uprobes: _unregister() should always do register_for_each_vma(false)

uprobe_unregister() removes the breakpoints only if the last consumer
goes away. To support the filtering it should do this every time, we
want to remove the breakpoints which nobody else want to keep.

Note: given that filter_chain() is not actually implemented, this patch
itself doesn't change the behaviour yet, register_for_each_vma(false)
is a heavy "nop" unless there are no more consumers.

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 c38bf37d0aca9f8d623b4ee1a047d4793aef1ada..9401990846398616cc67bae2cfd10723af22d531 100644 (file)
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -825,12 +825,20 @@ static int __uprobe_register(struct uprobe *uprobe)
        return register_for_each_vma(uprobe, true);
 }
 
-static void __uprobe_unregister(struct uprobe *uprobe)
+static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
 {
-       if (!register_for_each_vma(uprobe, false))
-               delete_uprobe(uprobe);
+       int err;
+
+       if (!consumer_del(uprobe, uc))  /* WARN? */
+               return;
 
-       /* TODO : cant unregister? schedule a worker thread */
+       err = register_for_each_vma(uprobe, false);
+       if (!uprobe->consumers) {
+               clear_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
+               /* TODO : cant unregister? schedule a worker thread */
+               if (!err)
+                       delete_uprobe(uprobe);
+       }
 }
 
 /*
@@ -868,8 +876,7 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *
        } else if (!consumer_add(uprobe, uc)) {
                ret = __uprobe_register(uprobe);
                if (ret) {
-                       uprobe->consumers = NULL;
-                       __uprobe_unregister(uprobe);
+                       __uprobe_unregister(uprobe, uc);
                } else {
                        set_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
                }
@@ -897,14 +904,7 @@ void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consume
                return;
 
        mutex_lock(uprobes_hash(inode));
-
-       if (consumer_del(uprobe, uc)) {
-               if (!uprobe->consumers) {
-                       __uprobe_unregister(uprobe);
-                       clear_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
-               }
-       }
-
+       __uprobe_unregister(uprobe, uc);
        mutex_unlock(uprobes_hash(inode));
        put_uprobe(uprobe);
 }