X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fkernel.c;h=2936406d84f704d1a293e95dd21f248e5c5660b3;hp=a8fd844d961d06dc41a2dae3450839039fa157a6;hb=87eb4ab891dda35c54ffa95f356a4c4b198d8716;hpb=10a8a2237343699e3923d87e24dbf2d7fe225377

diff --git a/src/bin/lttng-sessiond/kernel.c b/src/bin/lttng-sessiond/kernel.c
index a8fd844d9..2936406d8 100644
--- a/src/bin/lttng-sessiond/kernel.c
+++ b/src/bin/lttng-sessiond/kernel.c
@@ -24,11 +24,11 @@
 #include <string.h>
 #include <unistd.h>
 
+#include <common/common.h>
 #include <common/kernel-ctl/kernel-ctl.h>
-#include <common/lttngerr.h>
-#include <common/lttng-share.h>
 
 #include "kernel.h"
+#include "kern-modules.h"
 
 /*
  * Add context on a kernel channel.
@@ -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);
@@ -574,15 +578,15 @@ ssize_t kernel_list_events(int tracer_fd, struct lttng_event **events)
 	 * Init memory size counter
 	 * See kernel-ctl.h for explanation of this value
 	 */
-	nbmem = KERNEL_EVENT_LIST_SIZE;
+	nbmem = KERNEL_EVENT_INIT_LIST_SIZE;
 	elist = zmalloc(sizeof(struct lttng_event) * nbmem);
 
 	while ((size = fscanf(fp, "event { name = %m[^;]; };%n\n", &event, &pos)) == 1) {
-		if (count > nbmem) {
+		if (count >= nbmem) {
 			DBG("Reallocating event list from %zu to %zu bytes", nbmem,
-					nbmem + KERNEL_EVENT_LIST_SIZE);
-			/* Adding the default size again */
-			nbmem += KERNEL_EVENT_LIST_SIZE;
+					nbmem * 2);
+			/* Double the size */
+			nbmem <<= 1;
 			elist = realloc(elist, nbmem * sizeof(struct lttng_event));
 			if (elist == NULL) {
 				perror("realloc list events");
@@ -607,3 +611,66 @@ 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.major != KERN_MODULES_PRE_MAJOR
+		&& version.major != KERN_MODULES_MAJOR) {
+		goto error_version;
+	}
+
+	DBG2("Kernel tracer version validated (major version %d)", version.major);
+	return 0;
+
+error_version:
+	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;
+}