modules: use raw_cpu_write for initialization of per cpu refcount.
authorChristoph Lameter <cl@linux.com>
Mon, 7 Apr 2014 22:39:39 +0000 (15:39 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Mon, 7 Apr 2014 23:36:14 +0000 (16:36 -0700)
commit08f141d3dbddacb70aba1541bc5f950e466591e9
treeb704102a5660c8e61ca91b6f6059d72bb95330f9
parentdc322a99d31fff5d3f8acfa061ad033953efdebe
modules: use raw_cpu_write for initialization of per cpu refcount.

The initialization of a structure is not subject to synchronization.
The use of __this_cpu would trigger a false positive with the additional
preemption checks for __this_cpu ops.

So simply disable the check through the use of raw_cpu ops.

Trace:

  __this_cpu_write operation in preemptible [00000000] code: modprobe/286
  caller is __this_cpu_preempt_check+0x38/0x60
  CPU: 3 PID: 286 Comm: modprobe Tainted: GF            3.12.0-rc4+ #187
  Call Trace:
    dump_stack+0x4e/0x82
    check_preemption_disabled+0xec/0x110
    __this_cpu_preempt_check+0x38/0x60
    load_module+0xcfd/0x2650
    SyS_init_module+0xa6/0xd0
    tracesys+0xe1/0xe6

Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/module.c