Make _thread_suspend work with both the old broken sigtimedwait

implementation and the new improved one.  We now precompute the
signal set passed to sigtimedwait, using an inverted set when
necessary for compatibility with older kernels.

3 files changed, 31 insertions, 11 deletions

diff --git a/lib/libthr/thread/thr_init.c b/lib/libthr/thread/thr_init.c
index c404651..671bd6f 100644
--- a/lib/libthr/thread/thr_init.c
+++ b/lib/libthr/thread/thr_init.c
@@ -66,6 +66,14 @@
 
 #include "thr_private.h"
 
+/*
+ * Early implementations of sigtimedwait interpreted the signal
+ * set incorrectly.
+ */
+#define SIGTIMEDWAIT_SET_IS_INVERTED(osreldate) \
+    ((500100 <= (osreldate) && (osreldate) <= 500113) || \
+    (osreldate) == 501000 || (osreldate) == 501100)
+
 extern void _thread_init_hack(void);
 
 /*
@@ -168,6 +176,7 @@ _thread_init(void)
 	size_t		len;
 	int		mib[2];
 	sigset_t	set;
+	int		osreldate;
 	int		error;
 
 	struct clockinfo clockinfo;
@@ -324,6 +333,23 @@ _thread_init(void)
 	SIGADDSET(set, SIGTHR);
 	__sys_sigprocmask(SIG_BLOCK, &set, 0);
 
+	/*
+	 * Precompute the signal set used by _thread_suspend to wait
+	 * for SIGTHR.
+	 */
+	mib[0] = CTL_KERN;
+	mib[1] = KERN_OSRELDATE;
+	len = sizeof(osreldate);
+	if (sysctl(mib, 2, &osreldate, &len, NULL, 0) == 0 &&
+	    SIGTIMEDWAIT_SET_IS_INVERTED(osreldate)) {
+		/* Kernel bug requires an inverted signal set. */
+		SIGFILLSET(_thread_suspend_sigset);
+		SIGDELSET(_thread_suspend_sigset, SIGTHR);
+	} else {
+		SIGEMPTYSET(_thread_suspend_sigset);
+		SIGADDSET(_thread_suspend_sigset, SIGTHR);
+	}
+
 	/* Get the kernel clockrate: */
 	mib[0] = CTL_KERN;
 	mib[1] = KERN_CLOCKRATE;
diff --git a/lib/libthr/thread/thr_kern.c b/lib/libthr/thread/thr_kern.c
index 1c9a8ce..f45cae5 100644
--- a/lib/libthr/thread/thr_kern.c
+++ b/lib/libthr/thread/thr_kern.c
@@ -179,16 +179,9 @@ _thread_suspend(pthread_t pthread, struct timespec *abstime)
 	struct timespec remaining;
 	struct timespec *ts;
 	siginfo_t info;
-	sigset_t set;
 	int error;
 
 	/*
-	 * Catch SIGTHR.
-	 */
-	SIGFILLSET(set);
-	SIGDELSET(set, SIGTHR);
-
-	/*
 	 * Compute the remainder of the run time.
 	 */
 	if (abstime) {
@@ -204,9 +197,7 @@ _thread_suspend(pthread_t pthread, struct timespec *abstime)
 	} else
 		ts = NULL;
 
-	error = sigtimedwait(&set, &info, ts);
-	if (error == -1)
-		error = errno;
-
+	error = sigtimedwait(&_thread_suspend_sigset, &info, ts);
+	error = (error == -1) ? errno : 0;
 	return (error);
 }
diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_private.h
index 9989342..b273890 100644
--- a/lib/libthr/thread/thr_private.h
+++ b/lib/libthr/thread/thr_private.h
@@ -692,6 +692,9 @@ SCLASS	pthread_cond_t  _gc_cond
  */
 SCLASS struct  sigaction _thread_sigact[NSIG];
 
+/* Precomputed signal set for _thread_suspend. */
+SCLASS sigset_t _thread_suspend_sigset;
+
 /* Tracks the number of threads blocked while waiting for a spinlock. */
 SCLASS	volatile int	_spinblock_count
 #ifdef GLOBAL_PTHREAD_PRIVATE