uprobes: Change filter_chain() to iterate ->consumers list

Now that it safe to use ->consumer_rwsem under ->mmap_sem we can
almost finish the implementation of filter_chain(). It still lacks
the actual uc->filter(...) call but othewrwise it is ready, just
it pretends that ->filter() always returns true.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 61d0fa6..4d04523 100644 (file)
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -614,14 +614,19 @@ static int prepare_uprobe(struct uprobe *uprobe, struct file *file,
 
 static bool filter_chain(struct uprobe *uprobe)
 {
-       /*
-        * TODO:
-        *      for_each_consumer(uc)
-        *              if (uc->filter(...))
-        *                      return true;
-        *      return false;
-        */
-       return uprobe->consumers != NULL;
+       struct uprobe_consumer *uc;
+       bool ret = false;
+
+       down_read(&uprobe->consumer_rwsem);
+       for (uc = uprobe->consumers; uc; uc = uc->next) {
+               /* TODO: ret = uc->filter(...) */
+               ret = true;
+               if (ret)
+                       break;
+       }
+       up_read(&uprobe->consumer_rwsem);
+
+       return ret;
 }
 
 static int