projects / lttng-modules.git / blame
| Commit | Line | Data |
|---|---|---|
| 25b2f99a MD |
1 | /* |
| 2 | * (C) Copyright 2009-2011 - | |
| 3 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
| 4 | * | |
| 5 | * LTTng comm name context. | |
| 6 | * | |
| 7 | * Dual LGPL v2.1/GPL v2 license. | |
| 8 | */ | |
| 9 | ||
| 10 | #include <linux/module.h> | |
| 11 | #include <linux/slab.h> | |
| 12 | #include <linux/sched.h> | |
| 13 | #include "ltt-events.h" | |
| 14 | #include "wrapper/ringbuffer/frontend_types.h" | |
| 15 | #include "wrapper/vmalloc.h" | |
| 16 | #include "ltt-tracer.h" | |
| 17 | ||
| 18 | static | |
| 19 | size_t comm_get_size(size_t offset) | |
| 20 | { | |
| 21 | size_t size = 0; | |
| 22 | ||
| 23 | size += sizeof(current->comm); | |
| 24 | return size; | |
| 25 | } | |
| 26 | ||
| 27 | /* | |
| 28 | * Racy read of comm. We simply copy its whole array size. | |
| 29 | * Races with /proc/<task>/comm write only. | |
| 30 | * Otherwise having to take a mutex for each event is cumbersome and | |
| 31 | * could lead to crash in IRQ context and deadlock of the lockdep tracer. | |
| 32 | */ | |
| 33 | static | |
| 34 | void comm_record(struct lttng_ctx_field *field, | |
| 35 | struct lib_ring_buffer_ctx *ctx, | |
| 36 | struct ltt_channel *chan) | |
| 37 | { | |
| 38 | chan->ops->event_write(ctx, current->comm, sizeof(current->comm)); | |
| 39 | } | |
| 40 | ||
| 41 | int lttng_add_comm_to_ctx(struct lttng_ctx **ctx) | |
| 42 | { | |
| 43 | struct lttng_ctx_field *field; | |
| 25b2f99a MD |
44 | |
| 45 | field = lttng_append_context(ctx); | |
| 46 | if (!field) | |
| 09fec6b4 | 47 | return -ENOMEM; |
| 44252f0f MD |
48 | if (lttng_find_context(*ctx, "comm")) { |
| 49 | lttng_remove_context_field(ctx, field); | |
| 50 | return -EEXIST; | |
| 51 | } | |
| 25b2f99a MD |
52 | field->event_field.name = "comm"; |
| 53 | field->event_field.type.atype = atype_array; | |
| 54 | field->event_field.type.u.array.elem_type.atype = atype_integer; | |
| 55 | field->event_field.type.u.array.elem_type.u.basic.integer.size = sizeof(char) * CHAR_BIT; | |
| 56 | field->event_field.type.u.array.elem_type.u.basic.integer.alignment = ltt_alignof(char) * CHAR_BIT; | |
| 57 | field->event_field.type.u.array.elem_type.u.basic.integer.signedness = is_signed_type(char); | |
| 58 | field->event_field.type.u.array.elem_type.u.basic.integer.reverse_byte_order = 0; | |
| 59 | field->event_field.type.u.array.elem_type.u.basic.integer.base = 10; | |
| 60 | field->event_field.type.u.array.elem_type.u.basic.integer.encoding = lttng_encode_UTF8; | |
| 61 | field->event_field.type.u.array.length = sizeof(current->comm); | |
| 62 | ||
| 63 | field->get_size = comm_get_size; | |
| 64 | field->record = comm_record; | |
| 65 | wrapper_vmalloc_sync_all(); | |
| 66 | return 0; | |
| 67 | } | |
| 68 | EXPORT_SYMBOL_GPL(lttng_add_comm_to_ctx); | |
| 69 | ||
| 70 | MODULE_LICENSE("GPL and additional rights"); | |
| 71 | MODULE_AUTHOR("Mathieu Desnoyers"); | |
| 72 | MODULE_DESCRIPTION("Linux Trace Toolkit Perf Support"); |