Show error if kernel tracer version don't match

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

diff --git a/src/bin/lttng-sessiond/kernel.c b/src/bin/lttng-sessiond/kernel.c
index afa5e604fbefff9a9a2465fb5809cfe884d19f60..86a1957cf400a2f8c6cd080ff42c28a864dda427 100644 (file)
--- a/src/bin/lttng-sessiond/kernel.c
+++ b/src/bin/lttng-sessiond/kernel.c
@@ -28,6 +28,7 @@
 #include <common/kernel-ctl/kernel-ctl.h>
 
 #include "kernel.h"
+#include "kern-modules.h"
 
 /*
  * Add context on a kernel channel.
@@ -606,3 +607,66 @@ error_fp:
 error:
        return -1;
 }
+
+/*
+ * Get kernel version and validate it.
+ */
+int kernel_validate_version(int tracer_fd)
+{
+       int ret;
+       struct lttng_kernel_tracer_version version;
+
+       ret = kernctl_tracer_version(tracer_fd, &version);
+       if (ret < 0) {
+               ERR("Failed at getting the lttng-modules version");
+               goto error;
+       }
+
+       /* Validate version */
+       if (version.version != KERN_MODULES_PRE_VERSION
+               && version.version != KERN_MODULES_VERSION) {
+               goto error_version;
+       }
+
+       DBG2("Kernel tracer version validated (major version %d)", version.version);
+       return 0;
+
+error_version:
+       ERR("Kernel major version %d is not compatible (supporting <= %d)",
+                       version.version, KERN_MODULES_VERSION)
+       ret = -1;
+
+error:
+       return ret;
+}
+
+/*
+ * Kernel work-arounds called at the start of sessiond main().
+ */
+int init_kernel_workarounds(void)
+{
+       int ret;
+       FILE *fp;
+
+       /*
+        * boot_id needs to be read once before being used concurrently
+        * to deal with a Linux kernel race. A fix is proposed for
+        * upstream, but the work-around is needed for older kernels.
+        */
+       fp = fopen("/proc/sys/kernel/random/boot_id", "r");
+       if (!fp) {
+               goto end_boot_id;
+       }
+       while (!feof(fp)) {
+               char buf[37] = "";
+
+               ret = fread(buf, 1, sizeof(buf), fp);
+               if (ret < 0) {
+                       /* Ignore error, we don't really care */
+               }
+       }
+       fclose(fp);
+end_boot_id:
+
+       return 0;
+}