Protection against the host's time going backwards - keep track of the
time at the last tick and if it's greater than the current time, keep
time stopped until the host catches up.

Cc: Nix <[EMAIL PROTECTED]>
Signed-off-by: Jeff Dike <[EMAIL PROTECTED]>
---
 arch/um/os-Linux/time.c |    7 +++++++
 1 file changed, 7 insertions(+)

Index: linux-2.6-git/arch/um/os-Linux/time.c
===================================================================
--- linux-2.6-git.orig/arch/um/os-Linux/time.c  2008-05-14 10:44:02.000000000 
-0400
+++ linux-2.6-git/arch/um/os-Linux/time.c       2008-06-02 15:43:53.000000000 
-0400
@@ -106,6 +106,10 @@ static void deliver_alarm(void)
        unsigned long long this_tick = os_nsecs();
        int one_tick = UM_NSEC_PER_SEC / UM_HZ;
 
+       /* Protection against the host's time going backwards */
+       if ((last_tick != 0) && (this_tick < last_tick))
+               this_tick = last_tick;
+
        if (last_tick == 0)
                last_tick = this_tick - one_tick;
 
@@ -148,6 +152,9 @@ static int after_sleep_interval(struct t
                start_usecs = usec;
 
        start_usecs -= skew / UM_NSEC_PER_USEC;
+       if (start_usecs < 0)
+               start_usecs = 0;
+
        tv = ((struct timeval) { .tv_sec  = start_usecs / UM_USEC_PER_SEC,
                                 .tv_usec = start_usecs % UM_USEC_PER_SEC });
        interval = ((struct itimerval) { { 0, usec }, tv });

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