[src/trunk]: src/sys/kern put back the cc == 0 check, because we can re-enter...

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/af66ee113dcb
branches:  trunk
changeset: 769807:af66ee113dcb
user:      christos <christos%NetBSD.org@localhost>
date:      Sat Sep 24 04:10:03 2011 +0000

description:
put back the cc == 0 check, because we can re-enter the loop with cc != 0
if we block.

diffstat:

 sys/kern/tty_pty.c |  68 ++++++++++++++++++++++++++++-------------------------
 1 files changed, 36 insertions(+), 32 deletions(-)

diffs (96 lines):

diff -r ba95c9557f64 -r af66ee113dcb sys/kern/tty_pty.c
--- a/sys/kern/tty_pty.c        Sat Sep 24 00:08:05 2011 +0000
+++ b/sys/kern/tty_pty.c        Sat Sep 24 04:10:03 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tty_pty.c,v 1.130 2011/09/23 23:57:06 christos Exp $   */
+/*     $NetBSD: tty_pty.c,v 1.131 2011/09/24 04:10:03 christos Exp $   */
 
 /*
  * Copyright (c) 1982, 1986, 1989, 1993
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tty_pty.c,v 1.130 2011/09/23 23:57:06 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tty_pty.c,v 1.131 2011/09/24 04:10:03 christos Exp $");
 
 #include "opt_ptm.h"
 
@@ -702,23 +702,25 @@
                if (tp->t_canq.c_cc)
                        goto block;
                while (uio->uio_resid > 0 && tp->t_canq.c_cc < TTYHOG) {
-                       cc = min(uio->uio_resid, BUFSIZ);
-                       cc = min(cc, TTYHOG - tp->t_canq.c_cc);
-                       cp = locbuf;
-                       mutex_spin_exit(&tty_lock);
-                       error = uiomove(cp, cc, uio);
-                       if (error != 0)
-                               return error;
-                       mutex_spin_enter(&tty_lock);
-                       /* check again for safety */
-                       if (!ISSET(tp->t_state, TS_ISOPEN)) {
-                               /*
-                                * adjust for data copied in but not
-                                * written
-                                */
-                               uio->uio_resid += cc;
-                               error = EIO;
-                               goto out;
+                       if (cc == 0) {
+                               cc = min(uio->uio_resid, BUFSIZ);
+                               cc = min(cc, TTYHOG - tp->t_canq.c_cc);
+                               cp = locbuf;
+                               mutex_spin_exit(&tty_lock);
+                               error = uiomove(cp, cc, uio);
+                               if (error != 0)
+                                       return error;
+                               mutex_spin_enter(&tty_lock);
+                               /* check again for safety */
+                               if (!ISSET(tp->t_state, TS_ISOPEN)) {
+                                       /*
+                                        * adjust for data copied in but not
+                                        * written
+                                        */
+                                       uio->uio_resid += cc;
+                                       error = EIO;
+                                       goto out;
+                               }
                        }
                        if (cc) {
                                cc = b_to_q(cp, cc, &tp->t_outq);
@@ -733,19 +735,21 @@
                goto out;
        }
        while (uio->uio_resid > 0) {
-               cc = min(uio->uio_resid, BUFSIZ);
-               cp = locbuf;
-               mutex_spin_exit(&tty_lock);
-               error = uiomove(cp, cc, uio);
-               if (error != 0)
-                       return error;
-               mutex_spin_enter(&tty_lock);
-               /* check again for safety */
-               if (!ISSET(tp->t_state, TS_ISOPEN)) {
-                       /* adjust for data copied in but not written */
-                       uio->uio_resid += cc;
-                       error = EIO;
-                       goto out;
+               if (cc == 0) {
+                       cc = min(uio->uio_resid, BUFSIZ);
+                       cp = locbuf;
+                       mutex_spin_exit(&tty_lock);
+                       error = uiomove(cp, cc, uio);
+                       if (error != 0)
+                               return error;
+                       mutex_spin_enter(&tty_lock);
+                       /* check again for safety */
+                       if (!ISSET(tp->t_state, TS_ISOPEN)) {
+                               /* adjust for data copied in but not written */
+                               uio->uio_resid += cc;
+                               error = EIO;
+                               goto out;
+                       }
                }
                while (cc > 0) {
                        int used = tp->t_rawq.c_cc + tp->t_canq.c_cc;