4.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: John Allen <jal...@linux.vnet.ibm.com>

commit afb5519fdb346201728040cab4e08ce53e7ff4fd upstream.

Check if an LMB is assigned before attempting to call dlpar_acquire_drc
in order to avoid any unnecessary rtas calls. This substantially
reduces the running time of memory hot add on lpars with large amounts
of memory.

[mpe: We need to explicitly set rc to 0 in the success case, otherwise
 the compiler might think we use rc without initialising it.]

Fixes: c21f515c7436 ("powerpc/pseries: Make the acquire/release of the drc for 
memory a seperate step")
Signed-off-by: John Allen <jal...@linux.vnet.ibm.com>
Reviewed-by: Nathan Fontenot <nf...@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 arch/powerpc/platforms/pseries/hotplug-memory.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -817,6 +817,9 @@ static int dlpar_memory_add_by_count(u32
                return -EINVAL;
 
        for (i = 0; i < num_lmbs && lmbs_to_add != lmbs_added; i++) {
+               if (lmbs[i].flags & DRCONF_MEM_ASSIGNED)
+                       continue;
+
                rc = dlpar_acquire_drc(lmbs[i].drc_index);
                if (rc)
                        continue;
@@ -859,6 +862,7 @@ static int dlpar_memory_add_by_count(u32
                                lmbs[i].base_addr, lmbs[i].drc_index);
                        lmbs[i].reserved = 0;
                }
+               rc = 0;
        }
 
        return rc;


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