powerpc/pseries: Update CPU hotplug error recovery

Update the cpu dlpar add/remove paths to do better error recovery when
a failure occurs during the add/remove operation.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 63 insertions, 13 deletions

diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 6fb28cf229e7..a54aee982589 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -18,6 +18,8 @@
  *      2 of the License, or (at your option) any later version.
  */
 
+#define pr_fmt(fmt)     "pseries-hotplug-cpu: " fmt
+
 #include <linux/kernel.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
@@ -405,38 +407,67 @@ static bool dlpar_cpu_exists(struct device_node *parent, u32 drc_index)
 static ssize_t dlpar_cpu_add(u32 drc_index)
 {
         struct device_node *dn, *parent;
-        int rc;
+        int rc, saved_rc;
+
+        pr_debug("Attempting to add CPU, drc index: %x\n", drc_index);
 
         parent = of_find_node_by_path("/cpus");
-        if (!parent)
+        if (!parent) {
+                pr_warn("Failed to find CPU root node \"/cpus\"\n");
                 return -ENODEV;
+        }
 
         if (dlpar_cpu_exists(parent, drc_index)) {
                 of_node_put(parent);
-                printk(KERN_WARNING "CPU with drc index %x already exists\n",
-                       drc_index);
+                pr_warn("CPU with drc index %x already exists\n", 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;
         }
 
         dn = dlpar_configure_connector(cpu_to_be32(drc_index), parent);
         of_node_put(parent);
-        if (!dn)
+        if (!dn) {
+                pr_warn("Failed call to configure-connector, drc index: %x\n",
+                        drc_index);
+                dlpar_release_drc(drc_index);
                 return -EINVAL;
+        }
 
         rc = dlpar_attach_node(dn);
         if (rc) {
-                dlpar_release_drc(drc_index);
-                dlpar_free_cc_nodes(dn);
-                return rc;
+                saved_rc = rc;
+                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);
+
+                return saved_rc;
         }
 
         rc = dlpar_online_cpu(dn);
+        if (rc) {
+                saved_rc = rc;
+                pr_warn("Failed to online cpu %s, rc: %d, drc index: %x\n",
+                        dn->name, rc, drc_index);
+
+                rc = dlpar_detach_node(dn);
+                if (!rc)
+                        dlpar_release_drc(drc_index);
+
+                return saved_rc;
+        }
+
+        pr_debug("Successfully added CPU %s, drc index: %x\n", dn->name,
+                 drc_index);
         return rc;
 }
 
@@ -500,19 +531,38 @@ static ssize_t dlpar_cpu_remove(struct device_node *dn, u32 drc_index)
 {
         int rc;
 
+        pr_debug("Attemping to remove CPU %s, drc index: %x\n",
+                 dn->name, drc_index);
+
         rc = dlpar_offline_cpu(dn);
-        if (rc)
+        if (rc) {
+                pr_warn("Failed to offline CPU %s, rc: %d\n", dn->name, rc);
                 return -EINVAL;
+        }
 
         rc = dlpar_release_drc(drc_index);
-        if (rc)
+        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);
-        if (rc)
-                dlpar_acquire_drc(drc_index);
+        if (rc) {
+                int saved_rc = rc;
 
-        return rc;
+                pr_warn("Failed to detach CPU %s, rc: %d", dn->name, rc);
+
+                rc = dlpar_acquire_drc(drc_index);
+                if (!rc)
+                        dlpar_online_cpu(dn);
+
+                return saved_rc;
+        }
+
+        pr_debug("Successfully removed CPU, drc index: %x\n", drc_index);
+        return 0;
 }
 
 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE