Add disable kernel tracing option to sessiond

Use --no-kernel to completely disable kernel tracing.

Reported-by: Tan Dung Le Tran <tan.dung.le.tran@ericsson.com>
Signed-off-by: David Goulet <david.goulet@polymtl.ca>

diff --git a/lttng-sessiond/main.c b/lttng-sessiond/main.c
index 262f48b8ab3b0ffc717814e9ec80e3477ee2df40..7d63656e4c401b9d66037d2c9d8126974cf6f4c5 100644 (file)
--- a/lttng-sessiond/main.c
+++ b/lttng-sessiond/main.c
@@ -92,6 +92,7 @@ const char *progname;
 const char *opt_tracing_group;
 static int opt_sig_parent;
 static int opt_daemon;
+static int opt_no_kernel;
 static int is_root;                    /* Set to 1 if the daemon is running as root */
 static pid_t ppid;          /* Parent PID for --sig-parent option */
 static char *rundir;
@@ -457,10 +458,9 @@ static void cleanup(void)
 
        pthread_mutex_destroy(&kconsumer_data.pid_mutex);
 
-       DBG("Closing kernel fd");
-       close(kernel_tracer_fd);
-
-       if (is_root) {
+       if (is_root && !opt_no_kernel) {
+               DBG2("Closing kernel fd");
+               close(kernel_tracer_fd);
                DBG("Unloading kernel modules");
                modprobe_remove_kernel_modules();
        }
@@ -3162,6 +3162,11 @@ static int process_client_msg(struct command_ctx *cmd_ctx)
 
        DBG("Processing client command %d", cmd_ctx->lsm->cmd_type);
 
+       if (opt_no_kernel && cmd_ctx->lsm->domain.type == LTTNG_DOMAIN_KERNEL) {
+               ret = LTTCOMM_KERN_NA;
+               goto error;
+       }
+
        /*
         * Check for command that don't needs to allocate a returned payload. We do
         * this here so we don't have to make the call for no payload at each
@@ -3731,6 +3736,7 @@ static void usage(void)
        fprintf(stderr, "  -q, --quiet                        No output at all.\n");
        fprintf(stderr, "  -v, --verbose                      Verbose mode. Activate DBG() macro.\n");
        fprintf(stderr, "      --verbose-consumer             Verbose mode for consumer. Activate DBG() macro.\n");
+       fprintf(stderr, "      --no-kernel                    Disable kernel tracer\n");
 }
 
 /*
@@ -3761,12 +3767,13 @@ static int parse_args(int argc, char **argv)
                { "quiet", 0, 0, 'q' },
                { "verbose", 0, 0, 'v' },
                { "verbose-consumer", 0, 0, 'Z' },
+               { "no-kernel", 0, 0, 'N' },
                { NULL, 0, 0, 0 }
        };
 
        while (1) {
                int option_index = 0;
-               c = getopt_long(argc, argv, "dhqvVS" "a:c:g:s:C:E:D:F:Z:u:t",
+               c = getopt_long(argc, argv, "dhqvVSN" "a:c:g:s:C:E:D:F:Z:u:t",
                                long_options, &option_index);
                if (c == -1) {
                        break;
@@ -3818,6 +3825,9 @@ static int parse_args(int argc, char **argv)
                case 'G':
                        snprintf(ustconsumer32_data.cmd_unix_sock_path, PATH_MAX, "%s", optarg);
                        break;
+               case 'N':
+                       opt_no_kernel = 1;
+                       break;
                case 'q':
                        opt_quiet = 1;
                        break;
@@ -4329,7 +4339,9 @@ int main(int argc, char **argv)
                }
 
                /* Setup kernel tracer */
-               init_kernel_tracer();
+               if (!opt_no_kernel) {
+                       init_kernel_tracer();
+               }
 
                /* Set ulimit for open files */
                set_ulimit();