powerpc/powernv: Use stop_machine_cpuslocked()

set_subcores_per_core() holds get_online_cpus() while invoking stop_machine().

stop_machine() invokes get_online_cpus() as well. This is correct, but
prevents the conversion of the hotplug locking to a percpu rwsem.

Use stop_machine_cpuslocked() to avoid the nested call. Convert
*_online_cpus() to the new interfaces while at it.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20170524081548.331016542@linutronix.de

diff --git a/arch/powerpc/platforms/powernv/subcore.c b/arch/powerpc/platforms/powernv/subcore.c
index 0babef11136fc8daba7f2666fed3f3b649cc2bd8..e6230f104dd9cd545a40c2b4b92ca4a71c5cc9ba 100644 (file)
--- a/arch/powerpc/platforms/powernv/subcore.c
+++ b/arch/powerpc/platforms/powernv/subcore.c
@@ -348,7 +348,7 @@ static int set_subcores_per_core(int new_mode)
                state->master = 0;
        }
 
-       get_online_cpus();
+       cpus_read_lock();
 
        /* This cpu will update the globals before exiting stop machine */
        this_cpu_ptr(&split_state)->master = 1;
@@ -356,9 +356,10 @@ static int set_subcores_per_core(int new_mode)
        /* Ensure state is consistent before we call the other cpus */
        mb();
 
-       stop_machine(cpu_update_split_mode, &new_mode, cpu_online_mask);
+       stop_machine_cpuslocked(cpu_update_split_mode, &new_mode,
+                               cpu_online_mask);
 
-       put_online_cpus();
+       cpus_read_unlock();
 
        return 0;
 }