uml: deal with host time going backwards
PATCH 6/14 uml: deal with host time going backwards
From b547462b600e9d284f9d40ed558ca2b8904af185 Mon Sep 17 00:00:00 2001
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 <[email protected]>
Signed-off-by Jeff Dike <[email protected]>
Signed-off-by Andrew Morton <[email protected]>
Signed-off-by Linus Torvalds <[email protected]>
--- arch/um/os-Linux/time.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-)
arch/um/os-Linux/time.c +7 -0
@@ -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 });
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