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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2014-08-15 17:23:02 -0400
committerSteven Rostedt <rostedt@goodmis.org>2014-08-22 13:18:48 -0400
commit33b7f99cf003ca6c1d31c42b50e1100ad71aaec0 (patch)
tree476509236acaa87a4aa729244c703a214a5558e3 /include/linux/ftrace.h
parent7d1311b93e58ed55f3a31cc8f94c4b8fe988a2b9 (diff)
ftrace: Allow ftrace_ops to use the hashes from other ops
Currently the top level debug file system function tracer shares its ftrace_ops with the function graph tracer. This was thought to be fine because the tracers are not used together, as one can only enable function or function_graph tracer in the current_tracer file. But that assumption proved to be incorrect. The function profiler can use the function graph tracer when function tracing is enabled. Since all function graph users uses the function tracing ftrace_ops this causes a conflict and when a user enables both function profiling as well as the function tracer it will crash ftrace and disable it. The quick solution so far is to move them as separate ftrace_ops like it was earlier. The problem though is to synchronize the functions that are traced because both function and function_graph tracer are limited by the selections made in the set_ftrace_filter and set_ftrace_notrace files. To handle this, a new structure is made called ftrace_ops_hash. This structure will now hold the filter_hash and notrace_hash, and the ftrace_ops will point to this structure. That will allow two ftrace_ops to share the same hashes. Since most ftrace_ops do not share the hashes, and to keep allocation simple, the ftrace_ops structure will include both a pointer to the ftrace_ops_hash called func_hash, as well as the structure itself, called local_hash. When the ops are registered, the func_hash pointer will be initialized to point to the local_hash within the ftrace_ops structure. Some of the ftrace internal ftrace_ops will be initialized statically. This will allow for the function and function_graph tracer to have separate ops but still share the same hash tables that determine what functions they trace. Cc: stable@vger.kernel.org # 3.16 (apply after 3.17-rc4 is out) Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'include/linux/ftrace.h')
-rw-r--r--include/linux/ftrace.h14
1 files changed, 11 insertions, 3 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 6bb5e3f2a3b4..f0b0edbf55a9 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -102,6 +102,15 @@ enum {
FTRACE_OPS_FL_DELETED = 1 << 8,
};
+#ifdef CONFIG_DYNAMIC_FTRACE
+/* The hash used to know what functions callbacks trace */
+struct ftrace_ops_hash {
+ struct ftrace_hash *notrace_hash;
+ struct ftrace_hash *filter_hash;
+ struct mutex regex_lock;
+};
+#endif
+
/*
* Note, ftrace_ops can be referenced outside of RCU protection.
* (Although, for perf, the control ops prevent that). If ftrace_ops is
@@ -121,10 +130,9 @@ struct ftrace_ops {
int __percpu *disabled;
#ifdef CONFIG_DYNAMIC_FTRACE
int nr_trampolines;
- struct ftrace_hash *notrace_hash;
- struct ftrace_hash *filter_hash;
+ struct ftrace_ops_hash local_hash;
+ struct ftrace_ops_hash *func_hash;
struct ftrace_hash *tramp_hash;
- struct mutex regex_lock;
unsigned long trampoline;
#endif
};