powerpc: Work around tracing from dyntick-idle mode
PowerPC LPAR's __trace_hcall_exit() can invoke event tracing at a
point where RCU has been told that the CPU is in dyntick-idle mode.
Because event tracing uses RCU, this can result in failures.
A correct fix would arrange for RCU to be told about dyntick-idle
mode after tracing had completed, however, this will require some care
because it appears that __trace_hcall_exit() can also be called from
non-dyntick-idle mode.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: anton@samba.org Cc: benh@kernel.crashing.org Cc: paulus@samba.org