From 22a81fc246efb2668eddcb6ccd27129feaa5910c Mon Sep 17 00:00:00 2001
From: davidxu <davidxu@FreeBSD.org>
Date: Mon, 4 Dec 2006 14:15:12 +0000
Subject: if a thread blocked on userland condition variable is
 pthread_cancel()ed, it is expected that the thread will not consume a
 pthread_cond_signal(), therefor, we use thr_wake() to mark a flag, the flag
 tells a thread calling do_cv_wait() in umtx code to not block on a condition
 variable. Thread library is expected that once a thread detected itself is in
 pthread_cond_wait, it will call the thr_wake() for itself in its SIGCANCEL
 handler.

---
 sys/kern/kern_thr.c  | 11 +++++++++++
 sys/kern/kern_umtx.c | 15 ++++++++++-----
 sys/sys/proc.h       |  1 +
 sys/sys/umtx.h       |  3 +++
 4 files changed, 25 insertions(+), 5 deletions(-)

(limited to 'sys')

diff --git a/sys/kern/kern_thr.c b/sys/kern/kern_thr.c
index 29c7614..37e3df2 100644
--- a/sys/kern/kern_thr.c
+++ b/sys/kern/kern_thr.c
@@ -402,6 +402,12 @@ kern_thr_suspend(struct thread *td, struct timespec *tsp)
 		TIMESPEC_TO_TIMEVAL(&tv, tsp);
 		hz = tvtohz(&tv);
 	}
+
+	if (td->td_pflags & TDP_WAKEUP) {
+		td->td_pflags &= ~TDP_WAKEUP;
+		return (0);
+	}
+
 	PROC_LOCK(td->td_proc);
 	if ((td->td_flags & TDF_THRWAKEUP) == 0)
 		error = msleep((void *)td, &td->td_proc->p_mtx, PCATCH, "lthr",
@@ -430,6 +436,11 @@ thr_wake(struct thread *td, struct thr_wake_args *uap)
 	struct proc *p;
 	struct thread *ttd;
 
+	if (uap->id == td->td_tid) {
+		td->td_pflags |= TDP_WAKEUP;
+		return (0);
+	} 
+
 	p = td->td_proc;
 	PROC_LOCK(p);
 	ttd = thread_find(p, uap->id);
diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c
index 89faec8..328fb57 100644
--- a/sys/kern/kern_umtx.c
+++ b/sys/kern/kern_umtx.c
@@ -2170,7 +2170,7 @@ do_unlock_umutex(struct thread *td, struct umutex *m)
 
 static int
 do_cv_wait(struct thread *td, struct ucond *cv, struct umutex *m,
-	struct timespec *timeout)
+	struct timespec *timeout, u_long wflags)
 {
 	struct umtx_q *uq;
 	struct timeval tv;
@@ -2202,7 +2202,11 @@ do_cv_wait(struct thread *td, struct ucond *cv, struct umutex *m,
 	
 	umtxq_lock(&uq->uq_key);
 	if (error == 0) {
-		if (timeout == NULL) {
+		if ((wflags & UMTX_CHECK_UNPARKING) &&
+		    (td->td_pflags & TDP_WAKEUP)) {
+			td->td_pflags &= ~TDP_WAKEUP;
+			error = EINTR;
+		} else if (timeout == NULL) {
 			error = umtxq_sleep(uq, "ucond", 0);
 		} else {
 			getnanouptime(&ets);
@@ -2236,7 +2240,8 @@ do_cv_wait(struct thread *td, struct ucond *cv, struct umutex *m,
 			 * occur, and indeed a kernel based implementation
 			 * can not avoid it.
 			 */ 
-			umtxq_signal(&uq->uq_key, 1);
+			if (!umtxq_signal(&uq->uq_key, 1))
+				error = 0;
 		}
 		if (error == ERESTART)
 			error = EINTR;
@@ -2431,7 +2436,7 @@ __umtx_op_cv_wait(struct thread *td, struct _umtx_op_args *uap)
 		}
 		ts = &timeout;
 	}
-	return (do_cv_wait(td, uap->obj, uap->uaddr1, ts));
+	return (do_cv_wait(td, uap->obj, uap->uaddr1, ts, uap->val));
 }
 
 static int
@@ -2592,7 +2597,7 @@ __umtx_op_cv_wait_compat32(struct thread *td, struct _umtx_op_args *uap)
 			return (EINVAL);
 		ts = &timeout;
 	}
-	return (do_cv_wait(td, uap->obj, uap->uaddr1, ts));
+	return (do_cv_wait(td, uap->obj, uap->uaddr1, ts, uap->val));
 }
 
 static _umtx_op_func op_table_compat32[] = {
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index 454982a..99dbfc6 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -455,6 +455,7 @@ struct thread {
 #define	TDP_GEOM	0x00010000 /* Settle GEOM before finishing syscall */
 #define	TDP_SOFTDEP	0x00020000 /* Stuck processing softdep worklist */
 #define	TDP_NORUNNINGBUF 0x00040000 /* Ignore runningbufspace check */
+#define	TDP_WAKEUP	0x00080000 /* Don't sleep in umtx cond_wait */
 
 /*
  * Reasons that the current thread can not be run yet.
diff --git a/sys/sys/umtx.h b/sys/sys/umtx.h
index cfcf740..e7e534a 100644
--- a/sys/sys/umtx.h
+++ b/sys/sys/umtx.h
@@ -80,6 +80,9 @@ struct ucond {
 #define	UMTX_OP_CV_BROADCAST	10
 #define	UMTX_OP_MAX		11
 
+/* flags for UMTX_OP_CV_WAIT */
+#define UMTX_CHECK_UNPARKING	0x01
+
 #ifndef _KERNEL
 
 int _umtx_op(void *obj, int op, u_long val, void *uaddr, void *uaddr2);
-- 
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