lttng-context-vtid.c

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