Re: [PATCH 2/2] hw_breakpoint: Use cpu_possible_mask in{reserve,release}_bp_slot()

[Frederic Weisbecker]

On Sat, Jun 01, 2013 at 08:21:39PM +0200, Oleg Nesterov wrote:
> fetch_bp_busy_slots() and toggle_bp_slot() use for_each_online_cpu(),
> this is obviously wrong wrt cpu_up() or cpu_down(), we can over/under
> account the per-cpu numbers.
> 
> For example:
> 
> 	# echo 0 >> /sys/devices/system/cpu/cpu1/online
> 	# perf record -e mem:0x10 -p 1 &
> 	# echo 1 >> /sys/devices/system/cpu/cpu1/online
> 	# perf record -e mem:0x10,mem:0x10,mem:0x10,mem:0x10 -C1 -a &
> 	# taskset -p 0x2 1
> 
> triggers the same WARN_ONCE("Can't find any breakpoint slot") in
> arch_install_hw_breakpoint().
> 
> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>

Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
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