Author: ed
Date: Tue Jun 23 21:43:02 2009
New Revision: 194771
URL: http://svn.freebsd.org/changeset/base/194771
Log:
Improve my last commit: use a separate condvar to serialize.
The advantage of using a separate condvar is that we can just use
cv_signal(9) instead of cv_broadcast(9). It makes no sense to wake up
multiple threads. It also makes the TTY code easier to understand.
t_dcdwait sounds totally unrelated.
Modified:
head/sys/kern/tty.c
head/sys/sys/tty.h
Modified: head/sys/kern/tty.c
==============================================================================
--- head/sys/kern/tty.c Tue Jun 23 21:37:12 2009 (r194770)
+++ head/sys/kern/tty.c Tue Jun 23 21:43:02 2009 (r194771)
@@ -456,7 +456,7 @@ ttydev_write(struct cdev *dev, struct ui
} else {
/* Serialize write() calls. */
while (tp->t_flags & TF_BUSY_OUT) {
- error = tty_wait(tp, &tp->t_dcdwait);
+ error = tty_wait(tp, &tp->t_outserwait);
if (error)
goto done;
}
@@ -464,7 +464,7 @@ ttydev_write(struct cdev *dev, struct ui
tp->t_flags |= TF_BUSY_OUT;
error = ttydisc_write(tp, uio, ioflag);
tp->t_flags &= ~TF_BUSY_OUT;
- cv_broadcast(&tp->t_dcdwait);
+ cv_signal(&tp->t_outserwait);
}
done: tty_unlock(tp);
@@ -916,6 +916,7 @@ tty_alloc_mutex(struct ttydevsw *tsw, vo
cv_init(&tp->t_inwait, "ttyin");
cv_init(&tp->t_outwait, "ttyout");
+ cv_init(&tp->t_outserwait, "ttyosr");
cv_init(&tp->t_bgwait, "ttybg");
cv_init(&tp->t_dcdwait, "ttydcd");
@@ -959,6 +960,7 @@ tty_dealloc(void *arg)
cv_destroy(&tp->t_outwait);
cv_destroy(&tp->t_bgwait);
cv_destroy(&tp->t_dcdwait);
+ cv_destroy(&tp->t_outserwait);
if (tp->t_mtx == &tp->t_mtxobj)
mtx_destroy(&tp->t_mtxobj);
Modified: head/sys/sys/tty.h
==============================================================================
--- head/sys/sys/tty.h Tue Jun 23 21:37:12 2009 (r194770)
+++ head/sys/sys/tty.h Tue Jun 23 21:43:02 2009 (r194771)
@@ -97,6 +97,7 @@ struct tty {
/* Sleeping mechanisms. */
struct cv t_inwait; /* (t) Input wait queue. */
struct cv t_outwait; /* (t) Output wait queue. */
+ struct cv t_outserwait; /* (t) Serial output wait queue. */
struct cv t_bgwait; /* (t) Background wait queue. */
struct cv t_dcdwait; /* (t) Carrier Detect wait queue. */
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