X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fkernel.c;h=2936406d84f704d1a293e95dd21f248e5c5660b3;hp=3b0d6e5f5ee05146aff5d2e31b61517577eed62b;hb=87eb4ab891dda35c54ffa95f356a4c4b198d8716;hpb=096102bd1f0665d96f75ad12410ea23189fbf861

diff --git a/src/bin/lttng-sessiond/kernel.c b/src/bin/lttng-sessiond/kernel.c
index 3b0d6e5f5..2936406d8 100644
--- a/src/bin/lttng-sessiond/kernel.c
+++ b/src/bin/lttng-sessiond/kernel.c
@@ -204,12 +204,16 @@ int kernel_create_event(struct lttng_event *ev,
 	}
 
 	/*
-	 * LTTNG_KERNEL_SYSCALL event creation will return 0 on success. However
-	 * this FD must not be added to the event list.
+	 * LTTNG_KERNEL_SYSCALL event creation will return 0 on success.
 	 */
 	if (ret == 0 && event->event->instrumentation == LTTNG_KERNEL_SYSCALL) {
 		DBG2("Kernel event syscall creation success");
-		goto end;
+		/*
+		 * We use fd == -1 to ensure that we never trigger a close of fd
+		 * 0.
+		 */
+		event->fd = -1;
+		goto add_list;
 	}
 
 	event->fd = ret;
@@ -219,13 +223,13 @@ int kernel_create_event(struct lttng_event *ev,
 		perror("fcntl session fd");
 	}
 
+add_list:
 	/* Add event to event list */
 	cds_list_add(&event->list, &channel->events_list.head);
 	channel->event_count++;
 
 	DBG("Event %s created (fd: %d)", ev->name, event->fd);
 
-end:
 	return 0;
 
 free_event:
@@ -484,7 +488,7 @@ int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
 	int ret;
 	struct ltt_kernel_stream *lks;
 
-	while ((ret = kernctl_create_stream(channel->fd)) > 0) {
+	while ((ret = kernctl_create_stream(channel->fd)) >= 0) {
 		lks = trace_kernel_create_stream();
 		if (lks == NULL) {
 			close(ret);
@@ -623,31 +627,50 @@ int kernel_validate_version(int tracer_fd)
 	}
 
 	/* Validate version */
-	if (version.version > KERN_MODULES_VERSION) {
+	if (version.major != KERN_MODULES_PRE_MAJOR
+		&& version.major != KERN_MODULES_MAJOR) {
 		goto error_version;
-	} else {
-		if (version.patchlevel > KERN_MODULES_PATCHLEVEL) {
-			goto error_version;
-		}
-		else {
-			if (version.sublevel > KERN_MODULES_SUBLEVEL) {
-				goto error_version;
-			}
-		}
 	}
 
-	DBG2("Kernel tracer version validated (%d.%d.%d)", version.version,
-			version.patchlevel, version.sublevel);
-
+	DBG2("Kernel tracer version validated (major version %d)", version.major);
 	return 0;
 
 error_version:
-	ERR("Kernel version is not compatible %d.%d.%d (supporting <= %d.%d.%d)",
-			version.version, version.patchlevel, version.sublevel,
-			KERN_MODULES_VERSION, KERN_MODULES_PATCHLEVEL,
-			KERN_MODULES_SUBLEVEL);
+	ERR("Kernel major version %d is not compatible (supporting <= %d)",
+			version.major, KERN_MODULES_MAJOR)
 	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;
+}