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SubjectRe: [PATCH 6/7] add syscall tracepoints
On Fri, Jun 12, 2009 at 05:25:04PM -0400, Jason Baron wrote:
> Allow the return value of raw_init() to bail us out of creating a trace event
> file.
>
> Signed-off-by: Jason Baron <jbaron@redhat.com>
>
> ---
> kernel/trace/trace_events.c | 29 +++++++++++++++++++----------
> 1 files changed, 19 insertions(+), 10 deletions(-)
>
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 9e91c4a..c0da5e2 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -907,15 +907,6 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
> if (strcmp(call->system, TRACE_SYSTEM) != 0)
> d_events = event_subsystem_dir(call->system, d_events);
>
> - if (call->raw_init) {
> - ret = call->raw_init();
> - if (ret < 0) {
> - pr_warning("Could not initialize trace point"
> - " events/%s\n", call->name);
> - return ret;
> - }
> - }
> -
> call->dir = debugfs_create_dir(call->name, d_events);
> if (!call->dir) {
> pr_warning("Could not create debugfs "
> @@ -1014,6 +1005,7 @@ static void trace_module_add_events(struct module *mod)
> struct ftrace_module_file_ops *file_ops = NULL;
> struct ftrace_event_call *call, *start, *end;
> struct dentry *d_events;
> + int ret;
>
> start = mod->trace_events;
> end = mod->trace_events + mod->num_trace_events;
> @@ -1029,7 +1021,15 @@ static void trace_module_add_events(struct module *mod)
> /* The linker may leave blanks */
> if (!call->name)
> continue;
> -
> + if (call->raw_init) {
> + ret = call->raw_init();
> + if (ret < 0) {
> + if (ret != -ENOSYS)



I see you've set it up in case syscall_to_nr doesn't find the
matching metadata.

How is it possible? The traced syscalls, ie those which are defined through
DEFINE_SYSCALLx(), should be all in the arch syscall table. Or may be I'm
missing something?

In this case we should warn because it would reveal a bug.



> + pr_warning("Could not initialize trace"
> + "point events/%s\n", call->name);
> + continue;
> + }
> + }
> /*
> * This module has events, create file ops for this module
> * if not already done.
> @@ -1167,6 +1167,15 @@ static __init int event_trace_init(void)
> /* The linker may leave blanks */
> if (!call->name)
> continue;
> + if (call->raw_init) {
> + ret = call->raw_init();
> + if (ret < 0) {
> + if (ret != -ENOSYS)
> + pr_warning("Could not initialize trace"
> + "point events/%s\n", call->name);
> + continue;
> + }
> + }
> list_add(&call->list, &ftrace_events);
> event_create_dir(call, d_events, &ftrace_event_id_fops,
> &ftrace_enable_fops, &ftrace_event_filter_fops,
> --
> 1.6.0.6
>



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