tracing: Kprobe tracer assigns new event ids for each event

Assign new event ids for each kprobes event. This doesn't clear
ring_buffer when unregistering each kprobe event. Thus, if you mind
'Unknown event' messages, clear the buffer manually after changing
kprobe events.

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: <20090813203534.31965.49105.stgit@localhost.localdomain>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

1 files changed, 15 insertions, 36 deletions

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 8aeb24cc295f..9c067bf47d50 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -186,6 +186,7 @@ struct trace_probe {
         };
         const char              *symbol;        /* symbol name */
         struct ftrace_event_call        call;
+        struct trace_event              event;
         unsigned int            nr_args;
         struct fetch_func       args[];
 };
@@ -795,7 +796,7 @@ static __kprobes int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
 
         size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);
 
-        event = trace_current_buffer_lock_reserve(TRACE_KPROBE, size,
+        event = trace_current_buffer_lock_reserve(call->id, size,
                                                   irq_flags, pc);
         if (!event)
                 return 0;
@@ -827,7 +828,7 @@ static __kprobes int kretprobe_trace_func(struct kretprobe_instance *ri,
 
         size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);
 
-        event = trace_current_buffer_lock_reserve(TRACE_KRETPROBE, size,
+        event = trace_current_buffer_lock_reserve(call->id, size,
                                                   irq_flags, pc);
         if (!event)
                 return 0;
@@ -853,7 +854,7 @@ print_kprobe_event(struct trace_iterator *iter, int flags)
         struct trace_seq *s = &iter->seq;
         int i;
 
-        trace_assign_type(field, iter->ent);
+        field = (struct kprobe_trace_entry *)iter->ent;
 
         if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
                 goto partial;
@@ -880,7 +881,7 @@ print_kretprobe_event(struct trace_iterator *iter, int flags)
         struct trace_seq *s = &iter->seq;
         int i;
 
-        trace_assign_type(field, iter->ent);
+        field = (struct kretprobe_trace_entry *)iter->ent;
 
         if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
                 goto partial;
@@ -906,16 +907,6 @@ partial:
         return TRACE_TYPE_PARTIAL_LINE;
 }
 
-static struct trace_event kprobe_trace_event = {
-        .type           = TRACE_KPROBE,
-        .trace          = print_kprobe_event,
-};
-
-static struct trace_event kretprobe_trace_event = {
-        .type           = TRACE_KRETPROBE,
-        .trace          = print_kretprobe_event,
-};
-
 static int probe_event_enable(struct ftrace_event_call *call)
 {
         struct trace_probe *tp = (struct trace_probe *)call->data;
@@ -1104,35 +1095,35 @@ static int register_probe_event(struct trace_probe *tp)
         /* Initialize ftrace_event_call */
         call->system = "kprobes";
         if (probe_is_return(tp)) {
-                call->event = &kretprobe_trace_event;
-                call->id = TRACE_KRETPROBE;
+                tp->event.trace = print_kretprobe_event;
                 call->raw_init = probe_event_raw_init;
                 call->show_format = kretprobe_event_show_format;
                 call->define_fields = kretprobe_event_define_fields;
         } else {
-                call->event = &kprobe_trace_event;
-                call->id = TRACE_KPROBE;
+                tp->event.trace = print_kprobe_event;
                 call->raw_init = probe_event_raw_init;
                 call->show_format = kprobe_event_show_format;
                 call->define_fields = kprobe_event_define_fields;
         }
+        call->event = &tp->event;
+        call->id = register_ftrace_event(&tp->event);
+        if (!call->id)
+                return -ENODEV;
         call->enabled = 1;
         call->regfunc = probe_event_enable;
         call->unregfunc = probe_event_disable;
         call->data = tp;
         ret = trace_add_event_call(call);
-        if (ret)
+        if (ret) {
                 pr_info("Failed to register kprobe event: %s\n", call->name);
+                unregister_ftrace_event(&tp->event);
+        }
         return ret;
 }
 
 static void unregister_probe_event(struct trace_probe *tp)
 {
-        /*
-         * Prevent to unregister event itself because the event is shared
-         * among other probes.
-         */
-        tp->call.event = NULL;
+        /* tp->event is unregistered in trace_remove_event_call() */
         trace_remove_event_call(&tp->call);
 }
 
@@ -1141,18 +1132,6 @@ static __init int init_kprobe_trace(void)
 {
         struct dentry *d_tracer;
         struct dentry *entry;
-        int ret;
-
-        ret = register_ftrace_event(&kprobe_trace_event);
-        if (!ret) {
-                pr_warning("Could not register kprobe_trace_event type.\n");
-                return 0;
-        }
-        ret = register_ftrace_event(&kretprobe_trace_event);
-        if (!ret) {
-                pr_warning("Could not register kretprobe_trace_event type.\n");
-                return 0;
-        }
 
         d_tracer = tracing_init_dentry();
         if (!d_tracer)