lttng-context-vpid.c

   1 /*
   2  * lttng-context-vpid.c
   3  *
   4  * LTTng vPID 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 vpid_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 vpid_record(struct lttng_ctx_field *field,
  43                  struct lib_ring_buffer_ctx *ctx,
  44                  struct lttng_channel *chan)
  45 {
  46         pid_t vpid;
  47
  48         /*
  49          * nsproxy can be NULL when scheduled out of exit.
  50          */
  51         if (!current->nsproxy)
  52                 vpid = 0;
  53         else
  54                 vpid = task_tgid_vnr(current);
  55         lib_ring_buffer_align_ctx(ctx, lttng_alignof(vpid));
  56         chan->ops->event_write(ctx, &vpid, sizeof(vpid));
  57 }
  58
  59 int lttng_add_vpid_to_ctx(struct lttng_ctx **ctx)
  60 {
  61         struct lttng_ctx_field *field;
  62
  63         field = lttng_append_context(ctx);
  64         if (!field)
  65                 return -ENOMEM;
  66         if (lttng_find_context(*ctx, "vpid")) {
  67                 lttng_remove_context_field(ctx, field);
  68                 return -EEXIST;
  69         }
  70         field->event_field.name = "vpid";
  71         field->event_field.type.atype = atype_integer;
  72         field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
  73         field->event_field.type.u.basic.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT;
  74         field->event_field.type.u.basic.integer.signedness = is_signed_type(pid_t);
  75         field->event_field.type.u.basic.integer.reverse_byte_order = 0;
  76         field->event_field.type.u.basic.integer.base = 10;
  77         field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
  78         field->get_size = vpid_get_size;
  79         field->record = vpid_record;
  80         wrapper_vmalloc_sync_all();
  81         return 0;
  82 }
  83 EXPORT_SYMBOL_GPL(lttng_add_vpid_to_ctx);
  84
  85 MODULE_LICENSE("GPL and additional rights");
  86 MODULE_AUTHOR("Mathieu Desnoyers");
  87 MODULE_DESCRIPTION("Linux Trace Toolkit vPID Context");