ftrace: Update all ftrace_ops for a ftrace_hash_ops update

When updating what an ftrace_ops traces, if it is registered (that is,
actively tracing), and that ftrace_ops uses the shared global_ops
local_hash, then we need to update all tracers that are active and
also share the global_ops' ftrace_hash_ops.

Cc: stable@vger.kernel.org # 3.16 (apply after 3.17-rc4 is out)
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 39 insertions, 4 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index c92757adba79..37f9e90d241c 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1292,9 +1292,9 @@ alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash)
 }
 
 static void
-ftrace_hash_rec_disable(struct ftrace_ops *ops, int filter_hash);
+ftrace_hash_rec_disable_modify(struct ftrace_ops *ops, int filter_hash);
 static void
-ftrace_hash_rec_enable(struct ftrace_ops *ops, int filter_hash);
+ftrace_hash_rec_enable_modify(struct ftrace_ops *ops, int filter_hash);
 
 static int
 ftrace_hash_move(struct ftrace_ops *ops, int enable,
@@ -1346,13 +1346,13 @@ update:
          * Remove the current set, update the hash and add
          * them back.
          */
-        ftrace_hash_rec_disable(ops, enable);
+        ftrace_hash_rec_disable_modify(ops, enable);
 
         old_hash = *dst;
         rcu_assign_pointer(*dst, new_hash);
         free_ftrace_hash_rcu(old_hash);
 
-        ftrace_hash_rec_enable(ops, enable);
+        ftrace_hash_rec_enable_modify(ops, enable);
 
         return 0;
 }
@@ -1686,6 +1686,41 @@ static void ftrace_hash_rec_enable(struct ftrace_ops *ops,
         __ftrace_hash_rec_update(ops, filter_hash, 1);
 }
 
+static void ftrace_hash_rec_update_modify(struct ftrace_ops *ops,
+                                          int filter_hash, int inc)
+{
+        struct ftrace_ops *op;
+
+        __ftrace_hash_rec_update(ops, filter_hash, inc);
+
+        if (ops->func_hash != &global_ops.local_hash)
+                return;
+
+        /*
+         * If the ops shares the global_ops hash, then we need to update
+         * all ops that are enabled and use this hash.
+         */
+        do_for_each_ftrace_op(op, ftrace_ops_list) {
+                /* Already done */
+                if (op == ops)
+                        continue;
+                if (op->func_hash == &global_ops.local_hash)
+                        __ftrace_hash_rec_update(op, filter_hash, inc);
+        } while_for_each_ftrace_op(op);
+}
+
+static void ftrace_hash_rec_disable_modify(struct ftrace_ops *ops,
+                                           int filter_hash)
+{
+        ftrace_hash_rec_update_modify(ops, filter_hash, 0);
+}
+
+static void ftrace_hash_rec_enable_modify(struct ftrace_ops *ops,
+                                          int filter_hash)
+{
+        ftrace_hash_rec_update_modify(ops, filter_hash, 1);
+}
+
 static void print_ip_ins(const char *fmt, unsigned char *p)
 {
         int i;