From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 26 May 2011 02:54:11 +0000 (-0400)
Subject: Add comm context
X-Git-Tag: v2.0-pre1~79
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=25b2f99ab44a986f4850ece6eaadb2ead024c924;p=lttng-modules.git

Add comm context

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

diff --git a/Makefile b/Makefile
index 01b0e7ee..8f364dbf 100644
--- a/Makefile
+++ b/Makefile
@@ -12,7 +12,7 @@ obj-m += ltt-ring-buffer-metadata-client.o
 obj-m += ltt-relay.o
 ltt-relay-objs :=  ltt-events.o ltt-debugfs-abi.o \
 			ltt-probes.o ltt-core.o ltt-context.o \
-			lttng-context-pid.o
+			lttng-context-pid.o lttng-context-comm.o
 
 obj-m += probes/
 obj-m += lib/
diff --git a/ltt-debugfs-abi.c b/ltt-debugfs-abi.c
index 73082667..afdc09a6 100644
--- a/ltt-debugfs-abi.c
+++ b/ltt-debugfs-abi.c
@@ -154,6 +154,8 @@ long lttng_abi_add_context(struct file *file,
 		return lttng_add_pid_to_ctx(ctx);
 	case LTTNG_KERNEL_CONTEXT_PERF_COUNTER:
 		return -ENOSYS;
+	case LTTNG_KERNEL_CONTEXT_COMM:
+		return lttng_add_comm_to_ctx(ctx);
 	default:
 		return -EINVAL;
 	}
diff --git a/ltt-debugfs-abi.h b/ltt-debugfs-abi.h
index ddc50ba5..2768055f 100644
--- a/ltt-debugfs-abi.h
+++ b/ltt-debugfs-abi.h
@@ -31,9 +31,6 @@ struct lttng_kernel_channel {
 	unsigned int read_timer_interval;	/* usecs */
 };
 
-struct lttng_kernel_tracepoint {
-};
-
 /*
  * Either addr is used, or symbol_name and offset.
  */
@@ -53,7 +50,6 @@ struct lttng_kernel_event {
 	enum lttng_kernel_instrumentation instrumentation;
 	/* Per instrumentation type configuration */
 	union {
-		struct lttng_kernel_tracepoint tracepoint;
 		struct lttng_kernel_kprobe kprobe;
 		struct lttng_kernel_function_tracer ftrace;
 	} u;
@@ -68,9 +64,7 @@ struct lttng_kernel_tracer_version {
 enum lttng_kernel_context_type {
 	LTTNG_KERNEL_CONTEXT_PID,
 	LTTNG_KERNEL_CONTEXT_PERF_COUNTER,
-};
-
-struct lttng_kernel_pid_ctx {
+	LTTNG_KERNEL_CONTEXT_COMM,
 };
 
 struct lttng_kernel_perf_counter_ctx {
@@ -81,7 +75,6 @@ struct lttng_kernel_perf_counter_ctx {
 struct lttng_kernel_context {
 	enum lttng_kernel_context_type ctx;
 	union {
-		struct lttng_kernel_pid_ctx pid;
 		struct lttng_kernel_perf_counter_ctx perf_counter;
 	} u;
 };
diff --git a/ltt-events.h b/ltt-events.h
index a5a57fcd..2b6ef40a 100644
--- a/ltt-events.h
+++ b/ltt-events.h
@@ -273,6 +273,7 @@ void ltt_probes_exit(void);
 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx);
 void lttng_destroy_context(struct lttng_ctx *ctx);
 int lttng_add_pid_to_ctx(struct lttng_ctx **ctx);
+int lttng_add_comm_to_ctx(struct lttng_ctx **ctx);
 
 #ifdef CONFIG_KPROBES
 int lttng_kprobes_register(const char *name,
diff --git a/lttng-context-comm.c b/lttng-context-comm.c
new file mode 100644
index 00000000..6e51bf85
--- /dev/null
+++ b/lttng-context-comm.c
@@ -0,0 +1,69 @@
+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng comm name context.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include "ltt-events.h"
+#include "wrapper/ringbuffer/frontend_types.h"
+#include "wrapper/vmalloc.h"
+#include "ltt-tracer.h"
+
+static
+size_t comm_get_size(size_t offset)
+{
+	size_t size = 0;
+
+	size += sizeof(current->comm);
+	return size;
+}
+
+/*
+ * Racy read of comm. We simply copy its whole array size.
+ * Races with /proc/<task>/comm write only.
+ * Otherwise having to take a mutex for each event is cumbersome and
+ * could lead to crash in IRQ context and deadlock of the lockdep tracer.
+ */
+static
+void comm_record(struct lttng_ctx_field *field,
+		 struct lib_ring_buffer_ctx *ctx,
+		 struct ltt_channel *chan)
+{
+	chan->ops->event_write(ctx, current->comm, sizeof(current->comm));
+}
+
+int lttng_add_comm_to_ctx(struct lttng_ctx **ctx)
+{
+	struct lttng_ctx_field *field;
+	int ret;
+
+	field = lttng_append_context(ctx);
+	if (!field)
+		return ret;
+	field->event_field.name = "comm";
+	field->event_field.type.atype = atype_array;
+	field->event_field.type.u.array.elem_type.atype = atype_integer;
+	field->event_field.type.u.array.elem_type.u.basic.integer.size = sizeof(char) * CHAR_BIT;
+	field->event_field.type.u.array.elem_type.u.basic.integer.alignment = ltt_alignof(char) * CHAR_BIT;
+	field->event_field.type.u.array.elem_type.u.basic.integer.signedness = is_signed_type(char);
+	field->event_field.type.u.array.elem_type.u.basic.integer.reverse_byte_order = 0;
+	field->event_field.type.u.array.elem_type.u.basic.integer.base = 10;
+	field->event_field.type.u.array.elem_type.u.basic.integer.encoding = lttng_encode_UTF8;
+	field->event_field.type.u.array.length = sizeof(current->comm);
+
+	field->get_size = comm_get_size;
+	field->record = comm_record;
+	wrapper_vmalloc_sync_all();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_comm_to_ctx);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Perf Support");