tracing/kprobes: Add failure messages for debugging

Add verbose failure messages to kprobe-tracer for debugging.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20091017000728.16556.16713.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index cdacdab..b8ef707 100644 (file)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -597,15 +597,19 @@ static int create_trace_probe(int argc, char **argv)
        void *addr = NULL;
        char buf[MAX_EVENT_NAME_LEN];
 
-       if (argc < 2)
+       if (argc < 2) {
+               pr_info("Probe point is not specified.\n");
                return -EINVAL;
+       }
 
        if (argv[0][0] == 'p')
                is_return = 0;
        else if (argv[0][0] == 'r')
                is_return = 1;
-       else
+       else {
+               pr_info("Probe definition must be started with 'p' or 'r'.\n");
                return -EINVAL;
+       }
 
        if (argv[0][1] == ':') {
                event = &argv[0][2];
@@ -625,21 +629,29 @@ static int create_trace_probe(int argc, char **argv)
        }
 
        if (isdigit(argv[1][0])) {
-               if (is_return)
+               if (is_return) {
+                       pr_info("Return probe point must be a symbol.\n");
                        return -EINVAL;
+               }
                /* an address specified */
                ret = strict_strtoul(&argv[0][2], 0, (unsigned long *)&addr);
-               if (ret)
+               if (ret) {
+                       pr_info("Failed to parse address.\n");
                        return ret;
+               }
        } else {
                /* a symbol specified */
                symbol = argv[1];
                /* TODO: support .init module functions */
                ret = split_symbol_offset(symbol, &offset);
-               if (ret)
+               if (ret) {
+                       pr_info("Failed to parse symbol.\n");
                        return ret;
-               if (offset && is_return)
+               }
+               if (offset && is_return) {
+                       pr_info("Return probe must be used without offset.\n");
                        return -EINVAL;
+               }
        }
        argc -= 2; argv += 2;
 
@@ -658,8 +670,11 @@ static int create_trace_probe(int argc, char **argv)
        }
        tp = alloc_trace_probe(group, event, addr, symbol, offset, argc,
                               is_return);
-       if (IS_ERR(tp))
+       if (IS_ERR(tp)) {
+               pr_info("Failed to allocate trace_probe.(%d)\n",
+                       (int)PTR_ERR(tp));
                return PTR_ERR(tp);
+       }
 
        /* parse arguments */
        ret = 0;
@@ -672,6 +687,8 @@ static int create_trace_probe(int argc, char **argv)
                        arg = argv[i];
 
                if (conflict_field_name(argv[i], tp->args, i)) {
+                       pr_info("Argument%d name '%s' conflicts with "
+                               "another field.\n", i, argv[i]);
                        ret = -EINVAL;
                        goto error;
                }
@@ -685,8 +702,10 @@ static int create_trace_probe(int argc, char **argv)
                        goto error;
                }
                ret = parse_probe_arg(arg, &tp->args[i].fetch, is_return);
-               if (ret)
+               if (ret) {
+                       pr_info("Parse error at argument%d. (%d)\n", i, ret);
                        goto error;
+               }
        }
        tp->nr_args = i;