| commit | 5b7dba4ff834259a5623e03a565748704a8fe449 | |
| author | Dave Kleikamp <shaggy@linux.vnet.ibm.com> | |
| Thu, 9 Oct 2008 18:21:30 +0000 (9 13:21 -0500) | ||
| committer | Ingo Molnar <mingo@elte.hu> | |
| Fri, 10 Oct 2008 09:17:04 +0000 (10 11:17 +0200) | ||
| tree | 8fa9be3a308d1b5f2eb22d0a02dbe887a479ee3e | treesnapshot (tar.gz zip) |
| parent | a5d8c3483a6e19aca95ef6a2c5890e33bfa5b293 | commitdiff |
sched_clock: prevent scd->clock from moving backwards
When sched_clock_cpu() couples the clocks between two cpus, it may
increment scd->clock beyond the GTOD tick window that __update_sched_clock()
uses to clamp the clock. A later call to __update_sched_clock() may move
the clock back to scd->tick_gtod + TICK_NSEC, violating the clock's
monotonic property.
This patch ensures that scd->clock will not be set backward.
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When sched_clock_cpu() couples the clocks between two cpus, it may
increment scd->clock beyond the GTOD tick window that __update_sched_clock()
uses to clamp the clock. A later call to __update_sched_clock() may move
the clock back to scd->tick_gtod + TICK_NSEC, violating the clock's
monotonic property.
This patch ensures that scd->clock will not be set backward.
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| kernel/sched_clock.c | diffblobblamehistory |