[PATCH 4.13 042/109] powerpc/pseries: Dont attempt to acquire drc during memory hot add for assigned lmbs

Greg Kroah-Hartman
2017-09-24T20:41:38Z

From: John Allen <jallen@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 <jallen@linux.vnet.ibm.com>
Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@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;