fbeb36e4bf
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
989 lines
26 KiB
C
989 lines
26 KiB
C
/*
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* Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Birrell.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <string.h>
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#ifdef _THREAD_SAFE
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#include <pthread.h>
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#include "pthread_private.h"
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#define FDQ_INSERT(q,p) \
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do { \
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TAILQ_INSERT_TAIL(q,p,qe); \
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p->flags |= PTHREAD_FLAGS_IN_FDQ; \
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} while (0)
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#define FDQ_REMOVE(q,p) \
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do { \
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if ((p->flags & PTHREAD_FLAGS_IN_FDQ) != 0) { \
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TAILQ_REMOVE(q,p,qe); \
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p->flags &= ~PTHREAD_FLAGS_IN_FDQ; \
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} \
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} while (0)
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/* Static variables: */
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static spinlock_t fd_table_lock = _SPINLOCK_INITIALIZER;
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/* Prototypes: */
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static inline pthread_t fd_next_reader(int fd);
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static inline pthread_t fd_next_writer(int fd);
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/*
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* This function *must* return -1 and set the thread specific errno
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* as a system call. This is because the error return from this
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* function is propagated directly back from thread-wrapped system
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* calls.
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*/
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int
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_thread_fd_table_init(int fd)
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{
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int ret = 0;
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struct fd_table_entry *entry;
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int saved_errno;
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/* Check if the file descriptor is out of range: */
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if (fd < 0 || fd >= _thread_dtablesize) {
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/* Return a bad file descriptor error: */
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errno = EBADF;
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ret = -1;
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}
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/*
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* Check if memory has already been allocated for this file
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* descriptor:
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*/
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else if (_thread_fd_table[fd] != NULL) {
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/* Memory has already been allocated. */
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/* Allocate memory for the file descriptor table entry: */
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} else if ((entry = (struct fd_table_entry *)
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malloc(sizeof(struct fd_table_entry))) == NULL) {
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/* Return an insufficient memory error: */
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errno = ENOMEM;
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ret = -1;
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} else {
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/* Initialise the file locks: */
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memset(&entry->lock, 0, sizeof(entry->lock));
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entry->r_owner = NULL;
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entry->w_owner = NULL;
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entry->r_fname = NULL;
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entry->w_fname = NULL;
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entry->r_lineno = 0;
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entry->w_lineno = 0;
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entry->r_lockcount = 0;
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entry->w_lockcount = 0;
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/* Initialise the read/write queues: */
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TAILQ_INIT(&entry->r_queue);
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TAILQ_INIT(&entry->w_queue);
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/* Get the flags for the file: */
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if (((fd >= 3) || (_pthread_stdio_flags[fd] == -1)) &&
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(entry->flags = _thread_sys_fcntl(fd, F_GETFL, 0)) == -1) {
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ret = -1;
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}
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else {
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/* Check if a stdio descriptor: */
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if ((fd < 3) && (_pthread_stdio_flags[fd] != -1))
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/*
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* Use the stdio flags read by
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* _pthread_init() to avoid
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* mistaking the non-blocking
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* flag that, when set on one
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* stdio fd, is set on all stdio
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* fds.
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*/
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entry->flags = _pthread_stdio_flags[fd];
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/*
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* Make the file descriptor non-blocking.
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* This might fail if the device driver does
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* not support non-blocking calls, or if the
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* driver is naturally non-blocking.
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*/
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saved_errno = errno;
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_thread_sys_fcntl(fd, F_SETFL,
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entry->flags | O_NONBLOCK);
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errno = saved_errno;
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/* Lock the file descriptor table: */
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_SPINLOCK(&fd_table_lock);
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/*
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* Check if another thread allocated the
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* file descriptor entry while this thread
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* was doing the same thing. The table wasn't
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* kept locked during this operation because
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* it has the potential to recurse.
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*/
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if (_thread_fd_table[fd] == NULL) {
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/* This thread wins: */
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_thread_fd_table[fd] = entry;
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entry = NULL;
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}
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/* Unlock the file descriptor table: */
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_SPINUNLOCK(&fd_table_lock);
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}
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/*
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* Check if another thread initialised the table entry
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* before this one could:
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*/
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if (entry != NULL)
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/*
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* Throw away the table entry that this thread
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* prepared. The other thread wins.
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*/
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free(entry);
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}
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/* Return the completion status: */
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return (ret);
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}
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void
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_thread_fd_unlock(int fd, int lock_type)
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{
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int ret;
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/*
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* Check that the file descriptor table is initialised for this
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* entry:
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*/
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if ((ret = _thread_fd_table_init(fd)) == 0) {
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/*
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* Defer signals to protect the scheduling queues from
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* access by the signal handler:
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*/
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_thread_kern_sig_defer();
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/*
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* Lock the file descriptor table entry to prevent
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* other threads for clashing with the current
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* thread's accesses:
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*/
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_SPINLOCK(&_thread_fd_table[fd]->lock);
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/* Check if the running thread owns the read lock: */
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if (_thread_fd_table[fd]->r_owner == _thread_run) {
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/* Check the file descriptor and lock types: */
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if (lock_type == FD_READ || lock_type == FD_RDWR) {
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/*
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* Decrement the read lock count for the
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* running thread:
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*/
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_thread_fd_table[fd]->r_lockcount--;
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/*
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* Check if the running thread still has read
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* locks on this file descriptor:
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*/
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if (_thread_fd_table[fd]->r_lockcount != 0) {
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}
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/*
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* Get the next thread in the queue for a
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* read lock on this file descriptor:
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*/
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else if ((_thread_fd_table[fd]->r_owner = fd_next_reader(fd)) == NULL) {
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} else {
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/* Remove this thread from the queue: */
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FDQ_REMOVE(&_thread_fd_table[fd]->r_queue,
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_thread_fd_table[fd]->r_owner);
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/*
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* Set the state of the new owner of
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* the thread to running:
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*/
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PTHREAD_NEW_STATE(_thread_fd_table[fd]->r_owner,PS_RUNNING);
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/*
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* Reset the number of read locks.
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* This will be incremented by the
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* new owner of the lock when it sees
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* that it has the lock.
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*/
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_thread_fd_table[fd]->r_lockcount = 0;
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}
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}
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}
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/* Check if the running thread owns the write lock: */
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if (_thread_fd_table[fd]->w_owner == _thread_run) {
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/* Check the file descriptor and lock types: */
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if (lock_type == FD_WRITE || lock_type == FD_RDWR) {
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/*
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* Decrement the write lock count for the
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* running thread:
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*/
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_thread_fd_table[fd]->w_lockcount--;
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/*
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* Check if the running thread still has
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* write locks on this file descriptor:
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*/
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if (_thread_fd_table[fd]->w_lockcount != 0) {
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}
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/*
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* Get the next thread in the queue for a
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* write lock on this file descriptor:
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*/
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else if ((_thread_fd_table[fd]->w_owner = fd_next_writer(fd)) == NULL) {
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} else {
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/* Remove this thread from the queue: */
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FDQ_REMOVE(&_thread_fd_table[fd]->w_queue,
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_thread_fd_table[fd]->w_owner);
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/*
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* Set the state of the new owner of
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* the thread to running:
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*/
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PTHREAD_NEW_STATE(_thread_fd_table[fd]->w_owner,PS_RUNNING);
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/*
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* Reset the number of write locks.
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* This will be incremented by the
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* new owner of the lock when it
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* sees that it has the lock.
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*/
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_thread_fd_table[fd]->w_lockcount = 0;
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}
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}
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}
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/* Unlock the file descriptor table entry: */
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_SPINUNLOCK(&_thread_fd_table[fd]->lock);
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/*
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* Undefer and handle pending signals, yielding if
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* necessary:
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*/
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_thread_kern_sig_undefer();
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}
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}
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int
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_thread_fd_lock(int fd, int lock_type, struct timespec * timeout)
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{
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int ret;
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/*
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* Check that the file descriptor table is initialised for this
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* entry:
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*/
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if ((ret = _thread_fd_table_init(fd)) == 0) {
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/* Clear the interrupted flag: */
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_thread_run->interrupted = 0;
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/*
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* Lock the file descriptor table entry to prevent
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* other threads for clashing with the current
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* thread's accesses:
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*/
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_SPINLOCK(&_thread_fd_table[fd]->lock);
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/* Check the file descriptor and lock types: */
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if (lock_type == FD_READ || lock_type == FD_RDWR) {
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/*
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* Wait for the file descriptor to be locked
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* for read for the current thread:
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*/
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while ((_thread_fd_table[fd]->r_owner != _thread_run) &&
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(_thread_run->interrupted == 0)) {
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/*
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* Check if the file descriptor is locked by
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* another thread:
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*/
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if (_thread_fd_table[fd]->r_owner != NULL) {
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/*
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* Another thread has locked the file
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* descriptor for read, so join the
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* queue of threads waiting for a
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* read lock on this file descriptor:
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*/
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FDQ_INSERT(&_thread_fd_table[fd]->r_queue, _thread_run);
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/*
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* Save the file descriptor details
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* in the thread structure for the
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* running thread:
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*/
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_thread_run->data.fd.fd = fd;
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/* Set the timeout: */
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_thread_kern_set_timeout(timeout);
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/*
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* Unlock the file descriptor
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* table entry:
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*/
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_SPINUNLOCK(&_thread_fd_table[fd]->lock);
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/*
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* Schedule this thread to wait on
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* the read lock. It will only be
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* woken when it becomes the next in
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* the queue and is granted access
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* to the lock by the thread
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* that is unlocking the file
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* descriptor.
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*/
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_thread_kern_sched_state(PS_FDLR_WAIT, __FILE__, __LINE__);
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/*
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* Lock the file descriptor
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* table entry again:
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*/
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_SPINLOCK(&_thread_fd_table[fd]->lock);
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if (_thread_run->interrupted != 0) {
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FDQ_REMOVE(&_thread_fd_table[fd]->r_queue,
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_thread_run);
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}
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} else {
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/*
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* The running thread now owns the
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* read lock on this file descriptor:
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*/
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_thread_fd_table[fd]->r_owner = _thread_run;
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/*
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* Reset the number of read locks for
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* this file descriptor:
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*/
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_thread_fd_table[fd]->r_lockcount = 0;
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}
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}
|
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if (_thread_fd_table[fd]->r_owner == _thread_run)
|
|
/* Increment the read lock count: */
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|
_thread_fd_table[fd]->r_lockcount++;
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}
|
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|
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/* Check the file descriptor and lock types: */
|
|
if (_thread_run->interrupted == 0 &&
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(lock_type == FD_WRITE || lock_type == FD_RDWR)) {
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/*
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* Wait for the file descriptor to be locked
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* for write for the current thread:
|
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*/
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while ((_thread_fd_table[fd]->w_owner != _thread_run) &&
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(_thread_run->interrupted == 0)) {
|
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/*
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* Check if the file descriptor is locked by
|
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* another thread:
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*/
|
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if (_thread_fd_table[fd]->w_owner != NULL) {
|
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/*
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* Another thread has locked the file
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* descriptor for write, so join the
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* queue of threads waiting for a
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* write lock on this file
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* descriptor:
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*/
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FDQ_INSERT(&_thread_fd_table[fd]->w_queue, _thread_run);
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|
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/*
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* Save the file descriptor details
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* in the thread structure for the
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* running thread:
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*/
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_thread_run->data.fd.fd = fd;
|
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|
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/* Set the timeout: */
|
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_thread_kern_set_timeout(timeout);
|
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|
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/*
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* Unlock the file descriptor
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* table entry:
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*/
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_SPINUNLOCK(&_thread_fd_table[fd]->lock);
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|
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/*
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* Schedule this thread to wait on
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* the write lock. It will only be
|
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* woken when it becomes the next in
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* the queue and is granted access to
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* the lock by the thread that is
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* unlocking the file descriptor.
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*/
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_thread_kern_sched_state(PS_FDLW_WAIT, __FILE__, __LINE__);
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|
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/*
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* Lock the file descriptor
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* table entry again:
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*/
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_SPINLOCK(&_thread_fd_table[fd]->lock);
|
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|
|
if (_thread_run->interrupted != 0) {
|
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FDQ_REMOVE(&_thread_fd_table[fd]->w_queue,
|
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_thread_run);
|
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}
|
|
} else {
|
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/*
|
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* The running thread now owns the
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* write lock on this file
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* descriptor:
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|
*/
|
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_thread_fd_table[fd]->w_owner = _thread_run;
|
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|
|
/*
|
|
* Reset the number of write locks
|
|
* for this file descriptor:
|
|
*/
|
|
_thread_fd_table[fd]->w_lockcount = 0;
|
|
}
|
|
}
|
|
|
|
if (_thread_fd_table[fd]->w_owner == _thread_run)
|
|
/* Increment the write lock count: */
|
|
_thread_fd_table[fd]->w_lockcount++;
|
|
}
|
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|
|
/* Unlock the file descriptor table entry: */
|
|
_SPINUNLOCK(&_thread_fd_table[fd]->lock);
|
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|
|
if (_thread_run->interrupted != 0) {
|
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ret = -1;
|
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errno = EINTR;
|
|
if (_thread_run->continuation != NULL)
|
|
_thread_run->continuation((void *)_thread_run);
|
|
}
|
|
}
|
|
|
|
/* Return the completion status: */
|
|
return (ret);
|
|
}
|
|
|
|
void
|
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_thread_fd_unlock_debug(int fd, int lock_type, char *fname, int lineno)
|
|
{
|
|
int ret;
|
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|
|
/*
|
|
* Check that the file descriptor table is initialised for this
|
|
* entry:
|
|
*/
|
|
if ((ret = _thread_fd_table_init(fd)) == 0) {
|
|
/*
|
|
* Defer signals to protect the scheduling queues from
|
|
* access by the signal handler:
|
|
*/
|
|
_thread_kern_sig_defer();
|
|
|
|
/*
|
|
* Lock the file descriptor table entry to prevent
|
|
* other threads for clashing with the current
|
|
* thread's accesses:
|
|
*/
|
|
_spinlock_debug(&_thread_fd_table[fd]->lock, fname, lineno);
|
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|
|
/* Check if the running thread owns the read lock: */
|
|
if (_thread_fd_table[fd]->r_owner == _thread_run) {
|
|
/* Check the file descriptor and lock types: */
|
|
if (lock_type == FD_READ || lock_type == FD_RDWR) {
|
|
/*
|
|
* Decrement the read lock count for the
|
|
* running thread:
|
|
*/
|
|
_thread_fd_table[fd]->r_lockcount--;
|
|
|
|
/*
|
|
* Check if the running thread still has read
|
|
* locks on this file descriptor:
|
|
*/
|
|
if (_thread_fd_table[fd]->r_lockcount != 0) {
|
|
}
|
|
/*
|
|
* Get the next thread in the queue for a
|
|
* read lock on this file descriptor:
|
|
*/
|
|
else if ((_thread_fd_table[fd]->r_owner = fd_next_reader(fd)) == NULL) {
|
|
} else {
|
|
/* Remove this thread from the queue: */
|
|
FDQ_REMOVE(&_thread_fd_table[fd]->r_queue,
|
|
_thread_fd_table[fd]->r_owner);
|
|
|
|
/*
|
|
* Set the state of the new owner of
|
|
* the thread to running:
|
|
*/
|
|
PTHREAD_NEW_STATE(_thread_fd_table[fd]->r_owner,PS_RUNNING);
|
|
|
|
/*
|
|
* Reset the number of read locks.
|
|
* This will be incremented by the
|
|
* new owner of the lock when it sees
|
|
* that it has the lock.
|
|
*/
|
|
_thread_fd_table[fd]->r_lockcount = 0;
|
|
}
|
|
}
|
|
}
|
|
/* Check if the running thread owns the write lock: */
|
|
if (_thread_fd_table[fd]->w_owner == _thread_run) {
|
|
/* Check the file descriptor and lock types: */
|
|
if (lock_type == FD_WRITE || lock_type == FD_RDWR) {
|
|
/*
|
|
* Decrement the write lock count for the
|
|
* running thread:
|
|
*/
|
|
_thread_fd_table[fd]->w_lockcount--;
|
|
|
|
/*
|
|
* Check if the running thread still has
|
|
* write locks on this file descriptor:
|
|
*/
|
|
if (_thread_fd_table[fd]->w_lockcount != 0) {
|
|
}
|
|
/*
|
|
* Get the next thread in the queue for a
|
|
* write lock on this file descriptor:
|
|
*/
|
|
else if ((_thread_fd_table[fd]->w_owner = fd_next_writer(fd)) == NULL) {
|
|
} else {
|
|
/* Remove this thread from the queue: */
|
|
FDQ_REMOVE(&_thread_fd_table[fd]->w_queue,
|
|
_thread_fd_table[fd]->w_owner);
|
|
|
|
/*
|
|
* Set the state of the new owner of
|
|
* the thread to running:
|
|
*/
|
|
PTHREAD_NEW_STATE(_thread_fd_table[fd]->w_owner,PS_RUNNING);
|
|
|
|
/*
|
|
* Reset the number of write locks.
|
|
* This will be incremented by the
|
|
* new owner of the lock when it
|
|
* sees that it has the lock.
|
|
*/
|
|
_thread_fd_table[fd]->w_lockcount = 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Unlock the file descriptor table entry: */
|
|
_SPINUNLOCK(&_thread_fd_table[fd]->lock);
|
|
|
|
/*
|
|
* Undefer and handle pending signals, yielding if
|
|
* necessary.
|
|
*/
|
|
_thread_kern_sig_undefer();
|
|
}
|
|
}
|
|
|
|
int
|
|
_thread_fd_lock_debug(int fd, int lock_type, struct timespec * timeout,
|
|
char *fname, int lineno)
|
|
{
|
|
int ret;
|
|
|
|
/*
|
|
* Check that the file descriptor table is initialised for this
|
|
* entry:
|
|
*/
|
|
if ((ret = _thread_fd_table_init(fd)) == 0) {
|
|
/* Clear the interrupted flag: */
|
|
_thread_run->interrupted = 0;
|
|
|
|
/*
|
|
* Lock the file descriptor table entry to prevent
|
|
* other threads for clashing with the current
|
|
* thread's accesses:
|
|
*/
|
|
_spinlock_debug(&_thread_fd_table[fd]->lock, fname, lineno);
|
|
|
|
/* Check the file descriptor and lock types: */
|
|
if (lock_type == FD_READ || lock_type == FD_RDWR) {
|
|
/*
|
|
* Wait for the file descriptor to be locked
|
|
* for read for the current thread:
|
|
*/
|
|
while ((_thread_fd_table[fd]->r_owner != _thread_run) &&
|
|
(_thread_run->interrupted == 0)) {
|
|
/*
|
|
* Check if the file descriptor is locked by
|
|
* another thread:
|
|
*/
|
|
if (_thread_fd_table[fd]->r_owner != NULL) {
|
|
/*
|
|
* Another thread has locked the file
|
|
* descriptor for read, so join the
|
|
* queue of threads waiting for a
|
|
* read lock on this file descriptor:
|
|
*/
|
|
FDQ_INSERT(&_thread_fd_table[fd]->r_queue, _thread_run);
|
|
|
|
/*
|
|
* Save the file descriptor details
|
|
* in the thread structure for the
|
|
* running thread:
|
|
*/
|
|
_thread_run->data.fd.fd = fd;
|
|
_thread_run->data.fd.branch = lineno;
|
|
_thread_run->data.fd.fname = fname;
|
|
|
|
/* Set the timeout: */
|
|
_thread_kern_set_timeout(timeout);
|
|
|
|
/*
|
|
* Unlock the file descriptor
|
|
* table entry:
|
|
*/
|
|
_SPINUNLOCK(&_thread_fd_table[fd]->lock);
|
|
|
|
/*
|
|
* Schedule this thread to wait on
|
|
* the read lock. It will only be
|
|
* woken when it becomes the next in
|
|
* the queue and is granted access
|
|
* to the lock by the thread
|
|
* that is unlocking the file
|
|
* descriptor.
|
|
*/
|
|
_thread_kern_sched_state(PS_FDLR_WAIT, __FILE__, __LINE__);
|
|
|
|
/*
|
|
* Lock the file descriptor
|
|
* table entry again:
|
|
*/
|
|
_SPINLOCK(&_thread_fd_table[fd]->lock);
|
|
|
|
if (_thread_run->interrupted != 0) {
|
|
FDQ_REMOVE(&_thread_fd_table[fd]->r_queue,
|
|
_thread_run);
|
|
}
|
|
} else {
|
|
/*
|
|
* The running thread now owns the
|
|
* read lock on this file descriptor:
|
|
*/
|
|
_thread_fd_table[fd]->r_owner = _thread_run;
|
|
|
|
/*
|
|
* Reset the number of read locks for
|
|
* this file descriptor:
|
|
*/
|
|
_thread_fd_table[fd]->r_lockcount = 0;
|
|
|
|
/*
|
|
* Save the source file details for
|
|
* debugging:
|
|
*/
|
|
_thread_fd_table[fd]->r_fname = fname;
|
|
_thread_fd_table[fd]->r_lineno = lineno;
|
|
}
|
|
}
|
|
|
|
if (_thread_fd_table[fd]->r_owner == _thread_run)
|
|
/* Increment the read lock count: */
|
|
_thread_fd_table[fd]->r_lockcount++;
|
|
}
|
|
|
|
/* Check the file descriptor and lock types: */
|
|
if (_thread_run->interrupted == 0 &&
|
|
(lock_type == FD_WRITE || lock_type == FD_RDWR)) {
|
|
/*
|
|
* Wait for the file descriptor to be locked
|
|
* for write for the current thread:
|
|
*/
|
|
while ((_thread_fd_table[fd]->w_owner != _thread_run) &&
|
|
(_thread_run->interrupted == 0)) {
|
|
/*
|
|
* Check if the file descriptor is locked by
|
|
* another thread:
|
|
*/
|
|
if (_thread_fd_table[fd]->w_owner != NULL) {
|
|
/*
|
|
* Another thread has locked the file
|
|
* descriptor for write, so join the
|
|
* queue of threads waiting for a
|
|
* write lock on this file
|
|
* descriptor:
|
|
*/
|
|
FDQ_INSERT(&_thread_fd_table[fd]->w_queue, _thread_run);
|
|
|
|
/*
|
|
* Save the file descriptor details
|
|
* in the thread structure for the
|
|
* running thread:
|
|
*/
|
|
_thread_run->data.fd.fd = fd;
|
|
_thread_run->data.fd.branch = lineno;
|
|
_thread_run->data.fd.fname = fname;
|
|
|
|
/* Set the timeout: */
|
|
_thread_kern_set_timeout(timeout);
|
|
|
|
/*
|
|
* Unlock the file descriptor
|
|
* table entry:
|
|
*/
|
|
_SPINUNLOCK(&_thread_fd_table[fd]->lock);
|
|
|
|
/*
|
|
* Schedule this thread to wait on
|
|
* the write lock. It will only be
|
|
* woken when it becomes the next in
|
|
* the queue and is granted access to
|
|
* the lock by the thread that is
|
|
* unlocking the file descriptor.
|
|
*/
|
|
_thread_kern_sched_state(PS_FDLW_WAIT, __FILE__, __LINE__);
|
|
|
|
/*
|
|
* Lock the file descriptor
|
|
* table entry again:
|
|
*/
|
|
_SPINLOCK(&_thread_fd_table[fd]->lock);
|
|
|
|
if (_thread_run->interrupted != 0) {
|
|
FDQ_REMOVE(&_thread_fd_table[fd]->w_queue,
|
|
_thread_run);
|
|
}
|
|
} else {
|
|
/*
|
|
* The running thread now owns the
|
|
* write lock on this file
|
|
* descriptor:
|
|
*/
|
|
_thread_fd_table[fd]->w_owner = _thread_run;
|
|
|
|
/*
|
|
* Reset the number of write locks
|
|
* for this file descriptor:
|
|
*/
|
|
_thread_fd_table[fd]->w_lockcount = 0;
|
|
|
|
/*
|
|
* Save the source file details for
|
|
* debugging:
|
|
*/
|
|
_thread_fd_table[fd]->w_fname = fname;
|
|
_thread_fd_table[fd]->w_lineno = lineno;
|
|
}
|
|
}
|
|
|
|
if (_thread_fd_table[fd]->w_owner == _thread_run)
|
|
/* Increment the write lock count: */
|
|
_thread_fd_table[fd]->w_lockcount++;
|
|
}
|
|
|
|
/* Unlock the file descriptor table entry: */
|
|
_SPINUNLOCK(&_thread_fd_table[fd]->lock);
|
|
|
|
if (_thread_run->interrupted != 0) {
|
|
ret = -1;
|
|
errno = EINTR;
|
|
if (_thread_run->continuation != NULL)
|
|
_thread_run->continuation((void *)_thread_run);
|
|
}
|
|
}
|
|
|
|
/* Return the completion status: */
|
|
return (ret);
|
|
}
|
|
|
|
void
|
|
_thread_fd_unlock_owned(pthread_t pthread)
|
|
{
|
|
int fd;
|
|
|
|
for (fd = 0; fd < _thread_dtablesize; fd++) {
|
|
if ((_thread_fd_table[fd] != NULL) &&
|
|
((_thread_fd_table[fd]->r_owner == pthread) ||
|
|
(_thread_fd_table[fd]->w_owner == pthread))) {
|
|
/*
|
|
* Defer signals to protect the scheduling queues
|
|
* from access by the signal handler:
|
|
*/
|
|
_thread_kern_sig_defer();
|
|
|
|
/*
|
|
* Lock the file descriptor table entry to prevent
|
|
* other threads for clashing with the current
|
|
* thread's accesses:
|
|
*/
|
|
_SPINLOCK(&_thread_fd_table[fd]->lock);
|
|
|
|
/* Check if the thread owns the read lock: */
|
|
if (_thread_fd_table[fd]->r_owner == pthread) {
|
|
/* Clear the read lock count: */
|
|
_thread_fd_table[fd]->r_lockcount = 0;
|
|
|
|
/*
|
|
* Get the next thread in the queue for a
|
|
* read lock on this file descriptor:
|
|
*/
|
|
if ((_thread_fd_table[fd]->r_owner = fd_next_reader(fd)) != NULL) {
|
|
/* Remove this thread from the queue: */
|
|
FDQ_REMOVE(&_thread_fd_table[fd]->r_queue,
|
|
_thread_fd_table[fd]->r_owner);
|
|
|
|
/*
|
|
* Set the state of the new owner of
|
|
* the thread to running:
|
|
*/
|
|
PTHREAD_NEW_STATE(_thread_fd_table[fd]->r_owner,PS_RUNNING);
|
|
}
|
|
}
|
|
|
|
/* Check if the thread owns the write lock: */
|
|
if (_thread_fd_table[fd]->w_owner == pthread) {
|
|
/* Clear the write lock count: */
|
|
_thread_fd_table[fd]->w_lockcount = 0;
|
|
|
|
/*
|
|
* Get the next thread in the queue for a
|
|
* write lock on this file descriptor:
|
|
*/
|
|
if ((_thread_fd_table[fd]->w_owner = fd_next_writer(fd)) != NULL) {
|
|
/* Remove this thread from the queue: */
|
|
FDQ_REMOVE(&_thread_fd_table[fd]->w_queue,
|
|
_thread_fd_table[fd]->w_owner);
|
|
|
|
/*
|
|
* Set the state of the new owner of
|
|
* the thread to running:
|
|
*/
|
|
PTHREAD_NEW_STATE(_thread_fd_table[fd]->w_owner,PS_RUNNING);
|
|
|
|
}
|
|
}
|
|
|
|
/* Unlock the file descriptor table entry: */
|
|
_SPINUNLOCK(&_thread_fd_table[fd]->lock);
|
|
|
|
/*
|
|
* Undefer and handle pending signals, yielding if
|
|
* necessary.
|
|
*/
|
|
_thread_kern_sig_undefer();
|
|
}
|
|
}
|
|
}
|
|
|
|
void
|
|
_fd_lock_backout(pthread_t pthread)
|
|
{
|
|
int fd;
|
|
|
|
/*
|
|
* Defer signals to protect the scheduling queues
|
|
* from access by the signal handler:
|
|
*/
|
|
_thread_kern_sig_defer();
|
|
|
|
switch (pthread->state) {
|
|
|
|
case PS_FDLR_WAIT:
|
|
fd = pthread->data.fd.fd;
|
|
|
|
/*
|
|
* Lock the file descriptor table entry to prevent
|
|
* other threads for clashing with the current
|
|
* thread's accesses:
|
|
*/
|
|
_SPINLOCK(&_thread_fd_table[fd]->lock);
|
|
|
|
/* Remove the thread from the waiting queue: */
|
|
FDQ_REMOVE(&_thread_fd_table[fd]->r_queue, pthread);
|
|
break;
|
|
|
|
case PS_FDLW_WAIT:
|
|
fd = pthread->data.fd.fd;
|
|
|
|
/*
|
|
* Lock the file descriptor table entry to prevent
|
|
* other threads from clashing with the current
|
|
* thread's accesses:
|
|
*/
|
|
_SPINLOCK(&_thread_fd_table[fd]->lock);
|
|
|
|
/* Remove the thread from the waiting queue: */
|
|
FDQ_REMOVE(&_thread_fd_table[fd]->w_queue, pthread);
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Undefer and handle pending signals, yielding if
|
|
* necessary.
|
|
*/
|
|
_thread_kern_sig_undefer();
|
|
}
|
|
|
|
static inline pthread_t
|
|
fd_next_reader(int fd)
|
|
{
|
|
pthread_t pthread;
|
|
|
|
while (((pthread = TAILQ_FIRST(&_thread_fd_table[fd]->r_queue)) != NULL) &&
|
|
(pthread->interrupted != 0)) {
|
|
/*
|
|
* This thread has either been interrupted by a signal or
|
|
* it has been canceled. Remove it from the queue.
|
|
*/
|
|
FDQ_REMOVE(&_thread_fd_table[fd]->r_queue, pthread);
|
|
}
|
|
|
|
return (pthread);
|
|
}
|
|
|
|
static inline pthread_t
|
|
fd_next_writer(int fd)
|
|
{
|
|
pthread_t pthread;
|
|
|
|
while (((pthread = TAILQ_FIRST(&_thread_fd_table[fd]->w_queue)) != NULL) &&
|
|
(pthread->interrupted != 0)) {
|
|
/*
|
|
* This thread has either been interrupted by a signal or
|
|
* it has been canceled. Remove it from the queue.
|
|
*/
|
|
FDQ_REMOVE(&_thread_fd_table[fd]->w_queue, pthread);
|
|
}
|
|
|
|
return (pthread);
|
|
}
|
|
#endif
|