From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 20 Oct 2014 22:46:44 +0000 (-0400)
Subject: Expose lttng-modules ABI version ioctl
X-Git-Tag: v2.6.0-rc1~1
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=42cabb802371ac5f22232eb494c0fdbcebd4a693;p=lttng-modules.git

Expose lttng-modules ABI version ioctl

Check compatibility between lttng-modules and tools using a version
numbering specifically for the ABI, rather than relying on the major
version of lttng-modules per se. This takes into account that we
sometimes depend on lock-step updates of the toolchain, including tools
and modules.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/lttng-abi.c b/lttng-abi.c
index 8073e988..b83ed3d2 100644
--- a/lttng-abi.c
+++ b/lttng-abi.c
@@ -188,6 +188,13 @@ void lttng_abi_tracer_version(struct lttng_kernel_tracer_version *v)
 	v->patchlevel = LTTNG_MODULES_PATCHLEVEL_VERSION;
 }
 
+static
+void lttng_abi_tracer_abi_version(struct lttng_kernel_tracer_abi_version *v)
+{
+	v->major = LTTNG_MODULES_ABI_MAJOR_VERSION;
+	v->minor = LTTNG_MODULES_ABI_MINOR_VERSION;
+}
+
 static
 long lttng_abi_add_context(struct file *file,
 	struct lttng_kernel_context *context_param,
@@ -245,6 +252,8 @@ long lttng_abi_add_context(struct file *file,
  *		Returns a file descriptor listing available tracepoints
  *	LTTNG_KERNEL_WAIT_QUIESCENT
  *		Returns after all previously running probes have completed
+ *	LTTNG_KERNEL_TRACER_ABI_VERSION
+ *		Returns the LTTng kernel tracer ABI version
  *
  * The returned session will be deleted when its file descriptor is closed.
  */
@@ -278,7 +287,19 @@ long lttng_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 			(struct lttng_kernel_tracer_version __user *) arg;
 
 		lttng_abi_tracer_version(&version);
-		
+
+		if (copy_to_user(uversion, &version, sizeof(version)))
+			return -EFAULT;
+		return 0;
+	}
+	case LTTNG_KERNEL_TRACER_ABI_VERSION:
+	{
+		struct lttng_kernel_tracer_abi_version version;
+		struct lttng_kernel_tracer_abi_version *uversion =
+			(struct lttng_kernel_tracer_abi_version __user *) arg;
+
+		lttng_abi_tracer_abi_version(&version);
+
 		if (copy_to_user(uversion, &version, sizeof(version)))
 			return -EFAULT;
 		return 0;
diff --git a/lttng-abi.h b/lttng-abi.h
index 8f5c0935..b63ead8d 100644
--- a/lttng-abi.h
+++ b/lttng-abi.h
@@ -25,6 +25,13 @@
 
 #include <linux/fs.h>
 
+/*
+ * Major/minor version of ABI exposed to lttng tools. Major number
+ * should be increased when an incompatible ABI change is done.
+ */
+#define LTTNG_MODULES_ABI_MAJOR_VERSION		1
+#define LTTNG_MODULES_ABI_MINOR_VERSION		0
+
 #define LTTNG_KERNEL_SYM_NAME_LEN	256
 
 enum lttng_kernel_instrumentation {
@@ -109,6 +116,11 @@ struct lttng_kernel_tracer_version {
 	uint32_t patchlevel;
 } __attribute__((packed));
 
+struct lttng_kernel_tracer_abi_version {
+	uint32_t major;
+	uint32_t minor;
+} __attribute__((packed));
+
 enum lttng_kernel_calibrate_type {
 	LTTNG_KERNEL_CALIBRATE_KRETPROBE,
 };
@@ -163,6 +175,8 @@ struct lttng_kernel_context {
 #define LTTNG_KERNEL_CALIBRATE			\
 	_IOWR(0xF6, 0x49, struct lttng_kernel_calibrate)
 #define LTTNG_KERNEL_SYSCALL_LIST		_IO(0xF6, 0x4A)
+#define LTTNG_KERNEL_TRACER_ABI_VERSION		\
+	_IOR(0xF6, 0x4B, struct lttng_kernel_tracer_abi_version)
 
 /* Session FD ioctl */
 #define LTTNG_KERNEL_METADATA			\