lttng-context-ppid.c

   1 /*
   2  * (C) Copyright        2009-2011 -
   3  *              Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * LTTng PPID 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 <linux/syscalls.h>
  14 #include "lttng-events.h"
  15 #include "wrapper/ringbuffer/frontend_types.h"
  16 #include "wrapper/vmalloc.h"
  17 #include "lttng-tracer.h"
  18
  19 static
  20 size_t ppid_get_size(size_t offset)
  21 {
  22         size_t size = 0;
  23
  24         size += lib_ring_buffer_align(offset, lttng_alignof(pid_t));
  25         size += sizeof(pid_t);
  26         return size;
  27 }
  28
  29 static
  30 void ppid_record(struct lttng_ctx_field *field,
  31                  struct lib_ring_buffer_ctx *ctx,
  32                  struct lttng_channel *chan)
  33 {
  34         pid_t ppid;
  35
  36         rcu_read_lock();
  37         ppid = task_tgid_nr(current->real_parent);
  38         rcu_read_unlock();
  39         lib_ring_buffer_align_ctx(ctx, lttng_alignof(ppid));
  40         chan->ops->event_write(ctx, &ppid, sizeof(ppid));
  41 }
  42
  43 int lttng_add_ppid_to_ctx(struct lttng_ctx **ctx)
  44 {
  45         struct lttng_ctx_field *field;
  46
  47         field = lttng_append_context(ctx);
  48         if (!field)
  49                 return -ENOMEM;
  50         if (lttng_find_context(*ctx, "ppid")) {
  51                 lttng_remove_context_field(ctx, field);
  52                 return -EEXIST;
  53         }
  54         field->event_field.name = "ppid";
  55         field->event_field.type.atype = atype_integer;
  56         field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
  57         field->event_field.type.u.basic.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT;
  58         field->event_field.type.u.basic.integer.signedness = is_signed_type(pid_t);
  59         field->event_field.type.u.basic.integer.reverse_byte_order = 0;
  60         field->event_field.type.u.basic.integer.base = 10;
  61         field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
  62         field->get_size = ppid_get_size;
  63         field->record = ppid_record;
  64         wrapper_vmalloc_sync_all();
  65         return 0;
  66 }
  67 EXPORT_SYMBOL_GPL(lttng_add_ppid_to_ctx);
  68
  69 MODULE_LICENSE("GPL and additional rights");
  70 MODULE_AUTHOR("Mathieu Desnoyers");
  71 MODULE_DESCRIPTION("Linux Trace Toolkit PPID Context");