ehea: fix possible DLPAR/mem deadlock

Force serialization of userspace-triggered DLPAR/mem operations

Signed-off-by: Thomas Klein <tklein@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 5 deletions

diff --git a/drivers/net/ehea/ehea_main.c b/drivers/net/ehea/ehea_main.c
index c35d1e3631d1..39774817c3eb 100644
--- a/drivers/net/ehea/ehea_main.c
+++ b/drivers/net/ehea/ehea_main.c
@@ -2889,7 +2889,6 @@ static void ehea_rereg_mrs(struct work_struct *work)
         int ret, i;
         struct ehea_adapter *adapter;
 
-        mutex_lock(&dlpar_mem_lock);
         ehea_info("LPAR memory changed - re-initializing driver");
 
         list_for_each_entry(adapter, &adapter_list, list)
@@ -2959,7 +2958,6 @@ static void ehea_rereg_mrs(struct work_struct *work)
                 }
         ehea_info("re-initializing driver complete");
 out:
-        mutex_unlock(&dlpar_mem_lock);
         return;
 }
 
@@ -3542,7 +3540,14 @@ void ehea_crash_handler(void)
 static int ehea_mem_notifier(struct notifier_block *nb,
                              unsigned long action, void *data)
 {
+        int ret = NOTIFY_BAD;
         struct memory_notify *arg = data;
+
+        if (!mutex_trylock(&dlpar_mem_lock)) {
+                ehea_info("ehea_mem_notifier must not be called parallelized");
+                goto out;
+        }
+
         switch (action) {
         case MEM_CANCEL_OFFLINE:
                 ehea_info("memory offlining canceled");
@@ -3551,14 +3556,14 @@ static int ehea_mem_notifier(struct notifier_block *nb,
                 ehea_info("memory is going online");
                 set_bit(__EHEA_STOP_XFER, &ehea_driver_flags);
                 if (ehea_add_sect_bmap(arg->start_pfn, arg->nr_pages))
-                        return NOTIFY_BAD;
+                        goto out_unlock;
                 ehea_rereg_mrs(NULL);
                 break;
         case MEM_GOING_OFFLINE:
                 ehea_info("memory is going offline");
                 set_bit(__EHEA_STOP_XFER, &ehea_driver_flags);
                 if (ehea_rem_sect_bmap(arg->start_pfn, arg->nr_pages))
-                        return NOTIFY_BAD;
+                        goto out_unlock;
                 ehea_rereg_mrs(NULL);
                 break;
         default:
@@ -3566,8 +3571,12 @@ static int ehea_mem_notifier(struct notifier_block *nb,
         }
 
         ehea_update_firmware_handles();
+        ret = NOTIFY_OK;
 
-        return NOTIFY_OK;
+out_unlock:
+        mutex_unlock(&dlpar_mem_lock);
+out:
+        return ret;
 }
 
 static struct notifier_block ehea_mem_nb = {