From: Jeff Dike Date: Tue, 5 Aug 2008 20:14:06 +0000 (-0400) Subject: uml: deal with host time going backwards X-Git-Tag: v2.6.25.16~18 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bbdf9b9a28729ed1dd211368f76baef051aaecae;p=thirdparty%2Fkernel%2Fstable.git uml: deal with host time going backwards commit 06e1e4ffbd1932e288839b3140cda6b8141eb684 upstream Protection against the host's time going backwards (eg, ntp activity on the host) by keeping 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 Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/um/os-Linux/time.c b/arch/um/os-Linux/time.c index bee98f466d660..dec5678fc17f7 100644 --- a/arch/um/os-Linux/time.c +++ b/arch/um/os-Linux/time.c @@ -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 timespec *ts) 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 });