Fix comments and enforce expected return values

[lttng-tools.git] / src / bin / lttng / commands / add_context.c

diff --git a/src/bin/lttng/commands/add_context.c b/src/bin/lttng/commands/add_context.c
index 82abc73332ad10b1117a7e95a954f39f4256108e..73aff31130e8e5e5f5489d988bff3583ae8ecc86 100644 (file)
--- a/src/bin/lttng/commands/add_context.c
+++ b/src/bin/lttng/commands/add_context.c
@@ -303,33 +303,35 @@ static void usage(FILE *ofp)
 {
        fprintf(ofp, "usage: lttng add-context -t TYPE\n");
        fprintf(ofp, "\n");
-       fprintf(ofp, "If no event name is given (-e), the context will be added to the channel\n");
        fprintf(ofp, "If no channel and no event is given (-c/-e), the context\n");
        fprintf(ofp, "will be added to all events and all channels.\n");
+       fprintf(ofp, "Otherwise the context will be added only to the channel (-c)\n");
+       fprintf(ofp, "and/or event (-e) indicated.\n");
        fprintf(ofp, "\n");
        fprintf(ofp, "Options:\n");
        fprintf(ofp, "  -h, --help               Show this help\n");
        fprintf(ofp, "      --list-options       Simple listing of options\n");
-       fprintf(ofp, "  -s, --session            Apply on session name\n");
+       fprintf(ofp, "  -s, --session NAME       Apply on session name\n");
        fprintf(ofp, "  -c, --channel NAME       Apply on channel\n");
        fprintf(ofp, "  -e, --event NAME         Apply on event\n");
-       fprintf(ofp, "  -k, --kernel             Apply for the kernel tracer\n");
+       fprintf(ofp, "  -k, --kernel             Apply to the kernel tracer\n");
 #if 0
-       fprintf(ofp, "  -u, --userspace [CMD]    Apply for the user-space tracer\n");
+       fprintf(ofp, "  -u, --userspace [CMD]    Apply to the user-space tracer\n");
        fprintf(ofp, "                           If no CMD, the domain used is UST global\n");
        fprintf(ofp, "                           or else the domain is UST EXEC_NAME\n");
        fprintf(ofp, "  -p, --pid PID            If -u, apply to specific PID (domain: UST PID)\n");
 #else
-       fprintf(ofp, "  -u, --userspace          Apply for the user-space tracer\n");
+       fprintf(ofp, "  -u, --userspace          Apply to the user-space tracer\n");
 #endif
        fprintf(ofp, "  -t, --type TYPE          Context type. You can repeat that option on\n");
-       fprintf(ofp, "                           the command line.\n");
+       fprintf(ofp, "                           the command line to specify multiple contexts at once.\n");
+       fprintf(ofp, "                           (--kernel preempts --userspace)\n");
        fprintf(ofp, "                           TYPE can be one of the strings below:\n");
        print_ctx_type(ofp);
        fprintf(ofp, "\n");
        fprintf(ofp, "Example:\n");
        fprintf(ofp, "This command will add the context information 'prio' and two perf\n"
-                       "counters: hardware branch misses and cache misses, to all events\n"
+                       "counters (hardware branch misses and cache misses), to all events\n"
                        "in the trace data output:\n");
        fprintf(ofp, "# lttng add-context -k -t prio -t perf:branch-misses -t perf:cache-misses\n");
        fprintf(ofp, "\n");
@@ -377,7 +379,7 @@ static int add_context(char *session_name)
 
        handle = lttng_create_handle(session_name, &dom);
        if (handle == NULL) {
-               ret = -1;
+               ret = CMD_ERROR;
                goto error;
        }
 
@@ -401,7 +403,7 @@ static int add_context(char *session_name)
                ret = lttng_add_context(handle, &context, opt_event_name,
                                opt_channel_name);
                if (ret < 0) {
-                       fprintf(stderr, "%s: ", type->opt->symbol);
+                       ERR("%s: ", type->opt->symbol);
                        continue;
                } else {
                        MSG("%s context %s added to %s event in %s",
@@ -411,6 +413,8 @@ static int add_context(char *session_name)
                }
        }
 
+       ret = CMD_SUCCESS;
+
 error:
        lttng_destroy_handle(handle);
 
@@ -448,6 +452,11 @@ int cmd_add_context(int argc, const char **argv)
                                ret = -1;
                                goto end;
                        }
+
+                       /*
+                        * Look up the index of opt_type in ctx_opts[] first, so we don't
+                        * have to free(type) on failure.
+                        */
                        index = find_ctx_type_idx(opt_type);
                        if (index < 0) {
                                ERR("Unknown context type %s", opt_type);