uprobes: Kill UPROBE_RUN_HANDLER flag

Simply remove UPROBE_RUN_HANDLER and the corresponding code.

It can only help if uprobe has a single consumer, and in fact
it is no longer needed after handler_chain() was changed to use
->register_rwsem, we simply can not race with uprobe_register().

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 4d04523636869d269bb2119d0770aec4e4d0b987..7ec2eb278634cc880148bc1511db16bbda82bca1 100644 (file)
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -83,10 +83,8 @@ static atomic_t uprobe_events = ATOMIC_INIT(0);
 
 /* Have a copy of original instruction */
 #define UPROBE_COPY_INSN       0
-/* Dont run handlers when first register/ last unregister in progress*/
-#define UPROBE_RUN_HANDLER     1
 /* Can skip singlestep */
-#define UPROBE_SKIP_SSTEP      2
+#define UPROBE_SKIP_SSTEP      1
 
 struct uprobe {
        struct rb_node          rb_node;        /* node in the rb tree */
@@ -475,9 +473,6 @@ static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)
 {
        struct uprobe_consumer *uc;
 
-       if (!test_bit(UPROBE_RUN_HANDLER, &uprobe->flags))
-               return;
-
        down_read(&uprobe->register_rwsem);
        for (uc = uprobe->consumers; uc; uc = uc->next)
                uc->handler(uc, regs);
@@ -825,13 +820,8 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register)
 
 static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc)
 {
-       int err;
-
        consumer_add(uprobe, uc);
-       err = register_for_each_vma(uprobe, true);
-       if (!err) /* TODO: pointless unless the first consumer */
-               set_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
-       return err;
+       return register_for_each_vma(uprobe, true);
 }
 
 static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
@@ -842,12 +832,9 @@ static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *u
                return;
 
        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);
-       }
+       /* TODO : cant unregister? schedule a worker thread */
+       if (!uprobe->consumers && !err)
+               delete_uprobe(uprobe);
 }
 
 /*