point foo - weak definition to __foo Change use of global _thread_run to call a function to get the currently running thread. Make all pthread_foo functions weak definitions to _pthread_foo, where _pthread_foo is the implementation. This allows an application to provide its own pthread functions. Provide slightly different versions of pthread_mutex_lock and pthread_mutex_init so that we can tell the difference between a libc mutex and an application mutex. Threads holding mutexes internal to libc should never be allowed to exit, call signal handlers, or cancel. Approved by: -arch

Implement zero system call thread switching. Performance of

2000-10-13T22:12:32Z

thread switches should be on par with that under scheduler activations. o Timing is achieved through the use of a fixed interval timer (ITIMER_PROF) to count scheduling ticks instead of retrieving the time-of-day upon every thread switch and calculating elapsed real time. o Polling for I/O readiness is performed once for each scheduling tick instead of every thread switch. o The non-signal saving/restoring versions of setjmp/longjmp are used to save and restore thread contexts. This may allow the removal of _THREAD_SAFE macros from setjmp() and longjmp() - needs more investigation. Change signal handling so that signals are handled in the context of the thread that is receiving the signal. When signals are dispatched to a thread, a special signal handling frame is created on top of the target threads stack. The frame contains the threads saved state information and a new context in which the thread can run. The applications signal handler is invoked through a wrapper routine that knows how to restore the threads saved state and unwind to previous frames. Fix interruption of threads due to signals. Some states were being improperly interrupted while other states were not being interrupted. This should fix several PRs. Signal handlers, which are invoked as a result of a process signal (not by pthread_kill()), are now called with the code (or siginfo_t if SA_SIGINFO was set in sa_flags) and sigcontext_t as received from the process signal handler. Modify the search for a thread to which a signal is delivered. The search algorithm is now: o First thread found in sigwait() with signal in wait mask. o First thread found sigsuspend()'d on the signal. o Current thread if signal is unmasked. o First thread found with signal unmasked. Collapse machine dependent support into macros defined in pthread_private.h. These should probably eventually be moved into separate MD files. Change the range of settable priorities to be compliant with POSIX (0-31). The threads library uses higher priorities internally for real-time threads (not yet implemented) and threads executing signal handlers. Real-time threads and threads running signal handlers add 64 and 32, respectively, to a threads base priority. Some other small changes and cleanups. PR: 17757 18559 21943 Reviewed by: jasone

Implement continuations to correctly handle [sig|_]longjmp() inside of a

2000-01-19T07:04:50Z

signal handler. Explicitly check for jumps to anywhere other than the current stack, since such jumps are undefined according to POSIX. While we're at it, convert thread cancellation to use continuations, since it's cleaner than the original cancellation code. Avoid delivering a signal to a thread twice. This was a pre-existing bug, but was likely unexposed until these other changes were made. Defer signals generated by pthread_kill() so that they can be delivered on the appropriate stack. deischen claims that this is unnecessary, which is likely true, but without this change, pthread_kill() can cause undefined priority queue states and/or PANICs in [sig|_]longjmp(), so I'm leaving this in for now. To compile this code out and exercise the bug, define the _NO_UNDISPATCH cpp macro. Defining _PTHREADS_INVARIANTS as well will cause earlier crashes. PR: kern/14685 Collaboration with: deischen

Fix problems with cancellation while in critical regions.

1999-12-17T00:57:54Z

o Cancellation flags were not getting properly set/cleared. o Loops waiting for internal locks were not being exited correctly by a cancelled thread. o Minor spelling (cancelation -> cancellation) and formatting corrections (missing tab). Found by: tg Reviewed by: jasone