Add a working pthread_[gs]etconcurrency. Initial null implementation

provided by Sergey A. Osokin <osa@freebsd.org.ru>.

In order to test this on a single CPU machine, you need to:

    sysctl kern.threads.debug=1
    sysctl kern.threads.virtual_cpu=2

2 files changed, 121 insertions, 0 deletions

diff --git a/lib/libpthread/thread/Makefile.inc b/lib/libpthread/thread/Makefile.inc
index 6b00117..ac7c844 100644
--- a/lib/libpthread/thread/Makefile.inc
+++ b/lib/libpthread/thread/Makefile.inc
@@ -31,6 +31,7 @@ SRCS+= \
 	thr_cancel.c \
 	thr_clean.c \
 	thr_close.c \
+	thr_concurrency.c \
 	thr_cond.c \
 	thr_condattr_destroy.c \
 	thr_condattr_init.c \
diff --git a/lib/libpthread/thread/thr_concurrency.c b/lib/libpthread/thread/thr_concurrency.c
new file mode 100644
index 0000000..a4b055f
--- /dev/null
+++ b/lib/libpthread/thread/thr_concurrency.c
@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2003 Daniel M. Eischen <deischen@freebsd.org>
+ * Copyright (c) 2003 Sergey Osokin <osa@freebsd.org.ru>.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Neither the name of the author nor the names of any co-contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+#include <errno.h>
+#include <pthread.h>
+
+#include "thr_private.h"
+
+/*#define DEBUG_CONCURRENCY */
+#ifdef DEBUG_CONCURRENCY
+#define DBG_MSG		stdout_debug
+#else
+#define	DBG_MSG(x...)
+#endif
+
+static int level = 0;
+
+__weak_reference(_pthread_getconcurrency, pthread_getconcurrency);
+__weak_reference(_pthread_setconcurrency, pthread_setconcurrency);
+
+int
+_pthread_getconcurrency(void)
+{
+	return (level);
+}
+
+int
+_pthread_setconcurrency(int new_level)
+{
+	struct pthread *curthread;
+	struct kse *newkse;
+	kse_critical_t crit;
+	int kse_count;
+	int i;
+	int ret;
+
+
+	if (new_level < 0)
+		ret = EINVAL;
+	else if (new_level == level)
+		ret = 0;
+	else if (new_level == 0) {
+		level = 0;
+		ret = 0;
+	} else if ((_kse_isthreaded() == 0) && (_kse_setthreaded(1) != 0)) {
+		DBG_MSG("Can't enable threading.\n");
+		ret = EAGAIN;
+	} else {
+		ret = 0;
+		curthread = _get_curthread();
+		/* Race condition, but so what. */
+		kse_count = _kse_initial->k_kseg->kg_ksecount;
+		for (i = kse_count; i < new_level; i++) {
+			newkse = _kse_alloc(curthread);
+			if (newkse == NULL) {
+				DBG_MSG("Can't alloc new KSE.\n");
+				ret = EAGAIN;
+				break;
+			}
+			newkse->k_kseg = _kse_initial->k_kseg;
+			newkse->k_schedq = _kse_initial->k_schedq;
+			newkse->k_curthread = NULL;
+			crit = _kse_critical_enter();
+			KSE_SCHED_LOCK(curthread->kse, newkse->k_kseg);
+			TAILQ_INSERT_TAIL(&newkse->k_kseg->kg_kseq,
+			    newkse, k_kgqe);
+			newkse->k_kseg->kg_ksecount++;
+			KSE_SCHED_UNLOCK(curthread->kse, newkse->k_kseg);
+			if (_ksd_setprivate(&_kse_initial->k_ksd) != 0) {
+				/* This should never happen. */
+				PANIC("pthread_setconcurrency: Unable to "
+				    "set KSE specific data");
+			}
+			newkse->k_flags |= KF_INITIALIZED;
+			if (kse_create(&newkse->k_mbx, 0) != 0) {
+				_ksd_setprivate(&curthread->kse->k_ksd);
+				KSE_SCHED_LOCK(curthread->kse, newkse->k_kseg);
+				TAILQ_REMOVE(&newkse->k_kseg->kg_kseq,
+				    newkse, k_kgqe);
+				newkse->k_kseg->kg_ksecount--;
+				KSE_SCHED_UNLOCK(curthread->kse, newkse->k_kseg);
+				_kse_critical_leave(crit);
+				_kse_free(curthread, newkse);
+				DBG_MSG("kse_create syscall failed.\n");
+				ret = EAGAIN;
+				break;
+			}
+			_ksd_setprivate(&curthread->kse->k_ksd);
+			_kse_critical_leave(crit);
+		}
+		if (ret == 0)
+			level = new_level;
+	}
+	return (ret);
+}