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author | Peter Zijlstra <peterz@infradead.org> | 2013-09-23 17:04:26 (GMT) |
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committer | Ingo Molnar <mingo@kernel.org> | 2013-09-25 12:07:55 (GMT) |
commit | a233f1120c37724938f7201fe2353b2577adaaf9 (patch) | |
tree | 9d7b0887b3398a1fc699ea557822c891bf9c450d /sound | |
parent | bdb43806589096ac4272fe1307e789846ac08d7c (diff) | |
download | linux-a233f1120c37724938f7201fe2353b2577adaaf9.tar.xz |
sched: Prepare for per-cpu preempt_count
When using per-cpu preempt_count variables we need to save/restore the
preempt_count on context switch (into per task storage; for instance
the old thread_info::preempt_count variable) because of
PREEMPT_ACTIVE.
However, this means that on fork() the preempt_count value of the last
context switch gets copied and if we had a PREEMPT_ACTIVE switch right
before cloning a child task the child task will now too have
PREEMPT_ACTIVE set and start its life with an extra PREEMPT_ACTIVE
count.
Therefore we need to make init_task_preempt_count() unconditional;
this resets whatever preempt_count we inherited from our parent
process.
Doing so for !per-cpu implementations is harmless.
For !PREEMPT_COUNT kernels we need to be careful not to start life
with an increased preempt_count.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-4k0b7oy1rcdyzochwiixuwi9@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'sound')
0 files changed, 0 insertions, 0 deletions