sessiond: lttng: Add command to check kernel tracer status

[lttng-tools.git] / src / bin / lttng-sessiond / kernel.cpp

diff --git a/src/bin/lttng-sessiond/kernel.cpp b/src/bin/lttng-sessiond/kernel.cpp
index 24c3180d5eabcb05310dfbca4d3ea2207674f91e..ba82045ed86e51c18629efbbfe3a1711cd5a3dac 100644 (file)
--- a/src/bin/lttng-sessiond/kernel.cpp
+++ b/src/bin/lttng-sessiond/kernel.cpp
@@ -58,6 +58,7 @@ static uint64_t next_kernel_channel_key;
 static const char *module_proc_lttng = "/proc/lttng";
 
 static int kernel_tracer_fd = -1;
+static nonstd::optional<enum lttng_kernel_tracer_status> kernel_tracer_status = nonstd::nullopt;
 static int kernel_tracer_event_notifier_group_fd = -1;
 static int kernel_tracer_event_notifier_group_notification_fd = -1;
 static struct cds_lfht *kernel_token_to_event_notifier_rule_ht;
@@ -1949,6 +1950,48 @@ error:
        return ret;
 }
 
+/*
+ * Get current kernel tracer status
+ */
+enum lttng_kernel_tracer_status get_kernel_tracer_status()
+{
+       if (!kernel_tracer_status) {
+               return LTTNG_KERNEL_TRACER_STATUS_ERR_UNKNOWN;
+       }
+
+       return *kernel_tracer_status;
+}
+
+/*
+ * Sets the kernel tracer status based on the positive errno code
+ */
+void set_kernel_tracer_status_from_modules_ret(int code)
+{
+       switch (code) {
+       case ENOENT:
+       {
+               kernel_tracer_status = nonstd::optional<enum lttng_kernel_tracer_status>(
+                       LTTNG_KERNEL_TRACER_STATUS_ERR_MODULES_MISSING);
+               break;
+       }
+       case ENOKEY:
+       case EKEYEXPIRED:
+       case EKEYREVOKED:
+       case EKEYREJECTED:
+       {
+               kernel_tracer_status = nonstd::optional<enum lttng_kernel_tracer_status>(
+                       LTTNG_KERNEL_TRACER_STATUS_ERR_MODULES_SIGNATURE);
+               break;
+       }
+       default:
+       {
+               kernel_tracer_status = nonstd::optional<enum lttng_kernel_tracer_status>(
+                       LTTNG_KERNEL_TRACER_STATUS_ERR_MODULES_UNKNOWN);
+               break;
+       }
+       }
+}
+
 /*
  * Setup necessary data for kernel tracer action.
  */
@@ -1960,6 +2003,7 @@ int init_kernel_tracer()
        /* Modprobe lttng kernel modules */
        ret = modprobe_lttng_control();
        if (ret < 0) {
+               set_kernel_tracer_status_from_modules_ret(-ret);
                goto error;
        }
 
@@ -1967,17 +2011,22 @@ int init_kernel_tracer()
        kernel_tracer_fd = open(module_proc_lttng, O_RDWR);
        if (kernel_tracer_fd < 0) {
                DBG("Failed to open %s", module_proc_lttng);
+               kernel_tracer_status = nonstd::optional<enum lttng_kernel_tracer_status>(
+                       LTTNG_KERNEL_TRACER_STATUS_ERR_OPEN_PROC_LTTNG);
                goto error_open;
        }
 
        /* Validate kernel version */
        ret = kernel_validate_version(&the_kernel_tracer_version, &the_kernel_tracer_abi_version);
        if (ret < 0) {
+               kernel_tracer_status = nonstd::optional<enum lttng_kernel_tracer_status>(
+                       LTTNG_KERNEL_TRACER_STATUS_ERR_VERSION_MISMATCH);
                goto error_version;
        }
 
        ret = modprobe_lttng_data();
        if (ret < 0) {
+               set_kernel_tracer_status_from_modules_ret(-ret);
                goto error_modules;
        }
 
@@ -1994,6 +2043,8 @@ int init_kernel_tracer()
        ret = kernel_supports_event_notifiers();
        if (ret < 0) {
                ERR("Failed to check for kernel tracer event notifier support");
+               kernel_tracer_status = nonstd::optional<enum lttng_kernel_tracer_status>(
+                       LTTNG_KERNEL_TRACER_STATUS_ERR_NOTIFIER);
                goto error_modules;
        }
        ret = kernel_create_event_notifier_group(&kernel_tracer_event_notifier_group_fd);
@@ -2008,6 +2059,8 @@ int init_kernel_tracer()
                                &kernel_tracer_event_notifier_group_notification_fd);
 
                if (error_code_ret != LTTNG_OK) {
+                       kernel_tracer_status = nonstd::optional<enum lttng_kernel_tracer_status>(
+                               LTTNG_KERNEL_TRACER_STATUS_ERR_NOTIFIER);
                        goto error_modules;
                }
 
@@ -2016,12 +2069,16 @@ int init_kernel_tracer()
                if (error_accounting_status != EVENT_NOTIFIER_ERROR_ACCOUNTING_STATUS_OK) {
                        ERR("Failed to initialize event notifier error accounting for kernel tracer");
                        error_code_ret = LTTNG_ERR_EVENT_NOTIFIER_ERROR_ACCOUNTING;
+                       kernel_tracer_status = nonstd::optional<enum lttng_kernel_tracer_status>(
+                               LTTNG_KERNEL_TRACER_STATUS_ERR_NOTIFIER);
                        goto error_modules;
                }
 
                kernel_token_to_event_notifier_rule_ht = cds_lfht_new(
                        DEFAULT_HT_SIZE, 1, 0, CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, nullptr);
                if (!kernel_token_to_event_notifier_rule_ht) {
+                       kernel_tracer_status = nonstd::optional<enum lttng_kernel_tracer_status>(
+                               LTTNG_KERNEL_TRACER_STATUS_ERR_NOTIFIER);
                        goto error_token_ht;
                }
        }
@@ -2037,6 +2094,7 @@ int init_kernel_tracer()
                    "work for this session daemon.");
        }
 
+       kernel_tracer_status = nonstd::optional<enum lttng_kernel_tracer_status>(LTTNG_KERNEL_TRACER_STATUS_INITIALIZED);
        return 0;
 
 error_version:
@@ -2081,6 +2139,8 @@ error:
        WARN("No kernel tracer available");
        kernel_tracer_fd = -1;
        if (!is_root) {
+               kernel_tracer_status = nonstd::optional<enum lttng_kernel_tracer_status>(
+                       LTTNG_KERNEL_TRACER_STATUS_ERR_NEED_ROOT);
                return LTTNG_ERR_NEED_ROOT_SESSIOND;
        } else {
                return LTTNG_ERR_KERN_NA;
@@ -2136,6 +2196,7 @@ void cleanup_kernel_tracer()
                kernel_tracer_fd = -1;
        }
 
+       kernel_tracer_status = nonstd::nullopt;
        free(syscall_table);
 }