1 files changed, 21 insertions, 4 deletions

diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 78d8c7d6e76a..34eb9703ed33 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -42,6 +42,12 @@
 static DEFINE_MUTEX(mem_ctls_mutex);
 static LIST_HEAD(mc_devices);
 
+/*
+ * Used to lock EDAC MC to just one module, avoiding two drivers e. g.
+ *      apei/ghes and i7core_edac to be used at the same time.
+ */
+static void const *edac_mc_owner;
+
 unsigned edac_dimm_info_location(struct dimm_info *dimm, char *buf,
                                  unsigned len)
 {
@@ -659,9 +665,9 @@ fail1:
         return 1;
 }
 
-static void del_mc_from_global_list(struct mem_ctl_info *mci)
+static int del_mc_from_global_list(struct mem_ctl_info *mci)
 {
-        atomic_dec(&edac_handlers);
+        int handlers = atomic_dec_return(&edac_handlers);
         list_del_rcu(&mci->link);
 
         /* these are for safe removal of devices from global list while
@@ -669,6 +675,8 @@ static void del_mc_from_global_list(struct mem_ctl_info *mci)
          */
         synchronize_rcu();
         INIT_LIST_HEAD(&mci->link);
+
+        return handlers;
 }
 
 /**
@@ -712,6 +720,7 @@ EXPORT_SYMBOL(edac_mc_find);
 /* FIXME - should a warning be printed if no error detection? correction? */
 int edac_mc_add_mc(struct mem_ctl_info *mci)
 {
+        int ret = -EINVAL;
         edac_dbg(0, "\n");
 
 #ifdef CONFIG_EDAC_DEBUG
@@ -742,6 +751,11 @@ int edac_mc_add_mc(struct mem_ctl_info *mci)
 #endif
         mutex_lock(&mem_ctls_mutex);
 
+        if (edac_mc_owner && edac_mc_owner != mci->mod_name) {
+                ret = -EPERM;
+                goto fail0;
+        }
+
         if (add_mc_to_global_list(mci))
                 goto fail0;
 
@@ -768,6 +782,8 @@ int edac_mc_add_mc(struct mem_ctl_info *mci)
         edac_mc_printk(mci, KERN_INFO, "Giving out device to '%s' '%s':"
                 " DEV %s\n", mci->mod_name, mci->ctl_name, edac_dev_name(mci));
 
+        edac_mc_owner = mci->mod_name;
+
         mutex_unlock(&mem_ctls_mutex);
         return 0;
 
@@ -776,7 +792,7 @@ fail1:
 
 fail0:
         mutex_unlock(&mem_ctls_mutex);
-        return 1;
+        return ret;
 }
 EXPORT_SYMBOL_GPL(edac_mc_add_mc);
 
@@ -802,7 +818,8 @@ struct mem_ctl_info *edac_mc_del_mc(struct device *dev)
                 return NULL;
         }
 
-        del_mc_from_global_list(mci);
+        if (!del_mc_from_global_list(mci))
+                edac_mc_owner = NULL;
         mutex_unlock(&mem_ctls_mutex);
 
         /* flush workq processes */