Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 06e1e4ff authored by Jeff Dike's avatar Jeff Dike Committed by Linus Torvalds
Browse files

uml: deal with host time going backwards 



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 <nix@esperi.org.uk>
Signed-off-by: default avatarJeff Dike <jdike@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 34397892

arch/um/os-Linux/time.c

+7 −0
Original line number Diff line number Diff line
@@ -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 });