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author | Thomas Gleixner <tglx@linutronix.de> | 2007-09-16 09:36:43 -0400 |
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committer | Thomas Gleixner <tglx@chaos.(none)> | 2007-09-16 09:36:43 -0400 |
commit | 5e41d0d60a534d2a5dc9772600a58f44c8d12506 (patch) | |
tree | d020ec1e72c338f3bf9dc4558ac3c82527a02384 /include | |
parent | 31d9b3938c0459e5e9755ce0a98ac1e24eeff972 (diff) |
clockevents: prevent stale tick update on offline cpu
Taking a cpu offline removes the cpu from the online mask before the
CPU_DEAD notification is done. The clock events layer does the cleanup
of the dead CPU from the CPU_DEAD notifier chain. tick_do_timer_cpu is
used to avoid xtime lock contention by assigning the task of jiffies
xtime updates to one CPU. If a CPU is taken offline, then this
assignment becomes stale. This went unnoticed because most of the time
the offline CPU went dead before the online CPU reached __cpu_die(),
where the CPU_DEAD state is checked. In the case that the offline CPU did
not reach the DEAD state before we reach __cpu_die(), the code in there
goes to sleep for 100ms. Due to the stale time update assignment, the
system is stuck forever.
Take the assignment away when a cpu is not longer in the cpu_online_mask.
We do this in the last call to tick_nohz_stop_sched_tick() when the offline
CPU is on the way to the final play_dead() idle entry.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include')
0 files changed, 0 insertions, 0 deletions