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    Subject[PATCH -tip v14 06/12] tracing: ftrace dynamic ftrace_event_call support
    Date
    Add dynamic ftrace_event_call support to ftrace. Trace engines can adds new
    ftrace_event_call to ftrace on the fly. Each operator functions of the call
    takes a 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.

    Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
    Acked-by: Frederic Weisbecker <fweisbec@gmail.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>
    ---

    include/linux/ftrace_event.h | 14 +++--
    include/linux/syscalls.h | 4 +
    include/trace/ftrace.h | 19 +++----
    include/trace/syscall.h | 8 +--
    kernel/trace/trace_events.c | 119 +++++++++++++++++++++++++++++------------
    kernel/trace/trace_export.c | 23 ++++----
    kernel/trace/trace_syscalls.c | 16 +++---
    7 files changed, 125 insertions(+), 78 deletions(-)

    diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
    index 189806b..9af68ce 100644
    --- a/include/linux/ftrace_event.h
    +++ b/include/linux/ftrace_event.h
    @@ -112,13 +112,13 @@ struct ftrace_event_call {
    struct dentry *dir;
    struct trace_event *event;
    int enabled;
    - int (*regfunc)(void *);
    - void (*unregfunc)(void *);
    + int (*regfunc)(struct ftrace_event_call *);
    + void (*unregfunc)(struct ftrace_event_call *);
    int id;
    - int (*raw_init)(void);
    - int (*show_format)(struct ftrace_event_call *call,
    - struct trace_seq *s);
    - int (*define_fields)(void);
    + int (*raw_init)(struct ftrace_event_call *);
    + int (*show_format)(struct ftrace_event_call *,
    + struct trace_seq *);
    + int (*define_fields)(struct ftrace_event_call *);
    struct list_head fields;
    int filter_active;
    struct event_filter *filter;
    @@ -142,6 +142,8 @@ extern int filter_current_check_discard(struct ftrace_event_call *call,

    extern int trace_define_field(struct ftrace_event_call *call, char *type,
    char *name, int offset, int size, int is_signed);
    +extern int trace_add_event_call(struct ftrace_event_call *call);
    +extern void trace_remove_event_call(struct ftrace_event_call *call);

    #define is_signed_type(type) (((type)(-1)) < 0)

    diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
    index 87d06c1..be59d22 100644
    --- a/include/linux/syscalls.h
    +++ b/include/linux/syscalls.h
    @@ -165,7 +165,7 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
    struct trace_event enter_syscall_print_##sname = { \
    .trace = print_syscall_enter, \
    }; \
    - static int init_enter_##sname(void) \
    + static int init_enter_##sname(struct ftrace_event_call *call) \
    { \
    int num, id; \
    num = syscall_name_to_nr("sys"#sname); \
    @@ -201,7 +201,7 @@ static void prof_sysexit_disable_##sname(struct ftrace_event_call *event_call) \
    struct trace_event exit_syscall_print_##sname = { \
    .trace = print_syscall_exit, \
    }; \
    - static int init_exit_##sname(void) \
    + static int init_exit_##sname(struct ftrace_event_call *call) \
    { \
    int num, id; \
    num = syscall_name_to_nr("sys"#sname); \
    diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
    index b250b06..6c1b5b1 100644
    --- a/include/trace/ftrace.h
    +++ b/include/trace/ftrace.h
    @@ -294,10 +294,9 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags) \
    #undef TRACE_EVENT
    #define TRACE_EVENT(call, proto, args, tstruct, func, print) \
    int \
    -ftrace_define_fields_##call(void) \
    +ftrace_define_fields_##call(struct ftrace_event_call *event_call) \
    { \
    struct ftrace_raw_##call field; \
    - struct ftrace_event_call *event_call = &event_##call; \
    int ret; \
    \
    __common_field(int, type, 1); \
    @@ -411,7 +410,7 @@ static void ftrace_profile_disable_##call(struct ftrace_event_call *event_call)\
    * event_trace_printk(_RET_IP_, "<call>: " <fmt>);
    * }
    *
    - * static int ftrace_reg_event_<call>(void)
    + * static int ftrace_reg_event_<call>(struct ftrace_event_call *unused)
    * {
    * int ret;
    *
    @@ -422,7 +421,7 @@ static void ftrace_profile_disable_##call(struct ftrace_event_call *event_call)\
    * return ret;
    * }
    *
    - * static void ftrace_unreg_event_<call>(void)
    + * static void ftrace_unreg_event_<call>(struct ftrace_event_call *unused)
    * {
    * unregister_trace_<call>(ftrace_event_<call>);
    * }
    @@ -455,7 +454,7 @@ static void ftrace_profile_disable_##call(struct ftrace_event_call *event_call)\
    * trace_current_buffer_unlock_commit(event, irq_flags, pc);
    * }
    *
    - * static int ftrace_raw_reg_event_<call>(void)
    + * static int ftrace_raw_reg_event_<call>(struct ftrace_event_call *unused)
    * {
    * int ret;
    *
    @@ -466,7 +465,7 @@ static void ftrace_profile_disable_##call(struct ftrace_event_call *event_call)\
    * return ret;
    * }
    *
    - * static void ftrace_unreg_event_<call>(void)
    + * static void ftrace_unreg_event_<call>(struct ftrace_event_call *unused)
    * {
    * unregister_trace_<call>(ftrace_raw_event_<call>);
    * }
    @@ -475,7 +474,7 @@ static void ftrace_profile_disable_##call(struct ftrace_event_call *event_call)\
    * .trace = ftrace_raw_output_<call>, <-- stage 2
    * };
    *
    - * static int ftrace_raw_init_event_<call>(void)
    + * static int ftrace_raw_init_event_<call>(struct ftrace_event_call *unused)
    * {
    * int id;
    *
    @@ -569,7 +568,7 @@ static void ftrace_raw_event_##call(proto) \
    trace_nowake_buffer_unlock_commit(event, irq_flags, pc); \
    } \
    \
    -static int ftrace_raw_reg_event_##call(void *ptr) \
    +static int ftrace_raw_reg_event_##call(struct ftrace_event_call *unused)\
    { \
    int ret; \
    \
    @@ -580,7 +579,7 @@ static int ftrace_raw_reg_event_##call(void *ptr) \
    return ret; \
    } \
    \
    -static void ftrace_raw_unreg_event_##call(void *ptr) \
    +static void ftrace_raw_unreg_event_##call(struct ftrace_event_call *unused)\
    { \
    unregister_trace_##call(ftrace_raw_event_##call); \
    } \
    @@ -589,7 +588,7 @@ static struct trace_event ftrace_event_type_##call = { \
    .trace = ftrace_raw_output_##call, \
    }; \
    \
    -static int ftrace_raw_init_event_##call(void) \
    +static int ftrace_raw_init_event_##call(struct ftrace_event_call *unused)\
    { \
    int id; \
    \
    diff --git a/include/trace/syscall.h b/include/trace/syscall.h
    index 0cb0362..848b4ae 100644
    --- a/include/trace/syscall.h
    +++ b/include/trace/syscall.h
    @@ -51,10 +51,10 @@ void set_syscall_enter_id(int num, int id);
    void set_syscall_exit_id(int num, int id);
    extern struct trace_event event_syscall_enter;
    extern struct trace_event event_syscall_exit;
    -extern int reg_event_syscall_enter(void *ptr);
    -extern void unreg_event_syscall_enter(void *ptr);
    -extern int reg_event_syscall_exit(void *ptr);
    -extern void unreg_event_syscall_exit(void *ptr);
    +extern int reg_event_syscall_enter(struct ftrace_event_call *call);
    +extern void unreg_event_syscall_enter(struct ftrace_event_call *call);
    +extern int reg_event_syscall_exit(struct ftrace_event_call *call);
    +extern void unreg_event_syscall_exit(struct ftrace_event_call *call);
    extern int
    ftrace_format_syscall(struct ftrace_event_call *call, struct trace_seq *s);
    enum print_line_t print_syscall_enter(struct trace_iterator *iter, int flags);
    diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
    index b568ade..be701d1 100644
    --- a/kernel/trace/trace_events.c
    +++ b/kernel/trace/trace_events.c
    @@ -62,9 +62,7 @@ err:
    }
    EXPORT_SYMBOL_GPL(trace_define_field);

    -#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;

    @@ -76,8 +74,6 @@ 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)
    {
    @@ -86,14 +82,14 @@ 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;
    }
    @@ -941,7 +937,7 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
    id);

    if (call->define_fields) {
    - ret = call->define_fields();
    + ret = call->define_fields(call);
    if (ret < 0) {
    pr_warning("Could not initialize trace point"
    " events/%s\n", call->name);
    @@ -961,27 +957,43 @@ 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)
    {
    @@ -1009,6 +1021,48 @@ 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)
    {
    @@ -1066,7 +1120,7 @@ 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 "
    @@ -1101,14 +1155,7 @@ 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);
    }
    }

    @@ -1226,7 +1273,7 @@ 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 956d4bc..71c8d7f 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(void); \
    -static int ftrace_raw_init_event_##call(void); \
    +int ftrace_define_fields_##call(struct ftrace_event_call *c); \
    \
    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, \
    @@ -184,9 +184,8 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
    #undef TRACE_EVENT_FORMAT
    #define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt) \
    int \
    -ftrace_define_fields_##call(void) \
    +ftrace_define_fields_##call(struct ftrace_event_call *event_call) \
    { \
    - struct ftrace_event_call *event_call = &event_##call; \
    struct args field; \
    int ret; \
    \
    diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
    index f837ccc..3451621 100644
    --- a/kernel/trace/trace_syscalls.c
    +++ b/kernel/trace/trace_syscalls.c
    @@ -210,13 +210,13 @@ void ftrace_syscall_exit(struct pt_regs *regs, long ret)
    trace_wake_up();
    }

    -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;
    @@ -234,12 +234,12 @@ 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;
    @@ -251,13 +251,13 @@ 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;
    @@ -275,12 +275,12 @@ 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;

    --
    Masami Hiramatsu

    Software Engineer
    Hitachi Computer Products (America), Inc.
    Software Solutions Division

    e-mail: mhiramat@redhat.com
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