Commit c1e16aa2 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Linus Torvalds

[PATCH] Fix posix-cpu-timer breakage caused by stale p->last_ran value

Problem description at:
http://bugzilla.kernel.org/show_bug.cgi?id=8048

Commit b18ec803
    [PATCH] sched: improve migration accuracy
optimized the scheduler time calculations, but broke posix-cpu-timers.

The problem is that the p->last_ran value is not updated after a context
switch.  So a subsequent call to current_sched_time() calculates with a
stale p->last_ran value, i.e.  accounts the full time, which the task was
scheduled away.
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ae73fc09
......@@ -3566,7 +3566,7 @@ switch_tasks:
sched_info_switch(prev, next);
if (likely(prev != next)) {
next->timestamp = now;
next->timestamp = next->last_ran = now;
rq->nr_switches++;
rq->curr = next;
++*switch_count;
......
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