ftrace: prevent freeing of all failed updates

Prevent freeing of records which cause problems and correspond to function from
core kernel text. A new flag, FTRACE_FL_CONVERTED is used to mark a record
as "converted". All other records are patched lazily to NOPs. Failed records
now also remain on frace_hash table. Each invocation of ftrace_record_ip now
checks whether the traced function has ever been recorded (including past
failures) and doesn't re-record it again.

Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 623819433ed5..20e14d0093c7 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -49,6 +49,7 @@ enum {
         FTRACE_FL_FILTER        = (1 << 2),
         FTRACE_FL_ENABLED       = (1 << 3),
         FTRACE_FL_NOTRACE       = (1 << 4),
+        FTRACE_FL_CONVERTED     = (1 << 5),
 };
 
 struct dyn_ftrace {