[S390] cio: device scan oom fallback.

Since some callers rely on for_each_subchannel_staged to not fail,
fall back to brute force scanning using get_subchannel_by_schid in
case of a oom situation.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 27 insertions, 4 deletions

diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index a5fc56371ba8..1f2e424596af 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -83,6 +83,25 @@ static int call_fn_unknown_sch(struct subchannel_id schid, void *data)
         return rc;
 }
 
+static int call_fn_all_sch(struct subchannel_id schid, void *data)
+{
+        struct cb_data *cb = data;
+        struct subchannel *sch;
+        int rc = 0;
+
+        sch = get_subchannel_by_schid(schid);
+        if (sch) {
+                if (cb->fn_known_sch)
+                        rc = cb->fn_known_sch(sch, cb->data);
+                put_device(&sch->dev);
+        } else {
+                if (cb->fn_unknown_sch)
+                        rc = cb->fn_unknown_sch(schid, cb->data);
+        }
+
+        return rc;
+}
+
 int for_each_subchannel_staged(int (*fn_known)(struct subchannel *, void *),
                                int (*fn_unknown)(struct subchannel_id,
                                void *), void *data)
@@ -90,13 +109,17 @@ int for_each_subchannel_staged(int (*fn_known)(struct subchannel *, void *),
         struct cb_data cb;
         int rc;
 
-        cb.set = idset_sch_new();
-        if (!cb.set)
-                return -ENOMEM;
-        idset_fill(cb.set);
         cb.data = data;
         cb.fn_known_sch = fn_known;
         cb.fn_unknown_sch = fn_unknown;
+
+        cb.set = idset_sch_new();
+        if (!cb.set)
+                /* fall back to brute force scanning in case of oom */
+                return for_each_subchannel(call_fn_all_sch, &cb);
+
+        idset_fill(cb.set);
+
         /* Process registered subchannels. */
         rc = bus_for_each_dev(&css_bus_type, NULL, &cb, call_fn_known_sch);
         if (rc)