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authordeischen <deischen@FreeBSD.org>2000-10-13 22:12:32 +0000
committerdeischen <deischen@FreeBSD.org>2000-10-13 22:12:32 +0000
commit4e7266f9876e7fe6b1db79714ce85bc5f3c00277 (patch)
treeae8f1872fb399eacfefbc5a2c1c375c874327a09 /lib/libpthread/thread/thr_exit.c
parent203b4ae935cb0ac4e62b1018a6386f5b919abae2 (diff)
downloadFreeBSD-src-4e7266f9876e7fe6b1db79714ce85bc5f3c00277.zip
FreeBSD-src-4e7266f9876e7fe6b1db79714ce85bc5f3c00277.tar.gz
Implement zero system call thread switching. Performance of
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
Diffstat (limited to 'lib/libpthread/thread/thr_exit.c')
-rw-r--r--lib/libpthread/thread/thr_exit.c80
1 files changed, 41 insertions, 39 deletions
diff --git a/lib/libpthread/thread/thr_exit.c b/lib/libpthread/thread/thr_exit.c
index 0d22638..7fbeb65 100644
--- a/lib/libpthread/thread/thr_exit.c
+++ b/lib/libpthread/thread/thr_exit.c
@@ -41,6 +41,9 @@
#include <pthread.h>
#include "pthread_private.h"
+#define FLAGS_IN_SCHEDQ \
+ (PTHREAD_FLAGS_IN_PRIOQ|PTHREAD_FLAGS_IN_WAITQ|PTHREAD_FLAGS_IN_WORKQ)
+
void __exit(int status)
{
int flags;
@@ -138,7 +141,7 @@ _thread_exit_cleanup(void)
void
pthread_exit(void *status)
{
- pthread_t pthread;
+ int frame;
/* Check if this thread is already in the process of exiting: */
if ((_thread_run->flags & PTHREAD_EXITING) != 0) {
@@ -172,25 +175,24 @@ pthread_exit(void *status)
_thread_run->poll_data.fds = NULL;
}
- /*
- * Defer signals to protect the scheduling queues from access
- * by the signal handler:
- */
- _thread_kern_sig_defer();
-
- /* Check if there are any threads joined to this one: */
- while ((pthread = TAILQ_FIRST(&(_thread_run->join_queue))) != NULL) {
- /* Remove the thread from the queue: */
- TAILQ_REMOVE(&_thread_run->join_queue, pthread, qe);
-
- /* Wake the joined thread and let it detach this thread: */
- PTHREAD_NEW_STATE(pthread,PS_RUNNING);
+ if ((frame = _thread_run->sigframe_count) == 0)
+ _thread_exit_finish();
+ else {
+ /*
+ * Jump back and unwind the signal frames to gracefully
+ * cleanup.
+ */
+ ___longjmp(*_thread_run->sigframes[frame]->sig_jb, 1);
}
- /*
- * Undefer and handle pending signals, yielding if necessary:
- */
- _thread_kern_sig_undefer();
+ /* This point should not be reached. */
+ PANIC("Dead thread has resumed");
+}
+
+void
+_thread_exit_finish(void)
+{
+ pthread_t pthread;
/*
* Lock the garbage collector mutex to ensure that the garbage
@@ -203,20 +205,6 @@ pthread_exit(void *status)
TAILQ_INSERT_HEAD(&_dead_list, _thread_run, dle);
/*
- * Defer signals to protect the scheduling queues from access
- * by the signal handler:
- */
- _thread_kern_sig_defer();
-
- /* Remove this thread from the thread list: */
- TAILQ_REMOVE(&_thread_list, _thread_run, tle);
-
- /*
- * Undefer and handle pending signals, yielding if necessary:
- */
- _thread_kern_sig_undefer();
-
- /*
* Signal the garbage collector thread that there is something
* to clean up.
*/
@@ -224,19 +212,33 @@ pthread_exit(void *status)
PANIC("Cannot signal gc cond");
/*
- * Mark the thread as dead so it will not return if it
- * gets context switched out when the mutex is unlocked.
+ * Avoid a race condition where a scheduling signal can occur
+ * causing the garbage collector thread to run. If this happens,
+ * the current thread can be cleaned out from under us.
*/
- PTHREAD_SET_STATE(_thread_run, PS_DEAD);
+ _thread_kern_sig_defer();
/* Unlock the garbage collector mutex: */
if (pthread_mutex_unlock(&_gc_mutex) != 0)
PANIC("Cannot lock gc mutex");
- /* This this thread will never be re-scheduled. */
- _thread_kern_sched(NULL);
+ /* Check if there are any threads joined to this one: */
+ while ((pthread = TAILQ_FIRST(&(_thread_run->join_queue))) != NULL) {
+ /* Remove the thread from the queue: */
+ TAILQ_REMOVE(&_thread_run->join_queue, pthread, sqe);
+ pthread->flags &= ~PTHREAD_FLAGS_IN_JOINQ;
+
+ /*
+ * Wake the joined thread and let it
+ * detach this thread:
+ */
+ PTHREAD_NEW_STATE(pthread, PS_RUNNING);
+ }
- /* This point should not be reached. */
- PANIC("Dead thread has resumed");
+ /* Remove this thread from the thread list: */
+ TAILQ_REMOVE(&_thread_list, _thread_run, tle);
+
+ /* This thread will never be re-scheduled. */
+ _thread_kern_sched_state(PS_DEAD, __FILE__, __LINE__);
}
#endif
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