Configurable kernel module probes support

[lttng-tools.git] / src / bin / lttng-sessiond / modprobe.c

diff --git a/src/bin/lttng-sessiond/modprobe.c b/src/bin/lttng-sessiond/modprobe.c
index 2fbc7bd8734bde95e51831b401769b0bd3d41829..3cc67f0b92c43ffe480159a42b7cc850ce19ec37 100644 (file)
--- a/src/bin/lttng-sessiond/modprobe.c
+++ b/src/bin/lttng-sessiond/modprobe.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2011 - David Goulet <dgoulet@efficios.com>
+ *               2014 - Jan Glauber <jan.glauber@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, version 2 only,
@@ -21,6 +22,7 @@
 #include <sys/wait.h>
 
 #include <common/common.h>
+#include <common/utils.h>
 
 #include "modprobe.h"
 #include "kern-modules.h"
@@ -49,7 +51,7 @@ struct kern_modules_param kern_modules_control_opt[] = {
 };
 
 /* LTTng kernel tracer probe modules list */
-const struct kern_modules_param kern_modules_probes[] = {
+struct kern_modules_param kern_modules_probes_default[] = {
        { "lttng-probe-asoc" },
        { "lttng-probe-block" },
        { "lttng-probe-btrfs" },
@@ -90,6 +92,10 @@ const struct kern_modules_param kern_modules_probes[] = {
        { "lttng-probe-writeback" },
 };
 
+/* dynamic probe modules list */
+static struct kern_modules_param *probes;
+static int nr_probes;
+
 void modprobe_remove_lttng(const struct kern_modules_param *modules,
                           int entries, int required)
 {
@@ -116,6 +122,8 @@ void modprobe_remove_lttng(const struct kern_modules_param *modules,
                        DBG("Modprobe removal successful %s",
                                        modules[i].name);
                }
+               if (probes)
+                       free(probes[i].name);
        }
 }
 
@@ -125,11 +133,11 @@ void modprobe_remove_lttng(const struct kern_modules_param *modules,
 void modprobe_remove_lttng_control(void)
 {
        modprobe_remove_lttng(kern_modules_control_opt,
-                                   ARRAY_SIZE(kern_modules_control_opt),
-                                   LTTNG_MOD_OPTIONAL);
+                             ARRAY_SIZE(kern_modules_control_opt),
+                             LTTNG_MOD_OPTIONAL);
        modprobe_remove_lttng(kern_modules_control_core,
-                                    ARRAY_SIZE(kern_modules_control_core),
-                                    LTTNG_MOD_REQUIRED);
+                             ARRAY_SIZE(kern_modules_control_core),
+                             LTTNG_MOD_REQUIRED);
 }
 
 /*
@@ -137,9 +145,14 @@ void modprobe_remove_lttng_control(void)
  */
 void modprobe_remove_lttng_data(void)
 {
-       return modprobe_remove_lttng(kern_modules_probes,
-                                    ARRAY_SIZE(kern_modules_probes),
-                                    LTTNG_MOD_OPTIONAL);
+       if (probes) {
+               modprobe_remove_lttng(probes, nr_probes, LTTNG_MOD_OPTIONAL);
+               free(probes);
+               probes = NULL;
+       } else
+               modprobe_remove_lttng(kern_modules_probes_default,
+                                     ARRAY_SIZE(kern_modules_probes_default),
+                                     LTTNG_MOD_OPTIONAL);
 }
 
 /*
@@ -151,7 +164,7 @@ void modprobe_remove_lttng_all(void)
        modprobe_remove_lttng_control();
 }
 
-static int modprobe_lttng(const struct kern_modules_param *modules,
+static int modprobe_lttng(struct kern_modules_param *modules,
                          int entries, int required)
 {
        int ret = 0, i;
@@ -195,8 +208,8 @@ int modprobe_lttng_control(void)
        if (ret != 0)
                return ret;
        ret = modprobe_lttng(kern_modules_control_opt,
-                             ARRAY_SIZE(kern_modules_control_opt),
-                             LTTNG_MOD_OPTIONAL);
+                            ARRAY_SIZE(kern_modules_control_opt),
+                            LTTNG_MOD_OPTIONAL);
        return ret;
 }
 
@@ -205,7 +218,67 @@ int modprobe_lttng_control(void)
  */
 int modprobe_lttng_data(void)
 {
-       return modprobe_lttng(kern_modules_probes,
-                             ARRAY_SIZE(kern_modules_probes),
-                             LTTNG_MOD_OPTIONAL);
+       int i, ret;
+       int entries = ARRAY_SIZE(kern_modules_probes_default);
+       char *list, *next;
+
+       /*
+        * First take command line option, if not available take environment
+        * variable.
+        */
+       if (kmod_probes_list) {
+               list = kmod_probes_list;
+       } else {
+               list = utils_get_kmod_probes_list();
+       }
+       /* The default is to load ALL probes */
+       if (!list) {
+               return modprobe_lttng(kern_modules_probes_default, entries,
+                               LTTNG_MOD_OPTIONAL);
+       }
+
+       /*
+        * A probe list is available, so use it.
+        * The number of probes is limited by the number of probes in the
+        * default list.
+        */
+       probes = zmalloc(sizeof(struct kern_modules_param *) * entries);
+       if (!probes) {
+               PERROR("malloc probe list");
+               return -ENOMEM;
+       }
+
+       for (i = 0; i < entries; i++) {
+               size_t name_len;
+
+               next = strtok(list, ",");
+               if (!next) {
+                       goto out;
+               }
+               list = NULL;
+
+               /* filter leading spaces */
+               while (*next == ' ') {
+                       next++;
+               }
+
+               /* Length 13 is "lttng-probe-" + \0 */
+               name_len = strlen(next) + 13;
+
+               probes[i].name = zmalloc(name_len);
+               if (!probes[i].name) {
+                       PERROR("malloc probe list");
+                       return -ENOMEM;
+               }
+
+               ret = snprintf(probes[i].name, name_len, "lttng-probe-%s", next);
+               if (ret < 0) {
+                       PERROR("snprintf modprobe name");
+                       goto out;
+               }
+       }
+
+out:
+       nr_probes = i;
+       return modprobe_lttng(probes, nr_probes, LTTNG_MOD_OPTIONAL);
 }