powerpc/cpu: Modify dlpar_cpu_add and dlpar_cpu_remove to allow the
skipping of DRC index acquire or release operations during the CPU
add or remove operations.  This is intended to support subsequent
changes to provide a 'CPU readd' operation.

Signed-off-by: Michael Bringmann <m...@linux.vnet.ibm.com>
---
Changes in patch:
  -- Move new validity check added to pseries_smp_notifier
     to another patch
  -- Revise one of checks for 'acquire_drc' in dlpar_cpu_add.
  -- Revise one of checks for 'release_drc' in dlpar_cpu_remove.
---
 arch/powerpc/platforms/pseries/hotplug-cpu.c |   71 +++++++++++++++-----------
 1 file changed, 40 insertions(+), 31 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c 
b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 6ef77ca..7ede3b0 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -432,7 +432,7 @@ static bool valid_cpu_drc_index(struct device_node *parent, 
u32 drc_index)
        return found;
 }
 
-static ssize_t dlpar_cpu_add(u32 drc_index)
+static ssize_t dlpar_cpu_add(u32 drc_index, bool acquire_drc)
 {
        struct device_node *dn, *parent;
        int rc, saved_rc;
@@ -457,19 +457,22 @@ static ssize_t dlpar_cpu_add(u32 drc_index)
                return -EINVAL;
        }
 
-       rc = dlpar_acquire_drc(drc_index);
-       if (rc) {
-               pr_warn("Failed to acquire DRC, rc: %d, drc index: %x\n",
-                       rc, drc_index);
-               of_node_put(parent);
-               return -EINVAL;
+       if (acquire_drc) {
+               rc = dlpar_acquire_drc(drc_index);
+               if (rc) {
+                       pr_warn("Failed to acquire DRC, rc: %d, drc index: 
%x\n",
+                               rc, drc_index);
+                       of_node_put(parent);
+                       return -EINVAL;
+               }
        }
 
        dn = dlpar_configure_connector(cpu_to_be32(drc_index), parent);
        if (!dn) {
                pr_warn("Failed call to configure-connector, drc index: %x\n",
                        drc_index);
-               dlpar_release_drc(drc_index);
+               if (acquire_drc)
+                       dlpar_release_drc(drc_index);
                of_node_put(parent);
                return -EINVAL;
        }
@@ -484,9 +487,11 @@ static ssize_t dlpar_cpu_add(u32 drc_index)
                pr_warn("Failed to attach node %s, rc: %d, drc index: %x\n",
                        dn->name, rc, drc_index);
 
-               rc = dlpar_release_drc(drc_index);
-               if (!rc)
-                       dlpar_free_cc_nodes(dn);
+               if (acquire_drc) {
+                       rc = dlpar_release_drc(drc_index);
+                       if (!rc)
+                               dlpar_free_cc_nodes(dn);
+               }
 
                return saved_rc;
        }
@@ -498,7 +503,7 @@ static ssize_t dlpar_cpu_add(u32 drc_index)
                        dn->name, rc, drc_index);
 
                rc = dlpar_detach_node(dn);
-               if (!rc)
+               if (!rc && acquire_drc)
                        dlpar_release_drc(drc_index);
 
                return saved_rc;
@@ -566,7 +571,8 @@ static int dlpar_offline_cpu(struct device_node *dn)
 
 }
 
-static ssize_t dlpar_cpu_remove(struct device_node *dn, u32 drc_index)
+static ssize_t dlpar_cpu_remove(struct device_node *dn, u32 drc_index,
+                               bool release_drc)
 {
        int rc;
 
@@ -579,12 +585,14 @@ static ssize_t dlpar_cpu_remove(struct device_node *dn, 
u32 drc_index)
                return -EINVAL;
        }
 
-       rc = dlpar_release_drc(drc_index);
-       if (rc) {
-               pr_warn("Failed to release drc (%x) for CPU %s, rc: %d\n",
-                       drc_index, dn->name, rc);
-               dlpar_online_cpu(dn);
-               return rc;
+       if (release_drc) {
+               rc = dlpar_release_drc(drc_index);
+               if (rc) {
+                       pr_warn("Failed to release drc (%x) for CPU %s, rc: 
%d\n",
+                               drc_index, dn->name, rc);
+                       dlpar_online_cpu(dn);
+                       return rc;
+               }
        }
 
        rc = dlpar_detach_node(dn);
@@ -593,8 +601,9 @@ static ssize_t dlpar_cpu_remove(struct device_node *dn, u32 
drc_index)
 
                pr_warn("Failed to detach CPU %s, rc: %d", dn->name, rc);
 
-               rc = dlpar_acquire_drc(drc_index);
-               if (!rc)
+               if (release_drc)
+                       rc = dlpar_acquire_drc(drc_index);
+               if (!release_drc || !rc)
                        dlpar_online_cpu(dn);
 
                return saved_rc;
@@ -622,7 +631,7 @@ static struct device_node *cpu_drc_index_to_dn(u32 
drc_index)
        return dn;
 }
 
-static int dlpar_cpu_remove_by_index(u32 drc_index)
+static int dlpar_cpu_remove_by_index(u32 drc_index, bool release_drc)
 {
        struct device_node *dn;
        int rc;
@@ -634,7 +643,7 @@ static int dlpar_cpu_remove_by_index(u32 drc_index)
                return -ENODEV;
        }
 
-       rc = dlpar_cpu_remove(dn, drc_index);
+       rc = dlpar_cpu_remove(dn, drc_index, release_drc);
        of_node_put(dn);
        return rc;
 }
@@ -699,7 +708,7 @@ static int dlpar_cpu_remove_by_count(u32 cpus_to_remove)
        }
 
        for (i = 0; i < cpus_to_remove; i++) {
-               rc = dlpar_cpu_remove_by_index(cpu_drcs[i]);
+               rc = dlpar_cpu_remove_by_index(cpu_drcs[i], true);
                if (rc)
                        break;
 
@@ -710,7 +719,7 @@ static int dlpar_cpu_remove_by_count(u32 cpus_to_remove)
                pr_warn("CPU hot-remove failed, adding back removed CPUs\n");
 
                for (i = 0; i < cpus_removed; i++)
-                       dlpar_cpu_add(cpu_drcs[i]);
+                       dlpar_cpu_add(cpu_drcs[i], true);
 
                rc = -EINVAL;
        } else {
@@ -780,7 +789,7 @@ static int dlpar_cpu_add_by_count(u32 cpus_to_add)
        }
 
        for (i = 0; i < cpus_to_add; i++) {
-               rc = dlpar_cpu_add(cpu_drcs[i]);
+               rc = dlpar_cpu_add(cpu_drcs[i], true);
                if (rc)
                        break;
 
@@ -791,7 +800,7 @@ static int dlpar_cpu_add_by_count(u32 cpus_to_add)
                pr_warn("CPU hot-add failed, removing any added CPUs\n");
 
                for (i = 0; i < cpus_added; i++)
-                       dlpar_cpu_remove_by_index(cpu_drcs[i]);
+                       dlpar_cpu_remove_by_index(cpu_drcs[i], true);
 
                rc = -EINVAL;
        } else {
@@ -817,7 +826,7 @@ int dlpar_cpu(struct pseries_hp_errorlog *hp_elog)
                if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
                        rc = dlpar_cpu_remove_by_count(count);
                else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
-                       rc = dlpar_cpu_remove_by_index(drc_index);
+                       rc = dlpar_cpu_remove_by_index(drc_index, true);
                else
                        rc = -EINVAL;
                break;
@@ -825,7 +834,7 @@ int dlpar_cpu(struct pseries_hp_errorlog *hp_elog)
                if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
                        rc = dlpar_cpu_add_by_count(count);
                else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
-                       rc = dlpar_cpu_add(drc_index);
+                       rc = dlpar_cpu_add(drc_index, true);
                else
                        rc = -EINVAL;
                break;
@@ -850,7 +859,7 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t 
count)
        if (rc)
                return -EINVAL;
 
-       rc = dlpar_cpu_add(drc_index);
+       rc = dlpar_cpu_add(drc_index, true);
 
        return rc ? rc : count;
 }
@@ -871,7 +880,7 @@ static ssize_t dlpar_cpu_release(const char *buf, size_t 
count)
                return -EINVAL;
        }
 
-       rc = dlpar_cpu_remove(dn, drc_index);
+       rc = dlpar_cpu_remove(dn, drc_index, true);
        of_node_put(dn);
 
        return rc ? rc : count;

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