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  1. 23 9月, 2008 4 次提交
    • T
      clockevents: check broadcast device not tick device · 30274569
      由 Thomas Gleixner 提交于 
      Impact: Possible hang on CPU online observed on AMD C1E machines.

The broadcast setup code looks at the mode of the tick device to
determine whether it needs to be shut down or setup. This is wrong
when the broadcast mode is set to one shot already. This can happen
when a CPU is brought online as it goes through the periodic setup
first.

The problem went unnoticed as sane systems do not call into that code
before the switch to one shot for the clock event device happens.
The AMD C1E idle routine switches over immediately and thereby shuts
down the just setup device before the first interrupt happens.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      30274569
    • T
      clockevents: prevent stale tick_next_period for onlining CPUs · 49d670fb
      由 Thomas Gleixner 提交于 
      Impact: possible hang on CPU onlining in timer one shot mode.

The tick_next_period variable is only used during boot on nohz/highres
enabled systems, but for CPU onlining it needs to be maintained when
the per cpu clock events device operates in one shot mode.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      49d670fb
    • T
      x86: prevent stale state of c1e_mask across CPU offline/online · 4faac97d
      由 Thomas Gleixner 提交于 
      Impact: hang which happens across CPU offline/online on AMD C1E systems.

When a CPU goes offline then the corresponding bit in the broadcast
mask is cleared. For AMD C1E enabled CPUs we do not reenable the
broadcast when the CPU comes online again as we do not clear the
corresponding bit in the c1e_mask, which keeps track which CPUs
have been switched to broadcast already. So on those !$@#& machines
we never switch back to broadcasting after a CPU offline/online cycle.

Clear the bit when the CPU plays dead.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      4faac97d
    • T
      clockevents: prevent cpu online to interfere with nohz · 6441402b
      由 Thomas Gleixner 提交于 
      Impact: rare hang which can be triggered on CPU online.

tick_do_timer_cpu keeps track of the CPU which updates jiffies
via do_timer. The value -1 is used to signal, that currently no
CPU is doing this. There are two cases, where the variable can 
have this state:

 boot:
    necessary for systems where the boot cpu id can be != 0

 nohz long idle sleep:
    When the CPU which did the jiffies update last goes into
    a long idle sleep it drops the update jiffies duty so
    another CPU which is not idle can pick it up and keep
    jiffies going.

Using the same value for both situations is wrong, as the CPU online
code can see the -1 state when the timer of the newly onlined CPU is
setup. The setup for a newly onlined CPU goes through periodic mode
and can pick up the do_timer duty without being aware of the nohz /
highres mode of the already running system.

Use two separate states and make them constants to avoid magic
numbers confusion. 
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      6441402b
  3. 22 9月, 2008 7 次提交
  5. 21 9月, 2008 4 次提交
  7. 20 9月, 2008 25 次提交