[src/trunk]: src/sys/kern Properly differentiate between infinite timeout and...

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

details:   https://anonhg.NetBSD.org/src/rev/552a9a4008a9
branches:  trunk
changeset: 785317:552a9a4008a9
user:      apb <apb%NetBSD.org@localhost>
date:      Fri Mar 08 09:32:59 2013 +0000

description:
Properly differentiate between infinite timeout and zero timeout.
Local variable timo = -1 is used for zero timeout (non blocking mode).

Fixes PR 47625 from anthony.mallet

diffstat:

 sys/kern/sys_sig.c |  20 +++++++++++++++-----
 1 files changed, 15 insertions(+), 5 deletions(-)

diffs (55 lines):

diff -r de6657a601d2 -r 552a9a4008a9 sys/kern/sys_sig.c
--- a/sys/kern/sys_sig.c        Fri Mar 08 08:48:38 2013 +0000
+++ b/sys/kern/sys_sig.c        Fri Mar 08 09:32:59 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sys_sig.c,v 1.40 2013/03/08 08:48:38 apb Exp $ */
+/*     $NetBSD: sys_sig.c,v 1.41 2013/03/08 09:32:59 apb Exp $ */
 
 /*-
  * Copyright (c) 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -66,7 +66,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_sig.c,v 1.40 2013/03/08 08:48:38 apb Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_sig.c,v 1.41 2013/03/08 09:32:59 apb Exp $");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -728,8 +728,12 @@
                        return error;
 
                timo = tstohz(&ts);
-               if (timo == 0 && ts.tv_sec == 0 && ts.tv_nsec != 0)
-                       timo++;
+               if (timo == 0) {
+                       if (ts.tv_sec == 0 && ts.tv_nsec == 0)
+                               timo = -1; /* do not block */
+                       else
+                               timo = 1; /* the shortest possible timeout */
+               }
 
                /*
                 * Remember current uptime, it would be used in
@@ -738,7 +742,7 @@
                getnanouptime(&tsstart);
        } else {
                memset(&tsstart, 0, sizeof(tsstart)); /* XXXgcc */
-               timo = 0;
+               timo = 0; /* infinite timeout */
        }
 
        error = (*fetchss)(SCARG(uap, set), &l->l_sigwaitset,
@@ -765,6 +769,12 @@
                goto out;
        }
 
+       if (timo < 0) {
+               /* If not allowed to block, return an error */
+               mutex_exit(p->p_lock);
+               return EAGAIN;
+       }
+
        /*
         * Set up the sigwait list and wait for signal to arrive.
         * We can either be woken up or time out.