linux-kernel - [RFC PATCH v2 4/5] tracing: Use tracing error

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Message-Id: <db931dea3818fb79a710f7b83cb53b06cf565de1.1550074795.git.tom.zanussi@linux.intel.com>
Date:   Wed, 13 Feb 2019 12:17:55 -0600
From:   Tom Zanussi <zanussi@...nel.org>
To:     rostedt@...dmis.org
Cc:     tglx@...utronix.de, mhiramat@...nel.org, namhyung@...nel.org,
        bigeasy@...utronix.de, joel@...lfernandes.org,
        linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org
Subject: [RFC PATCH v2 4/5] tracing: Use tracing error_log with kprobe events (incomplete)

From: Tom Zanussi <tom.zanussi@...ux.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.zanussi@...ux.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