Ridiculous amount of work for OpenBSD.

src/libthread/BSD.c

@@ -396,13 +396,6 @@ _threadsetproc(Proc *p)
 		pp->pid = -1;
 }
 
-void
-_pthreadinit(void)
-{
-	__isthreaded = 1;
-	signal(SIGUSR2, sigusr2handler);
-}
-
 void
 _threadpexit(void)
 {

src/libthread/FreeBSD.c

@@ -41,3 +41,9 @@ swapcontext(ucontext_t *oucp, ucontext_t *ucp)
 	return 0;
 }
 
+void
+_pthreadinit(void)
+{
+	__isthreaded = 1;
+	signal(SIGUSR2, sigusr2handler);
+}

src/libthread/OpenBSD.c

@@ -1,8 +1,32 @@
 #include "threadimpl.h"
-
 #include "BSD.c"
 
-static spinlock_t mlock = { 0, 0, NULL, 0 };
+#include <dlfcn.h>
+
+#define MIN(a,b)	((a) < (b) ? (a) : (b))
+#define MAX(a,b)	((a) > (b) ? (a) : (b))
+
+enum {
+	FD_READ = 1,
+	FD_WRITE,
+	FD_RDWR,
+	FDTBL_MAXSIZE = 128
+};
+
+struct fd_entry {
+	QLock	lock;
+	int	fd;
+	int	id;
+	short	rc;
+	short	wc;
+	short	ref;
+};
+
+static struct fd_entry fd_entry1 = { .fd -1 };
+static struct fd_entry *fd_table = nil;
+static spinlock_t fd_table_lock = { 0, 0, nil, 0 };
+static spinlock_t mlock = { 0, 0, nil, 0 };
+static spinlock_t dl_lock = { 0, 0, nil, 0 };
 
 void
 _thread_malloc_lock(void)
@@ -20,3 +44,139 @@ void
 _thread_malloc_init(void)
 {
 }
+
+/*
+ * Must set errno on failure because the return value
+ * of _thread_fd_entry is propagated back to the caller
+ * of the thread-wrapped libc function.
+ */
+static struct fd_entry *
+_thread_fd_lookup(int fd)
+{
+	struct fd_entry *t;
+	static int cursize;
+	int newsize;
+
+	if(fd >= FDTBL_MAXSIZE) {
+		errno = EBADF;
+		return nil;
+	}
+
+	/*
+	 * There are currently only a few libc functions using 
+	 * _thread_fd_*, which are rarely called by P9P programs.
+	 * So the contention for these locks is very small and so
+	 * far have usually been limited to a single fd. So
+	 * rather than malloc the fd_table everytime we just use
+	 * a single fd_entry until a lock request for another fd
+	 * comes in.
+	 */
+	if(fd_table == nil)
+		if(fd_entry1.fd == -1) {
+			fd_entry1.fd = fd;
+			return &fd_entry1;
+		} else if(fd_entry1.fd == fd)
+			return &fd_entry1;
+		else {
+			cursize = MAX(fd_entry1.fd, 16);
+			fd_table = malloc(cursize*sizeof(fd_table[0]));
+			if(fd_table == nil) {
+				errno = ENOMEM;
+				return nil;
+			}
+			memset(fd_table, 0, cursize*sizeof(fd_table[0]));
+			fd_table[fd_entry1.fd] = fd_entry1;
+		}
+	if(fd > cursize) {
+		newsize = MIN(cursize*2, FDTBL_MAXSIZE);
+		t = realloc(fd_table, newsize*sizeof(fd_table[0]));
+		if(t == nil) {
+			errno = ENOMEM;
+			return nil;
+		}
+		fd_table = t;
+		cursize = newsize; 
+		memset(fd_table, 0, cursize*sizeof(fd_table[0]));
+	}
+
+	return &fd_table[fd];
+}
+
+/*
+ * Mutiple readers just share the lock by incrementing the read count.
+ * Writers must obtain an exclusive lock.
+ */
+int
+_thread_fd_lock(int fd, int type, struct timespec *time)
+{
+	struct fd_entry *fde;
+	int id;
+
+	_spinlock(&fd_table_lock);
+	fde = _thread_fd_lookup(fd);
+	if(fde == nil)
+		return -1;
+
+	if(type == FD_READ) {
+		if(fde->rc++ >= 1 && fde->wc == 0) {
+			_spinunlock(&fd_table_lock);
+			return 0;
+		}
+	} else
+		fde->wc++;
+	_spinunlock(&fd_table_lock);
+
+	/* handle recursion */
+	id = proc()->osprocid;
+	if(id == fde->id) {
+		fde->ref++;
+		return 0;
+	}
+
+	qlock(&fde->lock);
+	fde->id = id;
+	return 0;
+}
+
+void
+_thread_fd_unlock(int fd, int type)
+{
+	struct fd_entry *fde;
+	int id;
+
+	fde = _thread_fd_lookup(fd);
+	if(fde == nil) {
+		fprint(2, "_thread_fd_unlock: fd %d not in table!\n", fd);
+		return;
+	}
+
+	if(type == FD_READ && --fde->rc >= 1)
+		return;
+	else
+		fde->wc--;
+
+	id = proc()->osprocid;
+	if(id == fde->id && fde->ref > 0) {
+		fde->ref--;
+		return;
+	}
+	fde->id = 0;
+	qunlock(&fde->lock);
+}
+
+void
+_thread_dl_lock(int t)
+{
+	if(t)
+		_spinunlock(&dl_lock);
+	else
+		_spinlock(&dl_lock);
+}
+
+void
+_pthreadinit(void)
+{
+	__isthreaded = 1;
+	dlctl(nil, DL_SETTHREADLCK, _thread_dl_lock);
+	signal(SIGUSR2, sigusr2handler);
+}