drivers/staging/lttng/lttng-context-pid.c

   1 /*
   2  * (C) Copyright        2009-2011 -
   3  *              Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * LTTng PID 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 pid_get_size(size_t offset)
  20 {
  21         size_t size = 0;
  22
  23         size += lib_ring_buffer_align(offset, ltt_alignof(pid_t));
  24         size += sizeof(pid_t);
  25         return size;
  26 }
  27
  28 static
  29 void pid_record(struct lttng_ctx_field *field,
  30                 struct lib_ring_buffer_ctx *ctx,
  31                 struct ltt_channel *chan)
  32 {
  33         pid_t pid;
  34
  35         pid = task_tgid_nr(current);
  36         lib_ring_buffer_align_ctx(ctx, ltt_alignof(pid));
  37         chan->ops->event_write(ctx, &pid, sizeof(pid));
  38 }
  39
  40 int lttng_add_pid_to_ctx(struct lttng_ctx **ctx)
  41 {
  42         struct lttng_ctx_field *field;
  43
  44         field = lttng_append_context(ctx);
  45         if (!field)
  46                 return -ENOMEM;
  47         if (lttng_find_context(*ctx, "pid")) {
  48                 lttng_remove_context_field(ctx, field);
  49                 return -EEXIST;
  50         }
  51         field->event_field.name = "pid";
  52         field->event_field.type.atype = atype_integer;
  53         field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
  54         field->event_field.type.u.basic.integer.alignment = ltt_alignof(pid_t) * CHAR_BIT;
  55         field->event_field.type.u.basic.integer.signedness = is_signed_type(pid_t);
  56         field->event_field.type.u.basic.integer.reverse_byte_order = 0;
  57         field->event_field.type.u.basic.integer.base = 10;
  58         field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
  59         field->get_size = pid_get_size;
  60         field->record = pid_record;
  61         wrapper_vmalloc_sync_all();
  62         return 0;
  63 }
  64 EXPORT_SYMBOL_GPL(lttng_add_pid_to_ctx);
  65
  66 MODULE_LICENSE("GPL and additional rights");
  67 MODULE_AUTHOR("Mathieu Desnoyers");
  68 MODULE_DESCRIPTION("Linux Trace Toolkit PID Context");