hw_breakpoint: Use cpu_possible_mask in {reserve,release}_bp_slot()
authorOleg Nesterov <oleg@redhat.com>
Thu, 20 Jun 2013 15:50:09 +0000 (17:50 +0200)
committerIngo Molnar <mingo@kernel.org>
Thu, 20 Jun 2013 15:57:01 +0000 (17:57 +0200)
commitc790b0ad23f427c7522ffed264706238c57c007e
treeb05dfd247ea14cbba3931b44614635b0de4760fd
parent8b4d801b2b123b6c09742f861fe44a8527b84d47
hw_breakpoint: Use cpu_possible_mask in {reserve,release}_bp_slot()

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().

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20130620155009.GA6327@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
kernel/events/hw_breakpoint.c