perf/probes: Improve error messages

Improve error messages in perf-probe so that users can figure
out problems easily.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
LKML-Reference: <20091104001221.3454.52030.stgit@harusame>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index 8124523..65bcaed 100644 (file)
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -294,10 +294,11 @@ static int write_new_event(int fd, const char *buf)
 {
        int ret;
 
-       printf("Adding new event: %s\n", buf);
        ret = write(fd, buf, strlen(buf));
        if (ret <= 0)
-               die("failed to create event.");
+               die("Failed to create event.");
+       else
+               printf("Added new event: %s\n", buf);
 
        return ret;
 }
@@ -310,7 +311,7 @@ static int synthesize_probe_event(struct probe_point *pp)
        int i, len, ret;
        pp->probes[0] = buf = (char *)calloc(MAX_CMDLEN, sizeof(char));
        if (!buf)
-               die("calloc");
+               die("Failed to allocate memory by calloc.");
        ret = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
        if (ret <= 0 || ret >= MAX_CMDLEN)
                goto error;
@@ -363,7 +364,7 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
                if (ret == -E2BIG)
                        semantic_error("probe point is too long.");
                else if (ret < 0)
-                       die("snprintf");
+                       die("Failed to synthesize a probe point.");
        }
 
 #ifndef NO_LIBDWARF
@@ -375,7 +376,7 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
        else
                fd = open_default_vmlinux();
        if (fd < 0)
-               die("vmlinux/module file open");
+               die("Could not open vmlinux/module file.");
 
        /* Searching probe points */
        for (j = 0; j < session.nr_probe; j++) {
@@ -396,8 +397,13 @@ setup_probes:
        /* Settng up probe points */
        snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
        fd = open(buf, O_WRONLY, O_APPEND);
-       if (fd < 0)
-               die("kprobe_events open");
+       if (fd < 0) {
+               if (errno == ENOENT)
+                       die("kprobe_events file does not exist - please rebuild with CONFIG_KPROBE_TRACER.");
+               else
+                       die("Could not open kprobe_events file: %s",
+                           strerror(errno));
+       }
        for (j = 0; j < session.nr_probe; j++) {
                pp = &session.probes[j];
                if (pp->found == 1) {

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index db96186..35d5a69 100644 (file)
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -688,7 +688,7 @@ int find_probepoint(int fd, struct probe_point *pp)
 
        ret = dwarf_init(fd, DW_DLC_READ, 0, 0, &__dw_debug, &__dw_error);
        if (ret != DW_DLV_OK)
-               die("Failed to call dwarf_init(). Maybe, not a dwarf file.\n");
+               die("No dwarf info found in the vmlinux - please rebuild with CONFIG_DEBUG_INFO.\n");
 
        pp->found = 0;
        while (++cu_number) {