tracing: Ftrace dynamic ftrace_event_call support

Add dynamic ftrace_event_call support to ftrace. Trace engines can add
new ftrace_event_call to ftrace on the fly. Each operator function of
the call takes an ftrace_event_call data structure as an argument,
because these functions may be shared among several ftrace_event_calls.

Changes from v13:
 - Define remove_subsystem_dir() always (revirt a2ca5e03), because
   trace_remove_event_call() uses it.
 - Modify syscall tracer because of ftrace_event_call change.

[fweisbec@gmail.com: Fixed conflict against latest tracing/core]

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Przemysław Pawełczyk <przemyslaw@pawelczyk.it>
Cc: Roland McGrath <roland@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
LKML-Reference: <20090813203453.31965.71901.stgit@localhost.localdomain>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

3 files changed, 103 insertions, 56 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index d33bcdeffe69..8079bb511c43 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -27,8 +27,8 @@ DEFINE_MUTEX(event_mutex);
 
 LIST_HEAD(ftrace_events);
 
-int trace_define_field(struct ftrace_event_call *call, const char *type,
-                       const char *name, int offset, int size, int is_signed,
+int trace_define_field(struct ftrace_event_call *call, char *type,
+                       char *name, int offset, int size, int is_signed,
                        int filter_type)
 {
         struct ftrace_event_field *field;
@@ -92,9 +92,7 @@ int trace_define_common_fields(struct ftrace_event_call *call)
 }
 EXPORT_SYMBOL_GPL(trace_define_common_fields);
 
-#ifdef CONFIG_MODULES
-
-static void trace_destroy_fields(struct ftrace_event_call *call)
+void trace_destroy_fields(struct ftrace_event_call *call)
 {
         struct ftrace_event_field *field, *next;
 
@@ -106,8 +104,6 @@ static void trace_destroy_fields(struct ftrace_event_call *call)
         }
 }
 
-#endif /* CONFIG_MODULES */
-
 static void ftrace_event_enable_disable(struct ftrace_event_call *call,
                                         int enable)
 {
@@ -116,14 +112,14 @@ static void ftrace_event_enable_disable(struct ftrace_event_call *call,
                 if (call->enabled) {
                         call->enabled = 0;
                         tracing_stop_cmdline_record();
-                        call->unregfunc(call->data);
+                        call->unregfunc(call);
                 }
                 break;
         case 1:
                 if (!call->enabled) {
                         call->enabled = 1;
                         tracing_start_cmdline_record();
-                        call->regfunc(call->data);
+                        call->regfunc(call);
                 }
                 break;
         }
@@ -991,27 +987,43 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
         return 0;
 }
 
-#define for_each_event(event, start, end)                       \
-        for (event = start;                                     \
-             (unsigned long)event < (unsigned long)end;         \
-             event++)
+static int __trace_add_event_call(struct ftrace_event_call *call)
+{
+        struct dentry *d_events;
+        int ret;
 
-#ifdef CONFIG_MODULES
+        if (!call->name)
+                return -EINVAL;
 
-static LIST_HEAD(ftrace_module_file_list);
+        if (call->raw_init) {
+                ret = call->raw_init(call);
+                if (ret < 0) {
+                        if (ret != -ENOSYS)
+                                pr_warning("Could not initialize trace "
+                                "events/%s\n", call->name);
+                        return ret;
+                }
+        }
 
-/*
- * Modules must own their file_operations to keep up with
- * reference counting.
- */
-struct ftrace_module_file_ops {
-        struct list_head                list;
-        struct module                   *mod;
-        struct file_operations          id;
-        struct file_operations          enable;
-        struct file_operations          format;
-        struct file_operations          filter;
-};
+        d_events = event_trace_events_dir();
+        if (!d_events)
+                return -ENOENT;
+
+        list_add(&call->list, &ftrace_events);
+        return event_create_dir(call, d_events, &ftrace_event_id_fops,
+                                &ftrace_enable_fops, &ftrace_event_filter_fops,
+                                &ftrace_event_format_fops);
+}
+
+/* Add an additional event_call dynamically */
+int trace_add_event_call(struct ftrace_event_call *call)
+{
+        int ret;
+        mutex_lock(&event_mutex);
+        ret = __trace_add_event_call(call);
+        mutex_unlock(&event_mutex);
+        return ret;
+}
 
 static void remove_subsystem_dir(const char *name)
 {
@@ -1039,6 +1051,48 @@ static void remove_subsystem_dir(const char *name)
         }
 }
 
+static void __trace_remove_event_call(struct ftrace_event_call *call)
+{
+        ftrace_event_enable_disable(call, 0);
+        if (call->event)
+                __unregister_ftrace_event(call->event);
+        debugfs_remove_recursive(call->dir);
+        list_del(&call->list);
+        trace_destroy_fields(call);
+        destroy_preds(call);
+        remove_subsystem_dir(call->system);
+}
+
+/* Remove an event_call */
+void trace_remove_event_call(struct ftrace_event_call *call)
+{
+        mutex_lock(&event_mutex);
+        __trace_remove_event_call(call);
+        mutex_unlock(&event_mutex);
+}
+
+#define for_each_event(event, start, end)                       \
+        for (event = start;                                     \
+             (unsigned long)event < (unsigned long)end;         \
+             event++)
+
+#ifdef CONFIG_MODULES
+
+static LIST_HEAD(ftrace_module_file_list);
+
+/*
+ * Modules must own their file_operations to keep up with
+ * reference counting.
+ */
+struct ftrace_module_file_ops {
+        struct list_head                list;
+        struct module                   *mod;
+        struct file_operations          id;
+        struct file_operations          enable;
+        struct file_operations          format;
+        struct file_operations          filter;
+};
+
 static struct ftrace_module_file_ops *
 trace_create_file_ops(struct module *mod)
 {
@@ -1096,7 +1150,7 @@ static void trace_module_add_events(struct module *mod)
                 if (!call->name)
                         continue;
                 if (call->raw_init) {
-                        ret = call->raw_init();
+                        ret = call->raw_init(call);
                         if (ret < 0) {
                                 if (ret != -ENOSYS)
                                         pr_warning("Could not initialize trace "
@@ -1131,14 +1185,7 @@ static void trace_module_remove_events(struct module *mod)
         list_for_each_entry_safe(call, p, &ftrace_events, list) {
                 if (call->mod == mod) {
                         found = true;
-                        ftrace_event_enable_disable(call, 0);
-                        if (call->event)
-                                __unregister_ftrace_event(call->event);
-                        debugfs_remove_recursive(call->dir);
-                        list_del(&call->list);
-                        trace_destroy_fields(call);
-                        destroy_preds(call);
-                        remove_subsystem_dir(call->system);
+                        __trace_remove_event_call(call);
                 }
         }
 
@@ -1256,7 +1303,7 @@ static __init int event_trace_init(void)
                 if (!call->name)
                         continue;
                 if (call->raw_init) {
-                        ret = call->raw_init();
+                        ret = call->raw_init(call);
                         if (ret < 0) {
                                 if (ret != -ENOSYS)
                                         pr_warning("Could not initialize trace "
diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
index 029a91f42287..9cbe7f1930ea 100644
--- a/kernel/trace/trace_export.c
+++ b/kernel/trace/trace_export.c
@@ -117,10 +117,16 @@ ftrace_format_##call(struct ftrace_event_call *unused,			\
 #define TRACE_FIELD_SPECIAL(type_item, item, len, cmd)  \
         cmd;
 
+static int ftrace_raw_init_event(struct ftrace_event_call *event_call)
+{
+        INIT_LIST_HEAD(&event_call->fields);
+        init_preds(event_call);
+        return 0;
+}
+
 #undef TRACE_EVENT_FORMAT
 #define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt)      \
 int ftrace_define_fields_##call(struct ftrace_event_call *event_call);  \
-static int ftrace_raw_init_event_##call(void);                          \
                                                                         \
 struct ftrace_event_call __used                                         \
 __attribute__((__aligned__(4)))                                         \
@@ -128,16 +134,10 @@ __attribute__((section("_ftrace_events"))) event_##call = {		\
         .name                   = #call,                                \
         .id                     = proto,                                \
         .system                 = __stringify(TRACE_SYSTEM),            \
-        .raw_init               = ftrace_raw_init_event_##call,         \
+        .raw_init               = ftrace_raw_init_event,                \
         .show_format            = ftrace_format_##call,                 \
         .define_fields          = ftrace_define_fields_##call,          \
-};                                                                      \
-static int ftrace_raw_init_event_##call(void)                           \
-{                                                                       \
-        INIT_LIST_HEAD(&event_##call.fields);                           \
-        init_preds(&event_##call);                                      \
-        return 0;                                                       \
-}                                                                       \
+};
 
 #undef TRACE_EVENT_FORMAT_NOFILTER
 #define TRACE_EVENT_FORMAT_NOFILTER(call, proto, args, fmt, tstruct,    \
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 85291c4de406..5931933587e9 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -193,8 +193,8 @@ int syscall_enter_define_fields(struct ftrace_event_call *call)
                 return ret;
 
         for (i = 0; i < meta->nb_args; i++) {
-                ret = trace_define_field(call, meta->types[i],
-                                         meta->args[i], offset,
+                ret = trace_define_field(call, (char *)meta->types[i],
+                                         (char *)meta->args[i], offset,
                                          sizeof(unsigned long), 0,
                                          FILTER_OTHER);
                 offset += sizeof(unsigned long);
@@ -277,13 +277,13 @@ void ftrace_syscall_exit(struct pt_regs *regs, long ret)
                 trace_current_buffer_unlock_commit(event, 0, 0);
 }
 
-int reg_event_syscall_enter(void *ptr)
+int reg_event_syscall_enter(struct ftrace_event_call *call)
 {
         int ret = 0;
         int num;
         char *name;
 
-        name = (char *)ptr;
+        name = (char *)call->data;
         num = syscall_name_to_nr(name);
         if (num < 0 || num >= FTRACE_SYSCALL_MAX)
                 return -ENOSYS;
@@ -301,12 +301,12 @@ int reg_event_syscall_enter(void *ptr)
         return ret;
 }
 
-void unreg_event_syscall_enter(void *ptr)
+void unreg_event_syscall_enter(struct ftrace_event_call *call)
 {
         int num;
         char *name;
 
-        name = (char *)ptr;
+        name = (char *)call->data;
         num = syscall_name_to_nr(name);
         if (num < 0 || num >= FTRACE_SYSCALL_MAX)
                 return;
@@ -318,13 +318,13 @@ void unreg_event_syscall_enter(void *ptr)
         mutex_unlock(&syscall_trace_lock);
 }
 
-int reg_event_syscall_exit(void *ptr)
+int reg_event_syscall_exit(struct ftrace_event_call *call)
 {
         int ret = 0;
         int num;
         char *name;
 
-        name = (char *)ptr;
+        name = (char *)call->data;
         num = syscall_name_to_nr(name);
         if (num < 0 || num >= FTRACE_SYSCALL_MAX)
                 return -ENOSYS;
@@ -342,12 +342,12 @@ int reg_event_syscall_exit(void *ptr)
         return ret;
 }
 
-void unreg_event_syscall_exit(void *ptr)
+void unreg_event_syscall_exit(struct ftrace_event_call *call)
 {
         int num;
         char *name;
 
-        name = (char *)ptr;
+        name = (char *)call->data;
         num = syscall_name_to_nr(name);
         if (num < 0 || num >= FTRACE_SYSCALL_MAX)
                 return;