COM DRIVER SELECT FIX

	Patchkit 0.2 changed the way the device select interface worked,
which broke, among other things, the standard com driver.  This patch
will fix this and cure the symptom where the XFree86 server loops
continuously, eating CPU time.  The code for comselect was lifted
straight from Chris Demetriou's (cgd@agate.berkeley.edu) multiport
serial driver.

AUTHOR:		Jordan K. Hubbard (jkh@whisker.lotus.ie) & Chris Demetriou
386BSD-Patchkit: patch00079

diff --git a/usr/src/sys.386bsd/i386/i386/conf.c b/usr/src/sys.386bsd/i386/i386/conf.c
index 1815167..5a883fc 100644 (file)
--- a/usr/src/sys.386bsd/i386/i386/conf.c
+++ b/usr/src/sys.386bsd/i386/i386/conf.c
@@ -34,6 +34,13 @@
  * SUCH DAMAGE.
  *
  *     @(#)conf.c      5.8 (Berkeley) 5/12/91
  * SUCH DAMAGE.
  *
  *     @(#)conf.c      5.8 (Berkeley) 5/12/91

+ *
+ * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
+ * --------------------         -----   ----------------------
+ * CURRENT PATCH LEVEL:         1       00079
+ * --------------------         -----   ----------------------
+ *
+ * 10 Feb 93   Jordan K. Hubbard       Added select entry for com driver

  */
 static char rcsid[] = "$Header: /usr/src/sys.386bsd/i386/i386/RCS/conf.c,v 1.2 92/01/21 14:21:57 william Exp Locker: toor $";
 
  */
 static char rcsid[] = "$Header: /usr/src/sys.386bsd/i386/i386/RCS/conf.c,v 1.2 92/01/21 14:21:57 william Exp Locker: toor $";
 


@@ -152,7 +159,7 @@ struct      tty pt_tty[];
 
 #include "com.h"
 #if NCOM > 0
 
 #include "com.h"
 #if NCOM > 0

-int    comopen(),comclose(),comread(),comwrite(),comioctl();
+int    comopen(),comclose(),comread(),comwrite(),comioctl(),comselect();

 #define comreset       enxio
 extern struct tty com_tty[];
 #else
 #define comreset       enxio
 extern struct tty com_tty[];
 #else


@@ -162,6 +169,7 @@ extern      struct tty com_tty[];
 #define comwrite       enxio
 #define comioctl       enxio
 #define comreset       enxio
 #define comwrite       enxio
 #define comioctl       enxio
 #define comreset       enxio

+#define comselect      enxio

 #define        com_tty         NULL
 #endif
 
 #define        com_tty         NULL
 #endif
 


@@ -198,7 +206,7 @@ struct cdevsw       cdevsw[] =
          logselect,    enodev,         NULL },
        { comopen,      comclose,       comread,        comwrite,       /*8*/
          comioctl,     enodev,         comreset,       com_tty,
          logselect,    enodev,         NULL },
        { comopen,      comclose,       comread,        comwrite,       /*8*/
          comioctl,     enodev,         comreset,       com_tty,

-         ttselect,     enodev,         NULL },
+         comselect,    enodev,         NULL },

        { Fdopen,       fdclose,        rawread,        rawwrite,       /*9*/
          fdioctl,      enodev,         nullop,         NULL,
          seltrue,      enodev,         fdstrategy },
        { Fdopen,       fdclose,        rawread,        rawwrite,       /*9*/
          fdioctl,      enodev,         nullop,         NULL,
          seltrue,      enodev,         fdstrategy },

diff --git a/usr/src/sys.386bsd/i386/isa/com.c b/usr/src/sys.386bsd/i386/isa/com.c
index 5070b7c..348b5a1 100644 (file)
--- a/usr/src/sys.386bsd/i386/isa/com.c
+++ b/usr/src/sys.386bsd/i386/isa/com.c
@@ -34,12 +34,13 @@
  *
  * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
  * --------------------         -----   ----------------------
  *
  * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
  * --------------------         -----   ----------------------

- * CURRENT PATCH LEVEL:         3       00045
+ * CURRENT PATCH LEVEL:         4       00079

  * --------------------         -----   ----------------------
  *
  * 23 Sep 92   Rodney W. Grimes        Fix SILO overflow on 16550 UARTS
  * 30 Aug 92   Poul-Henning Kamp       Stabilize SLIP on lossy lines/UARTS
  * 09 Aug 92   Christoph Robitschko    Correct minor number on com ports
  * --------------------         -----   ----------------------
  *
  * 23 Sep 92   Rodney W. Grimes        Fix SILO overflow on 16550 UARTS
  * 30 Aug 92   Poul-Henning Kamp       Stabilize SLIP on lossy lines/UARTS
  * 09 Aug 92   Christoph Robitschko    Correct minor number on com ports

+ * 10 Feb 93   Jordan K. Hubbard       Added select code

  */
 static char rcsid[] = "$Header: /usr/bill/working/sys/i386/isa/RCS/com.c,v 1.2 92/01/21 14:34:11 william Exp $";
 
  */
 static char rcsid[] = "$Header: /usr/bill/working/sys/i386/isa/RCS/com.c,v 1.2 92/01/21 14:34:11 william Exp $";
 


@@ -723,3 +724,43 @@ comcnputc(dev, c)
        splx(s);
 }
 #endif
        splx(s);
 }
 #endif

+
+int
+comselect(dev, rw, p)
+       dev_t dev;
+       int rw;
+       struct proc *p;
+{
+       register struct tty *tp = &com_tty[UNIT(dev)];
+       int nread;
+       int s = spltty();
+        struct proc *selp;
+
+       switch (rw) {
+
+       case FREAD:
+               nread = ttnread(tp);
+               if (nread > 0 || 
+                  ((tp->t_cflag&CLOCAL) == 0 && (tp->t_state&TS_CARR_ON) == 0))
+                       goto win;
+               if (tp->t_rsel && (selp = pfind(tp->t_rsel)) && selp->p_wchan == (caddr_t)&selwait)
+                       tp->t_state |= TS_RCOLL;
+               else
+                       tp->t_rsel = p->p_pid;
+               break;
+
+       case FWRITE:
+               if (RB_LEN(&tp->t_out) <= tp->t_lowat)
+                       goto win;
+               if (tp->t_wsel && (selp = pfind(tp->t_wsel)) && selp->p_wchan == (caddr_t)&selwait)
+                       tp->t_state |= TS_WCOLL;
+               else
+                       tp->t_wsel = p->p_pid;
+               break;
+       }
+       splx(s);
+       return (0);
+  win:
+       splx(s);
+       return (1);
+}