lttng-context-vtid.c

   1 /*
   2  * lttng-context-vtid.c
   3  *
   4  * LTTng vTID context.
   5  *
   6  * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/slab.h>
  25 #include <linux/sched.h>
  26 #include <lttng-events.h>
  27 #include <wrapper/ringbuffer/frontend_types.h>
  28 #include <wrapper/vmalloc.h>
  29 #include <lttng-tracer.h>
  30
  31 static
  32 size_t vtid_get_size(size_t offset)
  33 {
  34         size_t size = 0;
  35
  36         size += lib_ring_buffer_align(offset, lttng_alignof(pid_t));
  37         size += sizeof(pid_t);
  38         return size;
  39 }
  40
  41 static
  42 void vtid_record(struct lttng_ctx_field *field,
  43                  struct lib_ring_buffer_ctx *ctx,
  44                  struct lttng_channel *chan)
  45 {
  46         pid_t vtid;
  47
  48         /*
  49          * nsproxy can be NULL when scheduled out of exit.
  50          */
  51         if (!current->nsproxy)
  52                 vtid = 0;
  53         else
  54                 vtid = task_pid_vnr(current);
  55         lib_ring_buffer_align_ctx(ctx, lttng_alignof(vtid));
  56         chan->ops->event_write(ctx, &vtid, sizeof(vtid));
  57 }
  58
  59 static
  60 void vtid_get_value(struct lttng_ctx_field *field,
  61                 struct lttng_probe_ctx *lttng_probe_ctx,
  62                 union lttng_ctx_value *value)
  63 {
  64         pid_t vtid;
  65
  66         /*
  67          * nsproxy can be NULL when scheduled out of exit.
  68          */
  69         if (!current->nsproxy)
  70                 vtid = 0;
  71         else
  72                 vtid = task_pid_vnr(current);
  73         value->s64 = vtid;
  74 }
  75
  76 int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx)
  77 {
  78         struct lttng_ctx_field *field;
  79
  80         field = lttng_append_context(ctx);
  81         if (!field)
  82                 return -ENOMEM;
  83         if (lttng_find_context(*ctx, "vtid")) {
  84                 lttng_remove_context_field(ctx, field);
  85                 return -EEXIST;
  86         }
  87         field->event_field.name = "vtid";
  88         field->event_field.type.atype = atype_integer;
  89         field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
  90         field->event_field.type.u.basic.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT;
  91         field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(pid_t);
  92         field->event_field.type.u.basic.integer.reverse_byte_order = 0;
  93         field->event_field.type.u.basic.integer.base = 10;
  94         field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
  95         field->get_size = vtid_get_size;
  96         field->record = vtid_record;
  97         field->get_value = vtid_get_value;
  98         lttng_context_update(*ctx);
  99         wrapper_vmalloc_sync_all();
 100         return 0;
 101 }
 102 EXPORT_SYMBOL_GPL(lttng_add_vtid_to_ctx);