[RFC PATCH v2 4/5] tracing: Use tracing error_log with kprobe events (incomplete)

[Tom Zanussi]

From: Tom Zanussi <tom.zanu...@linux.intel.com>

Here are a few examples of replacing kprobe_events error handling with
tracing_log_err() from the new tracing error_log mechanism.  Only a
few example errors are converted, and even these are incomplete, since
I didn't know where to get the current command and used a dummy string
for those.  Also, these are completely untested, just provided for
RFC purposes.

With this change, users will find some kprobe_events errors in
tracing/error_log instead of dmesg.

TODO: If acceptable, convert all the rest of the kprobe errors and
figure out how to get the actual cmd logged along with the error.

Signed-off-by: Tom Zanussi <tom.zanu...@linux.intel.com>
---
 kernel/trace/trace_probe.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 9962cb5da8ac..3d7b195c943b 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -13,6 +13,22 @@
 
 #include "trace_probe.h"
 
+#define ERRORS                                                         \
+       C(NONE,                 "No error"),                            \
+       C(INVALID_STRING_SPEC,  "string only accepts memory or address."), \
+       C(ARG_TOO_LONG,         "Argument is too long."),               \
+       C(INVALID_ARG_NAME,     "Invalid argument name"),
+
+#undef C
+#define C(a, b)                KPROBE_ERR_##a
+
+enum { ERRORS };
+
+#undef C
+#define C(a, b)                b
+
+static const char *err_text[] = { ERRORS };
+
 const char *reserved_field_names[] = {
        "common_type",
        "common_flags",
@@ -384,7 +400,7 @@ static int traceprobe_parse_probe_arg_body(char *arg, 
ssize_t *size,
        int ret, len;
 
        if (strlen(arg) > MAX_ARGSTR_LEN) {
-               pr_info("Argument is too long.: %s\n",  arg);
+               tracing_log_err("kprobe_events", "replace this with command", 
err_text, KPROBE_ERR_ARG_TOO_LONG, err_pos("command", arg));
                return -ENOSPC;
        }
        parg->comm = kstrdup(arg, GFP_KERNEL);
@@ -443,7 +459,8 @@ static int traceprobe_parse_probe_arg_body(char *arg, 
ssize_t *size,
        if (!strcmp(parg->type->name, "string")) {
                if (code->op != FETCH_OP_DEREF && code->op != FETCH_OP_IMM &&
                    code->op != FETCH_OP_COMM) {
-                       pr_info("string only accepts memory or address.\n");
+                       tracing_log_err("kprobe_events", "replace this with 
command", err_text, KPROBE_ERR_INVALID_STRING_SPEC, 0);
+
                        ret = -EINVAL;
                        goto fail;
                }
@@ -558,8 +575,7 @@ int traceprobe_parse_probe_arg(struct trace_probe *tp, int 
i, char *arg,
                return -ENOMEM;
 
        if (!is_good_name(parg->name)) {
-               pr_info("Invalid argument[%d] name: %s\n",
-                       i, parg->name);
+               tracing_log_err("kprobe_events", "replace this with command", 
err_text, KPROBE_ERR_INVALID_ARG_NAME, err_pos("cmd", parg->name));
                return -EINVAL;
        }
 
-- 
2.14.1